MOBILE-1633 core: Rating components and providers

scripts/langindex.json

@@ -1590,6 +1590,15 @@
   "core.question.questionno": "question",
   "core.question.requiresgrading": "question",
   "core.quotausage": "moodle",
+  "core.rating.aggregateavg": "moodle",
+  "core.rating.aggregatecount": "moodle",
+  "core.rating.aggregatemax": "moodle",
+  "core.rating.aggregatemin": "moodle",
+  "core.rating.aggregatesum": "moodle",
+  "core.rating.norating": "local_moodlemobileapp",
+  "core.rating.noratings": "moodle",
+  "core.rating.rating": "moodle",
+  "core.rating.ratings": "moodle",
   "core.redirectingtosite": "local_moodlemobileapp",
   "core.refresh": "moodle",
   "core.remove": "moodle",

src/app/app.module.ts

@@ -78,6 +78,7 @@ import { CoreCompileModule } from '@core/compile/compile.module';
 import { CoreQuestionModule } from '@core/question/question.module';
 import { CoreCommentsModule } from '@core/comments/comments.module';
 import { CoreBlockModule } from '@core/block/block.module';
+import { CoreRatingModule } from '@core/rating/rating.module';
 
 // Addon modules.
 import { AddonBadgesModule } from '@addon/badges/badges.module';
@@ -198,6 +199,7 @@ export const CORE_PROVIDERS: any[] = [
         CoreQuestionModule,
         CoreCommentsModule,
         CoreBlockModule,
+        CoreRatingModule,
         AddonBadgesModule,
         AddonBlogModule,
         AddonCalendarModule,

src/assets/lang/en.json

@@ -1590,6 +1590,15 @@
     "core.question.questionno": "Question {{$a}}",
     "core.question.requiresgrading": "Requires grading",
     "core.quotausage": "You have currently used {{$a.used}} of your {{$a.total}} limit.",
+    "core.rating.aggregateavg": "Average of ratings",
+    "core.rating.aggregatecount": "Count of ratings",
+    "core.rating.aggregatemax": "Maximum rating",
+    "core.rating.aggregatemin": "Minimum rating",
+    "core.rating.aggregatesum": "Sum of ratings",
+    "core.rating.norating": "No rating",
+    "core.rating.noratings": "No ratings submitted",
+    "core.rating.rating": "Rating",
+    "core.rating.ratings": "Ratings",
     "core.redirectingtosite": "You will be redirected to the site.",
     "core.refresh": "Refresh",
     "core.remove": "Remove",

src/core/rating/components/aggregate/aggregate.ts

@@ -0,0 +1,112 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { Component, Input, OnChanges, SimpleChange } from '@angular/core';
+import { ModalController } from 'ionic-angular';
+import { CoreEventsProvider } from '@providers/events';
+import { CoreRatingProvider, CoreRatingInfo, CoreRatingInfoItem } from '@core/rating/providers/rating';
+
+/**
+ * Component that displays the aggregation of a rating item.
+ */
+@Component({
+    selector: 'core-rating-aggregate',
+    templateUrl: 'core-rating-aggregate.html'
+})
+export class CoreRatingAggregateComponent implements OnChanges {
+    @Input() ratingInfo: CoreRatingInfo;
+    @Input() contextLevel: string;
+    @Input() instanceId: number;
+    @Input() itemId: number;
+    @Input() aggregateMethod: number;
+    @Input() scaleId: number;
+    @Input() courseId?: number;
+
+    protected labelKey: string;
+    protected showCount: boolean;
+    protected item: CoreRatingInfoItem;
+    protected aggregateObserver;
+
+    constructor(private eventsProvider: CoreEventsProvider, private modalCtrl: ModalController) {}
+
+    /**
+     * Detect changes on input properties.
+     */
+    ngOnChanges(changes: {[name: string]: SimpleChange}): void {
+        this.aggregateObserver && this.aggregateObserver.off();
+
+        this.item = (this.ratingInfo.ratings || []).find((rating) => rating.itemid == this.itemId);
+        if (!this.item) {
+            return;
+        }
+
+        if (this.aggregateMethod == CoreRatingProvider.AGGREGATE_AVERAGE) {
+            this.labelKey = 'core.rating.aggregateavg';
+        } else if (this.aggregateMethod == CoreRatingProvider.AGGREGATE_COUNT) {
+            this.labelKey = 'core.rating.aggregatecount';
+        } else if (this.aggregateMethod == CoreRatingProvider.AGGREGATE_MAXIMUM) {
+            this.labelKey = 'core.rating.aggregatemax';
+        } else if (this.aggregateMethod == CoreRatingProvider.AGGREGATE_MINIMUM) {
+            this.labelKey = 'core.rating.aggregatemin';
+        } else if (this.aggregateMethod == CoreRatingProvider.AGGREGATE_SUM) {
+            this.labelKey = 'core.rating.aggregatesum';
+        } else {
+            this.labelKey = '';
+
+            return;
+        }
+
+        this.showCount = (this.aggregateMethod != CoreRatingProvider.AGGREGATE_COUNT);
+
+        // Update aggrgate when the user adds or edits a rating.
+        this.aggregateObserver = this.eventsProvider.on(CoreRatingProvider.AGGREGATE_CHANGED_EVENT, (data) => {
+            if (data.contextLevel == this.contextLevel &&
+                    data.instanceId == this.instanceId &&
+                    data.component == this.ratingInfo.component &&
+                    data.ratingArea == this.ratingInfo.ratingarea &&
+                    data.itemId == this.itemId) {
+                this.item.aggregatestr = data.aggregate;
+                this.item.count = data.count;
+            }
+        });
+    }
+
+    /**
+     * Open the individual ratings page.
+     */
+    openRatings(): void {
+        if (!this.ratingInfo.canviewall || !this.item.count) {
+            return;
+        }
+
+        const params = {
+            contextLevel: this.contextLevel,
+            instanceId: this.instanceId,
+            ratingComponent: this.ratingInfo.component,
+            ratingArea: this.ratingInfo.ratingarea,
+            itemId: this.itemId,
+            scaleId: this.scaleId,
+            courseId: this.courseId
+        };
+        const modal = this.modalCtrl.create('CoreRatingRatingsPage', params);
+        modal.present();
+    }
+
+    /**
+     * Component being destroyed.
+     */
+    ngOnDestroy(): void {
+        this.aggregateObserver && this.aggregateObserver.off();
+    }
+}

src/core/rating/components/aggregate/core-rating-aggregate.html

@@ -0,0 +1,4 @@
+<a *ngIf="item && item.canviewaggregate && labelKey" ion-item text-wrap [attr.detail-none]="ratingInfo.canviewall && item.count ? null : true" (click)="openRatings()">
+    {{ labelKey | translate }}{{ 'core.labelsep' | translate }} {{ item.aggregatestr || '-' }}
+    <span *ngIf="showCount && item.count > 0">({{ item.count }})</span>
+</a>

src/core/rating/components/components.module.ts

@@ -0,0 +1,39 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { NgModule } from '@angular/core';
+import { CommonModule } from '@angular/common';
+import { IonicModule } from 'ionic-angular';
+import { TranslateModule } from '@ngx-translate/core';
+import { CoreRatingAggregateComponent } from './aggregate/aggregate';
+import { CoreRatingRateComponent } from './rate/rate';
+
+@NgModule({
+    declarations: [
+        CoreRatingAggregateComponent,
+        CoreRatingRateComponent
+    ],
+    imports: [
+        CommonModule,
+        IonicModule,
+        TranslateModule.forChild()
+    ],
+    providers: [
+    ],
+    exports: [
+        CoreRatingAggregateComponent,
+        CoreRatingRateComponent
+    ]
+})
+export class CoreRatingComponentsModule {}

src/core/rating/components/rate/core-rating-rate.html

@@ -0,0 +1,6 @@
+<ion-item text-wrap *ngIf="item && (item.canrate || item.rating != null)">
+    <ion-label>{{ 'core.rating.rating' | translate }}</ion-label>
+    <ion-select text-start [(ngModel)]="rating" (ngModelChange)="userRatingChanged()" interface="action-sheet" [disabled]="!item.canrate">
+        <ion-option *ngFor="let scaleItem of scale.items" [value]="scaleItem.value">{{ scaleItem.name }}</ion-option>
+    </ion-select>
+</ion-item>

src/core/rating/components/rate/rate.ts

@@ -0,0 +1,106 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { Component, Input, OnChanges, SimpleChange } from '@angular/core';
+import { TranslateService } from '@ngx-translate/core';
+import { CoreRatingProvider, CoreRatingInfo, CoreRatingInfoItem, CoreRatingScale } from '@core/rating/providers/rating';
+import { CoreDomUtilsProvider } from '@providers/utils/dom';
+import { CoreRatingOfflineProvider } from '@core/rating/providers/offline';
+
+/**
+ * Component that displays the user rating select.
+ */
+@Component({
+    selector: 'core-rating-rate',
+    templateUrl: 'core-rating-rate.html'
+})
+export class CoreRatingRateComponent implements OnChanges {
+    @Input() ratingInfo: CoreRatingInfo;
+    @Input() contextLevel: string; // Context level: course, module, user, etc.
+    @Input() instanceId: number; // Context instance id.
+    @Input() itemId: number; // Item id. Example: forum post id.
+    @Input() itemSetId: number; // Item set id. Example: forum discussion id.
+    @Input() courseId: number;
+    @Input() aggregateMethod: number;
+    @Input() scaleId: number;
+    @Input() userId: number;
+
+    item: CoreRatingInfoItem;
+    scale: CoreRatingScale;
+    rating: number;
+
+    constructor(private domUtils: CoreDomUtilsProvider, private translate: TranslateService,
+            private ratingProvider: CoreRatingProvider, private ratingOffline: CoreRatingOfflineProvider) {}
+
+    /**
+     * Detect changes on input properties.
+     */
+    ngOnChanges(changes: {[name: string]: SimpleChange}): void {
+        this.item = (this.ratingInfo.ratings || []).find((rating) => rating.itemid == this.itemId);
+        this.scale = (this.ratingInfo.scales || []).find((scale) => scale.id == this.scaleId);
+
+        if (!this.item || !this.scale || !this.ratingProvider.isAddRatingWSAvailable()) {
+            this.item = null;
+
+            return;
+        }
+
+        // Set numeric scale items.
+        if (!this.scale.items) {
+            this.scale.items = [];
+            if (this.scale.isnumeric) {
+                for (let n = 0; n <= this.scale.max; n++) {
+                    this.scale.items.push({name: String(n), value: n});
+                }
+            }
+        }
+
+        // Add "No rating" item to the scale.
+        if (!this.scale.items[0] || this.scale.items[0].value != CoreRatingProvider.UNSET_RATING) {
+            this.scale.items.unshift({
+                name: this.translate.instant('core.rating.norating'),
+                value: CoreRatingProvider.UNSET_RATING
+            });
+        }
+
+        this.ratingOffline.getRating(this.contextLevel, this.instanceId, this.ratingInfo.component, this.ratingInfo.ratingarea,
+                this.itemId).then((rating) => {
+            this.rating = rating.rating;
+        }).catch(() => {
+            if (this.item && this.item.rating != null) {
+                this.rating = this.item.rating;
+            } else {
+                this.rating = CoreRatingProvider.UNSET_RATING;
+            }
+        });
+    }
+
+    /**
+     * Send or save the user rating when changed.
+     */
+    protected userRatingChanged(): void {
+        const modal = this.domUtils.showModalLoading('core.sending', true);
+        this.ratingProvider.addRating(this.ratingInfo.component, this.ratingInfo.ratingarea, this.contextLevel, this.instanceId,
+                this.itemId, this.itemSetId, this.courseId, this.scaleId, this.rating, this.userId, this.aggregateMethod)
+                .then((response) => {
+            if (response == null) {
+                this.domUtils.showToast('core.datastoredoffline', true, 3000);
+            }
+        }).catch((error) => {
+            this.domUtils.showErrorModal(error);
+        }).finally(() => {
+            modal.dismiss();
+        });
+    }
+}

src/core/rating/lang/en.json

@@ -0,0 +1,11 @@
+{
+    "aggregateavg": "Average of ratings",
+    "aggregatecount": "Count of ratings",
+    "aggregatemax": "Maximum rating",
+    "aggregatemin": "Minimum rating",
+    "aggregatesum": "Sum of ratings",
+    "norating": "No rating",
+    "noratings": "No ratings submitted",
+    "rating": "Rating",
+    "ratings": "Ratings"
+}

src/core/rating/pages/ratings/ratings.html

@@ -0,0 +1,28 @@
+<ion-header>
+    <ion-navbar core-back-button>
+        <ion-title>{{ 'core.rating.ratings' | translate }}</ion-title>
+        <ion-buttons end>
+            <button ion-button icon-only (click)="closeModal()" [attr.aria-label]="'core.close' | translate">
+                <ion-icon name="close"></ion-icon>
+            </button>
+        </ion-buttons>
+    </ion-navbar>
+</ion-header>
+<ion-content>
+    <ion-refresher [enabled]="loaded" (ionRefresh)="refreshRatings($event)">
+        <ion-refresher-content pullingText="{{ 'core.pulltorefresh' | translate }}"></ion-refresher-content>
+    </ion-refresher>
+    <core-loading [hideUntil]="loaded">
+        <ion-list *ngIf="ratings.length > 0">
+            <ion-item text-wrap *ngFor="let rating of ratings">
+                <ion-avatar core-user-avatar [user]="rating" [courseId]="courseId" item-start></ion-avatar>
+                <ion-note item-end padding-left *ngIf="rating.timemodified">
+                    {{ rating.timemodified | coreDateDayOrTime }}
+                </ion-note>
+                <h2><core-format-text [text]="rating.userfullname"></core-format-text></h2>
+                <p>{{ rating.rating }}</p>
+            </ion-item>
+        </ion-list>
+        <core-empty-box *ngIf="ratings.length == 0" icon="stats" [message]="'core.rating.noratings' | translate"></core-empty-box>
+    </core-loading>
+</ion-content>

src/core/rating/pages/ratings/ratings.module.ts

@@ -0,0 +1,35 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { NgModule } from '@angular/core';
+import { IonicPageModule } from 'ionic-angular';
+import { TranslateModule } from '@ngx-translate/core';
+import { CoreRatingRatingsPage } from './ratings';
+import { CoreComponentsModule } from '@components/components.module';
+import { CoreDirectivesModule } from '@directives/directives.module';
+import { CorePipesModule } from '@pipes/pipes.module';
+
+@NgModule({
+    declarations: [
+        CoreRatingRatingsPage
+    ],
+    imports: [
+        CoreComponentsModule,
+        CoreDirectivesModule,
+        CorePipesModule,
+        IonicPageModule.forChild(CoreRatingRatingsPage),
+        TranslateModule.forChild()
+    ],
+})
+export class CoreRatingRatingsPageModule {}

src/core/rating/pages/ratings/ratings.ts

@@ -0,0 +1,95 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { Component } from '@angular/core';
+import { IonicPage, NavParams, ViewController } from 'ionic-angular';
+import { CoreDomUtilsProvider } from '@providers/utils/dom';
+import { CoreRatingProvider, CoreRatingItemRating } from '@core/rating/providers/rating';
+
+/**
+ * Page that displays individual ratings
+ */
+@IonicPage({ segment: 'core-rating-ratings' })
+@Component({
+    selector: 'page-core-rating-ratings',
+    templateUrl: 'ratings.html',
+})
+export class CoreRatingRatingsPage {
+    contextLevel: string;
+    instanceId: number;
+    component: string;
+    ratingArea: string;
+    aggregateMethod: number;
+    itemId: number;
+    scaleId: number;
+    courseId: number;
+    loaded = false;
+    ratings: CoreRatingItemRating[] = [];
+
+    constructor(navParams: NavParams, private viewCtrl: ViewController, private domUtils: CoreDomUtilsProvider,
+            private ratingProvider: CoreRatingProvider) {
+        this.contextLevel = navParams.get('contextLevel');
+        this.instanceId = navParams.get('instanceId');
+        this.component = navParams.get('ratingComponent');
+        this.ratingArea = navParams.get('ratingArea');
+        this.aggregateMethod = navParams.get('aggregateMethod');
+        this.itemId = navParams.get('itemId');
+        this.scaleId = navParams.get('scaleId');
+        this.courseId = navParams.get('courseId');
+    }
+
+    /**
+     * View loaded.
+     */
+    ionViewDidLoad(): void {
+        this.fetchData().finally(() => {
+            this.loaded = true;
+        });
+    }
+
+    /**
+     * Fetch all the data required for the view.
+     *
+     * @return {Promise<any>} Resolved when done.
+     */
+    fetchData(): Promise<any> {
+        return this.ratingProvider.getItemRatings(this.contextLevel, this.instanceId, this.component, this.ratingArea, this.itemId,
+                this.scaleId, undefined, this.courseId).then((ratings) => {
+            this.ratings = ratings;
+        }).catch((error) => {
+            this.domUtils.showErrorModal(error);
+        });
+    }
+
+    /**
+     * Refresh data.
+     *
+     * @param {any} refresher Refresher.
+     */
+    refreshRatings(refresher: any): void {
+        this.ratingProvider.invalidateRatingItems(this.contextLevel, this.instanceId, this.component, this.ratingArea, this.itemId,
+                this.scaleId).finally(() => {
+            return this.fetchData().finally(() => {
+                refresher.complete();
+            });
+        });
+    }
+
+    /**
+     * Close modal.
+     */
+    closeModal(): void {
+        this.viewCtrl.dismiss();
+    }
+}

src/core/rating/providers/offline.ts

@@ -0,0 +1,305 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { Injectable } from '@angular/core';
+import { CoreSitesProvider, CoreSiteSchema } from '@providers/sites';
+import { CoreUtilsProvider } from '@providers/utils/utils';
+
+/**
+ * Structure of offline ratings.
+ */
+export interface CoreRatingOfflineRating {
+    component: string;
+    ratingarea: string;
+    contextlevel: string;
+    instanceid: number;
+    itemid: number;
+    itemsetid: number;
+    courseid: number;
+    scaleid: number;
+    rating: number;
+    rateduserid: number;
+    aggregation: number;
+}
+
+/**
+ * Structure of item sets.
+ */
+export interface CoreRatingItemSet {
+    component: string;
+    ratingArea: string;
+    contextLevel: string;
+    instanceId: number;
+    itemSetId: number;
+    courseId: number;
+}
+
+/**
+ * Service to handle offline data for rating.
+ */
+@Injectable()
+export class CoreRatingOfflineProvider {
+
+    // Variables for database.
+    static RATINGS_TABLE = 'rating_ratings';
+    protected siteSchema: CoreSiteSchema = {
+        name: 'CoreCourseOfflineProvider',
+        version: 1,
+        tables: [
+            {
+                name: CoreRatingOfflineProvider.RATINGS_TABLE,
+                columns: [
+                    {
+                        name: 'component',
+                        type: 'TEXT'
+                    },
+                    {
+                        name: 'ratingarea',
+                        type: 'TEXT'
+                    },
+                    {
+                        name: 'contextlevel',
+                        type: 'INTEGER',
+                    },
+                    {
+                        name: 'instanceid',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'itemid',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'itemsetid',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'courseid',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'scaleid',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'rating',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'rateduserid',
+                        type: 'INTEGER'
+                    },
+                    {
+                        name: 'aggregation',
+                        type: 'INTEGER'
+                    }
+                ],
+                primaryKeys: ['component', 'ratingarea', 'contextlevel', 'instanceid', 'itemid']
+            }
+        ]
+    };
+
+    constructor(private sitesProvider: CoreSitesProvider, private utils: CoreUtilsProvider) {
+        this.sitesProvider.registerSiteSchema(this.siteSchema);
+    }
+
+    /**
+     * Get an offline rating.
+     *
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {numnber} instanceId Context instance id.
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<CoreRatingOfflineRating>} Promise resolved with the saved rating, rejected if not found.
+     */
+    getRating(contextLevel: string, instanceId: number, component: string, ratingArea: string, itemId: number,  siteId?: string):
+            Promise<CoreRatingOfflineRating> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const conditions = {
+                contextlevel: contextLevel,
+                instanceid: instanceId,
+                component: component,
+                ratingarea: ratingArea,
+                itemid: itemId
+            };
+
+            return site.getDb().getRecord(CoreRatingOfflineProvider.RATINGS_TABLE, conditions);
+        });
+    }
+
+    /**
+     * Add an offline rating.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {numnber} instanceId Context instance id.
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} itemSetId Item set id. Example: forum discussion id.
+     * @param {number} courseId Course id.
+     * @param {number} scaleId Scale id.
+     * @param {number} rating Rating value. Use CoreRatingProvider.UNSET_RATING to delete rating.
+     * @param {number} ratedUserId Rated user id.
+     * @param {number} aggregateMethod Aggregate method.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<any>} Promise resolved when the rating is saved.
+     */
+    addRating(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemId: number, itemSetId: number,
+            courseId: number, scaleId: number, rating: number, ratedUserId: number, aggregateMethod: number, siteId?: string):
+            Promise<any> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const data: CoreRatingOfflineRating = {
+                component: component,
+                ratingarea: ratingArea,
+                contextlevel: contextLevel,
+                instanceid: instanceId,
+                itemid: itemId,
+                itemsetid: itemSetId,
+                courseid: courseId,
+                scaleid: scaleId,
+                rating: rating,
+                rateduserid: ratedUserId,
+                aggregation: aggregateMethod
+            };
+
+            return site.getDb().insertRecord(CoreRatingOfflineProvider.RATINGS_TABLE, data);
+        });
+    }
+
+    /**
+     * Delete offline rating.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<any>} Promise resolved when the rating is saved.
+     */
+    deleteRating(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemId: number, siteId?: string):
+            Promise<any> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const conditions = {
+                component: component,
+                ratingarea: ratingArea,
+                contextlevel: contextLevel,
+                instanceid: instanceId,
+                itemid: itemId
+            };
+
+            return site.getDb().deleteRecords(CoreRatingOfflineProvider.RATINGS_TABLE, conditions);
+        });
+    }
+
+    /**
+     * Get the list of item sets in a component or instance.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} [contextLevel] Context level: course, module, user, etc.
+     * @param {numnber} [instanceId] Context instance id.
+     * @param {number} [itemSetId] Item set id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<CoreRatingItemSet[]>} Promise resolved with the list of item set ids.
+     */
+    getItemSets(component: string, ratingArea: string, contextLevel?: string, instanceId?: number, itemSetId?: number,
+            siteId?: string): Promise<CoreRatingItemSet[]> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const fields = 'DISTINCT contextlevel, instanceid, itemsetid, courseid';
+            const conditions: any = {
+                component,
+                ratingarea: ratingArea
+            };
+            if (contextLevel != null && instanceId != null) {
+                conditions.contextlevel = contextLevel;
+                conditions.instanceId = instanceId;
+            }
+            if (itemSetId != null) {
+                conditions.itemSetId = itemSetId;
+            }
+
+            return site.getDb().getRecords(CoreRatingOfflineProvider.RATINGS_TABLE, conditions, undefined, fields)
+                    .then((records: any[]) => {
+                return records.map((record) => {
+                    return {
+                        component,
+                        ratingArea,
+                        contextLevel: record.contextlevel,
+                        instanceId: record.instanceid,
+                        itemSetId: record.itemsetid,
+                        courseId: record.courseid
+                    };
+                });
+            });
+        });
+    }
+
+    /**
+     * Get offline ratings of an item set.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} itemSetId Item set id. Example: forum discussion id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<CoreRatingOfflineRating[]>} Promise resolved with the list of ratings.
+     */
+    getRatings(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemSetId: number, siteId?: string):
+            Promise<CoreRatingOfflineRating[]> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const conditions = {
+                component,
+                ratingarea: ratingArea,
+                contextlevel: contextLevel,
+                instanceid: instanceId,
+                itemsetid: itemSetId
+            };
+
+            return site.getDb().getRecords(CoreRatingOfflineProvider.RATINGS_TABLE, conditions);
+        });
+    }
+
+    /**
+     * Return whether a component, instance or item set has offline ratings.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} [contextLevel] Context level: course, module, user, etc.
+     * @param {number} [instanceId] Context instance id.
+     * @param {number} [itemSetId] Item set id. Example: forum discussion id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<boolean>} Promise resolved with a boolean.
+     */
+    hasRatings(component: string, ratingArea: string, contextLevel?: string, instanceId?: number, itemSetId?: number,
+            siteId?: string): Promise<boolean> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const conditions: any = {
+                component,
+                ratingarea: ratingArea
+            };
+            if (contextLevel != null && instanceId != null) {
+                conditions.contextlevel = contextLevel;
+                conditions.instanceId = instanceId;
+            }
+            if (itemSetId != null) {
+                conditions.itemsetid = itemSetId;
+            }
+
+            return this.utils.promiseWorks(site.getDb().recordExists(CoreRatingOfflineProvider.RATINGS_TABLE, conditions));
+        });
+    }
+}

src/core/rating/providers/rating.ts

@@ -0,0 +1,352 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { Injectable } from '@angular/core';
+import { CoreSiteWSPreSets } from '@classes/site';
+import { CoreAppProvider } from '@providers/app';
+import { CoreEventsProvider } from '@providers/events';
+import { CoreSitesProvider } from '@providers/sites';
+import { CoreUserProvider } from '@core/user/providers/user';
+import { CoreUtilsProvider } from '@providers/utils/utils';
+import { CoreRatingOfflineProvider } from './offline';
+
+/**
+ * Structure of the rating info returned by web services.
+ */
+export interface CoreRatingInfo {
+    contextid: number;
+    component: string;
+    ratingarea: string;
+    canviewall: boolean;
+    canviewany: boolean;
+    scales?: CoreRatingScale[];
+    ratings?: CoreRatingInfoItem[];
+}
+
+/**
+ * Structure of scales in the rating info.
+ */
+export interface CoreRatingScale {
+    id: number;
+    courseid?: number;
+    name?: string;
+    max: number;
+    isnumeric: boolean;
+    items?: {value: number, name: string}[];
+}
+
+/**
+ * Structure of items in the rating info.
+ */
+export interface CoreRatingInfoItem {
+    itemid: number;
+    scaleid?: number;
+    scale?: CoreRatingScale;
+    userid?: number;
+    aggregate?: number;
+    aggregatestr?: string;
+    count?: number;
+    rating?: number;
+    canrate?: boolean;
+    canviewaggregate?: boolean;
+}
+
+/**
+ * Structure of a rating returned by the item ratings web service.
+ */
+export interface CoreRatingItemRating {
+    id: number;
+    userid: number;
+    userpictureurl: string;
+    userfullname: string;
+    rating: string;
+    timemodified: number;
+}
+
+/**
+ * Service to handle ratings.
+ */
+@Injectable()
+export class CoreRatingProvider {
+
+    static AGGREGATE_NONE = 0; // No ratings.
+    static AGGREGATE_AVERAGE = 1;
+    static AGGREGATE_COUNT = 2;
+    static AGGREGATE_MAXIMUM = 3;
+    static AGGREGATE_MINIMUM = 4;
+    static AGGREGATE_SUM = 5;
+
+    static UNSET_RATING = -999;
+
+    static AGGREGATE_CHANGED_EVENT = 'core_rating_aggregate_changed';
+    static RATING_SAVED_EVENT = 'core_rating_rating_saved';
+
+    protected ROOT_CACHE_KEY = 'CoreRating:';
+
+    constructor(private appProvider: CoreAppProvider,
+            private eventsProvider: CoreEventsProvider,
+            private sitesProvider: CoreSitesProvider,
+            private userProvider: CoreUserProvider,
+            private utils: CoreUtilsProvider,
+            private ratingOffline: CoreRatingOfflineProvider) {}
+
+    /**
+     * Returns whether the web serivce to add ratings is available.
+     *
+     * @return {boolean} If WS is abalaible.
+     * @since 3.2
+     */
+    isAddRatingWSAvailable(): boolean {
+        return this.sitesProvider.wsAvailableInCurrentSite('core_rating_add_rating');
+    }
+
+    /**
+     * Add a rating to an item.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} itemSetId Item set id. Example: forum discussion id.
+     * @param {number} courseId Course id.
+     * @param {number} scaleId Scale id.
+     * @param {number} rating Rating value. Use CoreRatingProvider.UNSET_RATING to delete rating.
+     * @param {number} ratedUserId Rated user id.
+     * @param {number} aggregateMethod Aggregate method.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<CoreRatingItemRating|null>} Promise resolved with the aggregated rating or null if stored offline.
+     * @since 3.2
+     */
+    addRating(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemId: number, itemSetId: number,
+            courseId: number, scaleId: number, rating: number, ratedUserId: number, aggregateMethod: number, siteId?: string):
+            Promise<CoreRatingItemRating[]> {
+        siteId = siteId || this.sitesProvider.getCurrentSiteId();
+
+        // Convenience function to store a rating to be synchronized later.
+        const storeOffline = (): Promise<any> => {
+            return this.ratingOffline.addRating(component, ratingArea, contextLevel, instanceId, itemId, itemSetId, courseId,
+                    scaleId, rating, ratedUserId, aggregateMethod, siteId).then(() => {
+                this.eventsProvider.trigger(CoreRatingProvider.RATING_SAVED_EVENT, {
+                    component,
+                    ratingArea,
+                    contextLevel,
+                    instanceId,
+                    itemSetId,
+                    itemId
+                }, siteId);
+
+                return null;
+            });
+        };
+
+        if (!this.appProvider.isOnline()) {
+            // App is offline, store the action.
+            return storeOffline();
+        }
+
+        return this.ratingOffline.deleteRating(component, ratingArea, contextLevel, instanceId, itemId, siteId).then(() => {
+            return this.addRatingOnline(component, ratingArea, contextLevel, instanceId, itemId, scaleId, rating, ratedUserId,
+                    aggregateMethod, siteId).catch((error) => {
+
+                if (this.utils.isWebServiceError(error)) {
+                    // The WebService has thrown an error or offline not supported, reject.
+                    return Promise.reject(error);
+                }
+
+                // Couldn't connect to server, store offline.
+                return storeOffline();
+            });
+        });
+    }
+
+    /**
+     * Add a rating to an item. It will fail if offline or cannot connect.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} scaleId Scale id.
+     * @param {number} rating Rating value. Use CoreRatingProvider.UNSET_RATING to delete rating.
+     * @param {number} ratedUserId Rated user id.
+     * @param {number} aggregateMethod Aggregate method.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<CoreRatingItemRating>} Promise resolved with the aggregated rating.
+     * @since 3.2
+     */
+    addRatingOnline(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemId: number,
+            scaleId: number, rating: number, ratedUserId: number, aggregateMethod: number, siteId?: string):
+            Promise<CoreRatingItemRating> {
+
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const params = {
+                contextlevel: contextLevel,
+                instanceid: instanceId,
+                component: component,
+                ratingarea: ratingArea,
+                itemid: itemId,
+                scaleid: scaleId,
+                rating: rating,
+                rateduserid: ratedUserId,
+                aggregation: aggregateMethod
+            };
+
+            return site.write('core_rating_add_rating', params).then((response) => {
+                return this.invalidateRatingItems(contextLevel, instanceId, component, ratingArea, itemId, scaleId).then(() => {
+                    this.eventsProvider.trigger(CoreRatingProvider.AGGREGATE_CHANGED_EVENT, {
+                        contextLevel,
+                        instanceId,
+                        component,
+                        ratingArea,
+                        itemId,
+                        aggregate: response.aggregate,
+                        count: response.count
+                    });
+
+                    return response;
+                });
+            });
+        });
+    }
+
+    /**
+     * Get item ratings.
+     *
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} scaleId Scale id.
+     * @param {string} [sort="timemodified"] Sort field.
+     * @param {number} [courseId] Course id. Used for fetching user profiles.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @param {boolean} [ignoreCache=false] True if it should ignore cached data (it will always fail in offline or server down).
+     * @return {Promise<CoreRatingItemRating[]>} Promise resolved with the list of ratings.
+     */
+    getItemRatings(contextLevel: string, instanceId: number, component: string, ratingArea: string, itemId: number,
+            scaleId: number, sort: string = 'timemodified', courseId?: number, siteId?: string, ignoreCache: boolean = false):
+            Promise<CoreRatingItemRating[]> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const params = {
+                contextlevel: contextLevel,
+                instanceid: instanceId,
+                component: component,
+                ratingarea: ratingArea,
+                itemid: itemId,
+                scaleid: scaleId,
+                sort: sort
+            };
+            const preSets: CoreSiteWSPreSets = {
+                cacheKey: this.getItemRatingsCacheKey(contextLevel, instanceId, component, ratingArea, itemId, scaleId, sort)
+            };
+            if (ignoreCache) {
+                preSets.getFromCache = false;
+                preSets.emergencyCache = false;
+            }
+
+            return site.read('core_rating_get_item_ratings', params, preSets).then((response) => {
+                if (!response || !response.ratings) {
+                    return Promise.reject(null);
+                }
+
+                // We need to fetch profiles because the returned profile pictures are incorrect.
+                const promises = response.ratings.map((rating: CoreRatingItemRating) => {
+                    return this.userProvider.getProfile(rating.userid, courseId, true, site.id).then((user) => {
+                        rating.userpictureurl = user.profileimageurl;
+                    }).catch(() => {
+                        // Ignore error.
+                        rating.userpictureurl = null;
+                    });
+                });
+
+                return Promise.all(promises).then(() => {
+                    return response.ratings;
+                });
+            });
+        });
+    }
+
+    /**
+     * Invalidate item ratings.
+     *
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} scaleId Scale id.
+     * @param {string} [sort="timemodified"] Sort field.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<any>} Promise resolved when the data is invalidated.
+     */
+    invalidateRatingItems(contextLevel: string, instanceId: number, component: string, ratingArea: string,
+            itemId: number, scaleId: number, sort: string = 'timemodified', siteId?: string): Promise<any> {
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const key = this.getItemRatingsCacheKey(contextLevel, instanceId, component, ratingArea, itemId, scaleId, sort);
+
+            return site.invalidateWsCacheForKey(key);
+        });
+    }
+
+    /**
+     * Prefetch individual ratings.
+     *
+     * This function should be called from the prefetch handler of activities with ratings.
+     *
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Instance id.
+     * @param {string} [siteId] Site id. If not defined, current site.
+     * @param {number} [courseId] Course id. Used for prefetching user profiles.
+     * @param {CoreRatingInfo} [ratingInfo] Rating info returned by web services.
+     * @return {Promise<any>} Promise resolved when done.
+     */
+    prefetchRatings(contextLevel: string, instanceId: number, scaleId: number, courseId?: number, ratingInfo?: CoreRatingInfo,
+            siteId?: string): Promise<any> {
+        if (!ratingInfo || !ratingInfo.ratings) {
+            return Promise.resolve();
+        }
+
+        return this.sitesProvider.getSite(siteId).then((site) => {
+            const promises = ratingInfo.ratings.map((item) => {
+                return this.getItemRatings(contextLevel, instanceId, ratingInfo.component, ratingInfo.ratingarea, item.itemid,
+                        scaleId, undefined, courseId, site.id, true).then((ratings) => {
+                    const userIds = ratings.map((rating: CoreRatingItemRating) => rating.userid);
+
+                    return this.userProvider.prefetchProfiles(userIds, courseId, site.id);
+                });
+            });
+
+            return Promise.all(promises);
+        });
+    }
+
+    /**
+     * Get cache key for rating items WS calls.
+     *
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating area. Example: "post".
+     * @param {number} itemId Item id. Example: forum post id.
+     * @param {number} scaleId Scale id.
+     * @param {string} sort Sort field.
+     * @return {string} Cache key.
+     */
+    protected getItemRatingsCacheKey(contextLevel: string, instanceId: number, component: string, ratingArea: string,
+            itemId: number, scaleId: number, sort: string): string {
+        return `${this.ROOT_CACHE_KEY}${contextLevel}:${instanceId}:${component}:${ratingArea}:${itemId}:${scaleId}:${sort}`;
+    }
+}

src/core/rating/providers/sync.ts

@@ -0,0 +1,196 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { Injectable } from '@angular/core';
+import { TranslateService } from '@ngx-translate/core';
+import { CoreSyncBaseProvider } from '@classes/base-sync';
+import { CoreAppProvider } from '@providers/app';
+import { CoreLoggerProvider } from '@providers/logger';
+import { CoreSitesProvider } from '@providers/sites';
+import { CoreSyncProvider } from '@providers/sync';
+import { CoreTextUtilsProvider } from '@providers/utils/text';
+import { CoreTimeUtilsProvider } from '@providers/utils/time';
+import { CoreUtilsProvider } from '@providers/utils/utils';
+import { CoreRatingProvider } from './rating';
+import { CoreRatingOfflineProvider, CoreRatingItemSet } from './offline';
+import { CoreEventsProvider } from '@providers/events';
+
+/**
+ * Service to sync ratings.
+ */
+@Injectable()
+export class CoreRatingSyncProvider extends CoreSyncBaseProvider {
+
+    static SYNCED_EVENT = 'core_rating_synced';
+
+    constructor(translate: TranslateService,
+            appProvider: CoreAppProvider,
+            private eventsProvider: CoreEventsProvider,
+            loggerProvider: CoreLoggerProvider,
+            sitesProvider: CoreSitesProvider,
+            syncProvider: CoreSyncProvider,
+            textUtils: CoreTextUtilsProvider,
+            timeUtils: CoreTimeUtilsProvider,
+            private utils: CoreUtilsProvider,
+            private ratingProvider: CoreRatingProvider,
+            private ratingOffline: CoreRatingOfflineProvider) {
+
+        super('CoreRatingSyncProvider', loggerProvider, sitesProvider, appProvider, syncProvider, textUtils, translate, timeUtils);
+    }
+
+    /**
+     * Try to synchronize all the ratings of a certain component, instance or item set.
+     *
+     * This function should be called from the sync provider of activities with ratings.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} [contextLevel] Context level: course, module, user, etc.
+     * @param {numnber} [instanceId] Context instance id.
+     * @param {number} [itemSetId] Item set id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<any>} Promise resolved if sync is successful, rejected if sync fails.
+     */
+    syncRatings(component: string, ratingArea: string, contextLevel?: string, instanceId?: number, itemSetId?: number,
+            siteId?: string): Promise<{itemSet: CoreRatingItemSet, updated: boolean, warnings: string[]}[]> {
+        siteId = siteId || this.sitesProvider.getCurrentSiteId();
+
+        return this.ratingOffline.getItemSets(component, ratingArea, contextLevel, instanceId, itemSetId, siteId)
+                .then((itemSets) => {
+            const results = [];
+            const promises = itemSets.map((itemSet) => {
+                return this.syncItemSetIfNeeded(component, ratingArea, itemSet.contextLevel, itemSet.instanceId,
+                        itemSet.itemSetId, siteId).then((result) => {
+                    if (result.updated) {
+                        // Sync successful, send event.
+                        this.eventsProvider.trigger(CoreRatingSyncProvider.SYNCED_EVENT, {
+                            ...itemSet,
+                            warnings: result.warnings
+                        }, siteId);
+                    }
+
+                    results.push({itemSet, ...result});
+                });
+            });
+
+            return Promise.all(promises).then(() => {
+                return results;
+            });
+        });
+    }
+
+    /**
+     * Sync ratings of an item set only if a certain time has passed since the last time.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {number} itemSetId Item set id. Example: forum discussion id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<any>} Promise resolved when ratings are synced or if it doesn't need to be synced.
+     */
+    protected syncItemSetIfNeeded(component: string, ratingArea: string,  contextLevel: string, instanceId: number,
+            itemSetId: number, siteId?: string): Promise<{updated: boolean, warnings: string[]}> {
+        siteId = siteId || this.sitesProvider.getCurrentSiteId();
+
+        const syncId = this.getItemSetSyncId(component, ratingArea, contextLevel, instanceId, itemSetId);
+
+        return this.isSyncNeeded(syncId, siteId).then((needed) => {
+            if (needed) {
+                return this.syncItemSet(component, ratingArea, contextLevel, instanceId, itemSetId, siteId);
+            }
+        });
+    }
+
+    /**
+     * Synchronize all offline ratings of an item set.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {number} itemSetId Item set id. Example: forum discussion id.
+     * @param {string} [siteId] Site ID. If not defined, current site.
+     * @return {Promise<any>} Promise resolved if sync is successful, rejected otherwise.
+     */
+    protected syncItemSet(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemSetId: number,
+            siteId?: string): Promise<{updated: boolean, warnings: string[]}> {
+
+        siteId = siteId || this.sitesProvider.getCurrentSiteId();
+
+        const syncId = this.getItemSetSyncId(component, ratingArea, contextLevel, instanceId, itemSetId);
+        if (this.isSyncing(syncId, siteId)) {
+            // There's already a sync ongoing for this item set, return the promise.
+            return this.getOngoingSync(syncId, siteId);
+        }
+
+        this.logger.debug(`Try to sync ratings of component '${component}' rating area '${ratingArea}'` +
+            ` context level '${contextLevel}' instance ${instanceId} item set ${itemSetId}`);
+
+        let updated = false;
+        const warnings = [];
+
+        return this.ratingOffline.getRatings(component, ratingArea, contextLevel, instanceId, itemSetId, siteId).then((ratings) => {
+            if (!ratings.length) {
+                // Nothing to sync.
+                return;
+            } else if (!this.appProvider.isOnline()) {
+                // Cannot sync in offline.
+                return Promise.reject(null);
+            }
+
+            const promises = ratings.map((rating) => {
+                return this.ratingProvider.addRatingOnline(component, ratingArea, rating.contextlevel, rating.instanceid,
+                        rating.itemid, rating.scaleid, rating.rating, rating.rateduserid, rating.aggregation, siteId)
+                        .catch((error) => {
+                    if (this.utils.isWebServiceError(error)) {
+                        warnings.push(this.textUtils.getErrorMessageFromError(error));
+                    } else {
+                        // Couldn't connect to server, reject.
+                        return Promise.reject(error);
+                    }
+                }).then(() => {
+                    updated = true;
+
+                    return this.ratingOffline.deleteRating(component, ratingArea, rating.contextlevel, rating.instanceid,
+                            rating.itemid, siteId).finally(() => {
+                        return this.ratingProvider.invalidateRatingItems(rating.contextlevel, rating.instanceid, component,
+                                ratingArea, rating.itemid, rating.scaleid, undefined, siteId);
+                    });
+                });
+            });
+
+            return Promise.all(promises).then(() => {
+                // All done, return the warnings.
+                return { updated, warnings };
+            });
+        });
+    }
+
+    /**
+     * Get the sync id of an item set.
+     *
+     * @param {string} component Component. Example: "mod_forum".
+     * @param {string} ratingArea Rating Area. Example: "post".
+     * @param {string} contextLevel Context level: course, module, user, etc.
+     * @param {number} instanceId Context instance id.
+     * @param {number} itemSetId Item set id. Example: forum discussion id.
+     * @return {string} Sync id.
+     */
+    protected getItemSetSyncId(component: string, ratingArea: string, contextLevel: string, instanceId: number, itemSetId: number):
+            string {
+        return `itemSet#${component}#${ratingArea}#${contextLevel}#${instanceId}#${itemSetId}`;
+    }
+}

src/core/rating/rating.module.ts

@@ -0,0 +1,31 @@
+// (C) Copyright 2015 Martin Dougiamas
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { NgModule } from '@angular/core';
+import { CoreRatingProvider } from './providers/rating';
+import { CoreRatingOfflineProvider } from './providers/offline';
+import { CoreRatingSyncProvider } from './providers/sync';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        CoreRatingProvider,
+        CoreRatingOfflineProvider,
+        CoreRatingSyncProvider
+    ]
+})
+export class CoreRatingModule {}