Including read preference options in parse query (#855)

* Including read preference options in parse query

* Turning includeReadPreference and subqueryReadPreference optional when using query.readPreference() method

Author: davimacedo

src/ParseQuery.js

@@ -36,6 +36,9 @@ export type QueryJSON = {
   order?: string;
   className?: string;
   count?: number;
+  readPreference?: string;
+  includeReadPreference?: string;
+  subqueryReadPreference?: string;
 };
 
 /**
@@ -220,6 +223,9 @@ class ParseQuery {
   _limit: number;
   _skip: number;
   _order: Array<string>;
+  _readPreference: string;
+  _includeReadPreference: string;
+  _subqueryReadPreference: string;
   _queriesLocalDatastore: boolean;
   _localDatastorePinName: any;
   _extraOptions: { [key: string]: mixed };
@@ -253,6 +259,9 @@ class ParseQuery {
     this._include = [];
     this._limit = -1; // negative limit is not sent in the server request
     this._skip = 0;
+    this._readPreference = null;
+    this._includeReadPreference = null;
+    this._subqueryReadPreference = null;
     this._queriesLocalDatastore = false;
     this._localDatastorePinName = null;
     this._extraOptions = {};
@@ -391,6 +400,15 @@ class ParseQuery {
     if (this._order) {
       params.order = this._order.join(',');
     }
+    if (this._readPreference) {
+      params.readPreference = this._readPreference;
+    }
+    if (this._includeReadPreference) {
+      params.includeReadPreference = this._includeReadPreference;
+    }
+    if (this._subqueryReadPreference) {
+      params.subqueryReadPreference = this._subqueryReadPreference;
+    }
     for (const key in this._extraOptions) {
       params[key] = this._extraOptions[key];
     }
@@ -444,9 +462,21 @@ class ParseQuery {
       this._order = json.order.split(",");
     }
 
+    if (json.readPreference) {
+      this._readPreference = json.readPreference;
+    }
+
+    if (json.includeReadPreference) {
+      this._includeReadPreference = json.includeReadPreference;
+    }
+
+    if (json.subqueryReadPreference) {
+      this._subqueryReadPreference = json.subqueryReadPreference;
+    }
+
     for (const key in json) {
       if (json.hasOwnProperty(key))  {
-        if (["where", "include", "keys", "limit", "skip", "order"].indexOf(key) === -1) {
+        if (["where", "include", "keys", "limit", "skip", "order", "readPreference", "includeReadPreference", "subqueryReadPreference"].indexOf(key) === -1) {
           this._extraOptions[key] = json[key];
         }
       }
@@ -1482,6 +1512,20 @@ class ParseQuery {
     return this;
   }
 
+  /**
+   * Changes the read preference that the backend will use when performing the query to the database.
+   * @param {String} readPreference The read preference for the main query.
+   * @param {String} includeReadPreference The read preference for the queries to include pointers.
+   * @param {String} subqueryReadPreference The read preference for the sub queries.
+   * @return {Parse.Query} Returns the query, so you can chain this call.
+   */
+  readPreference(readPreference: string, includeReadPreference?: string, subqueryReadPreference?: string): ParseQuery {
+    this._readPreference = readPreference;
+    this._includeReadPreference = includeReadPreference;
+    this._subqueryReadPreference = subqueryReadPreference;
+    return this;
+  }
+
   /**
    * Subscribe this query to get liveQuery updates
    *

src/__tests__/ParseQuery-test.js

@@ -1315,7 +1315,10 @@ describe('ParseQuery', () => {
             size: {
               $in: ['small', 'medium']
             }
-          }
+          },
+          readPreference: 'PRIMARY',
+          includeReadPreference: 'SECONDARY',
+          subqueryReadPreference: 'SECONDARY_PREFERRED',
         });
         expect(options).toEqual({});
         return Promise.resolve({
@@ -1333,6 +1336,7 @@ describe('ParseQuery', () => {
       .skip(8)
       .ascending('createdAt')
       .select('size', 'name')
+      .readPreference('PRIMARY', 'SECONDARY', 'SECONDARY_PREFERRED')
       .find()
       .then((objs) => {
         expect(objs.length).toBe(2);