Parse.Query.fromJSON method (#448)

* Parse.Query.fromJSON method

* Parse.Query.fromJSON to static,
Parse.Query.withJSON method

Author: kyptov

src/ParseQuery.js

@@ -261,6 +261,75 @@ export default class ParseQuery {
     return params;
   }
 
+  /**
+   * Return a query with conditions from json, can be useful to send query from server side to client
+   * Not static, all query conditions was set before calling this method will be deleted.
+   * For example on the server side we have
+   * var query = new Parse.Query("className");
+   * query.equalTo(key: value);
+   * query.limit(100);
+   * ... (others queries)
+   * Create JSON representation of Query Object
+   * var jsonFromServer = query.fromJSON();
+   *
+   * On client side getting query:
+   * var query = new Parse.Query("className");
+   * query.fromJSON(jsonFromServer);
+   *
+   * and continue to query...
+   * query.skip(100).find().then(...);
+   * @method withJSON
+   * @param {QueryJSON} json from Parse.Query.toJSON() method
+   * @return {Parse.Query} Returns the query, so you can chain this call.
+   */
+  withJSON(json: QueryJSON): ParseQuery {
+
+    if (json.where) {
+      this._where = json.where;
+    }
+
+    if (json.include) {
+      this._include = json.include.split(",");
+    }
+
+    if (json.keys) {
+      this._select = json.keys.split(",");
+    }
+
+    if (json.limit) {
+      this._limit  = json.limit;
+    }
+
+    if (json.skip) {
+      this._skip = json.skip;
+    }
+
+    if (json.order) {
+      this._order = json.order.split(",");
+    }
+
+    for (let key in json) if (json.hasOwnProperty(key))  {
+      if (["where", "include", "keys", "limit", "skip", "order"].indexOf(key) === -1) {
+        this._extraOptions[key] = json[key];
+      }
+    }
+
+    return this;
+
+  }
+
+    /**
+     * Static method to restore Parse.Query by json representation
+     * Internally calling Parse.Query.withJSON
+     * @param {String} className
+     * @param {QueryJSON} json from Parse.Query.toJSON() method
+     * @returns {Parse.Query} new created query
+     */
+  static fromJSON(className: string, json: QueryJSON): ParseQuery {
+    const query = new ParseQuery(className);
+    return query.withJSON(json);
+  }
+
   /**
    * Constructs a Parse.Object whose id is already known by fetching data from
    * the server.  Either options.success or options.error is called when the

src/__tests__/ParseQuery-test.js

@@ -1555,4 +1555,33 @@ describe('ParseQuery', () => {
       done.fail(error);
     });
   });
+
+  it('restores queries from json representation', () => {
+    const q = new ParseQuery('Item');
+
+    q.include('manufacturer');
+    q.select('inStock', 'lastPurchase');
+    q.limit(10);
+    q.ascending(['a', 'b', 'c']);
+    q.skip(4);
+    q.equalTo('size', 'medium');
+
+    const json = q.toJSON();
+
+    const newQuery = ParseQuery.fromJSON('Item', json);
+
+    expect(newQuery.className).toBe('Item');
+
+    expect(newQuery.toJSON()).toEqual({
+      include: 'manufacturer',
+      keys: 'inStock,lastPurchase',
+      limit: 10,
+      order: 'a,b,c',
+      skip: 4,
+      where: {
+        size: 'medium'
+      }
+    });
+
+  });
 });