An example of using inner queries to filter data in Parse

parse-inner-queries.js

Parse.initialize("honfjbWg6gddGuKOHokS5XaJCFMIW66nOV22138i", "EyOqRoG2xLM6UYHTV5LhehQgDuwjogYp86Il1umM");

	var ProjectModel = Parse.Object.extend('Project');
	var TaskModel = Parse.Object.extend('Task');
	var UserModel = Parse.User;

	// All tasks for a specific project
	var projectId = 'xVwXfflkib';
	var targetProjectModel = new ProjectModel({objectId: projectId, name: 'Nutella'});
	var query = new Parse.Query(TaskModel); // Pass in model of things you want to get back
	query.equalTo('projectId', targetProjectModel);
	query.find().then(function(results) {
		console.log(results);
	});

	// All tasks for a specific user
	var userId = 'qXRvjks2O6';
	var targetUserModel = new UserModel({objectId: userId});
	var query = new Parse.Query(TaskModel); // Pass in model of things you want to get back
	var innerQuery = new Parse.Query(ProjectModel);
	innerQuery.equalTo('userId', targetUserModel);
	query.matchesQuery('projectId', innerQuery);
	query.include('projectId');
	query.find().then(function(results) {	// results coming back will be an array of tasks

		// Group the results by their project id
		// groupedResults will be an object with one property for each unique projectId.
		// Each property will store an array of tasks
		var groupedResults = _.groupBy(results, function(task) {	
			return task.get('projectId').id;
		});

		// Display the grouped results by iterating over each property in the object.
		// i will be a string storing the name of the property in the object (in this case the projectId)
		for(var i in groupedResults) {
			console.log(i);
			// groupedResults[i] will be an array of tasks
			for(var j = 0; j<groupedResults[i].length; j++) {
				// display each task in the array of tasks
				console.log(' - '+ groupedResults[i][j].get('description'));
			}
		}

	});