Ionic and $cordovaSQLite - how to ensure factory ready?


#1

Hi, first post, cross-posting this from Stack Overflow as it might be better known here. I’ve read Factory wrapper for SQLite plugin but still not certain on how to proceed. Thanks! *

I’m writing a PhoneGap/Cordova app with Ionic, and using SQLite (with ngCordova) for persistent storage. The core of the app is a scrolling list of items which are retrieved from the SQLite database.

listController.js

.controller('ListCtrl', [
  '$scope',
  'dataFactory',
  function($scope, dataFactory) {

    var items = dataFactory.getAllItems().then(function(data){
      $scope.allItems = data;
    });
  
  }
]);

dataFactory.js

.factory('dataFactory', [function($window, $log, $q, $cordovaSQLite, dummyDataGenerator){    
      
  var db_;

  // ...lots of SQLite fun in here
  // cascading async callbacks to load the database and inject dummy data
  var openDB_ = function(){...};
  var createTable_ = function(){...};
  // etc
	   
  var getAllItems = function(){

    var q = $q.defer();
    $cordovaSQLite.execute(db_, sqlSelectString, []).then(
      function(results) {
        $log.log("SQL SELECT successful");
        var i, len, allItems = [];
        for(i = 0, len = results.rows.length; i < len; i++) {
          allItems.push(results.rows.item(i));
        }
        q.resolve(allItems);
      },
      function (err) {
        q.reject(err);
      }
    );
    return q.promise;
  };

  return { getAllItems: getAllItems };
]}); // <-- factory

Initially I was returning the factory straight away. The controller did getAllItems() which ran before the data was ready. The view was initially empty, only showing anything on return to the route after a second getAllItems()

So I tried delaying the return of the factory by adding a factoryReady() function and only calling it once all the internal DB stuff was ready

var factoryReady = function(){
  return {
    getAllItems: getAllItems
  };
};

And now there’s an undefined error as the entire factory is unavailable when first called, rather than getAllItems() simply returning empty-handed. I can see that the SQL database is being correctly written to in due course, but Angular throws an exception before this has finished.

I realise now that this is predictable, I’ve read the post http://stackoverflow.com/questions/16286605/initialize-angularjs-service-with-asynchronous-data but don’t quite understand how to implement the top-ranked answer (by joakimbl)

What’s the best way to expose the service and ensure it’s not called by the controller until the internal async stuff has finished? Do I need to return the ENTIRE service as a promise rather than just the result from getAllItems? I had a go at this but am now confused. Thanks.


#2

Do you need to wrap it in an ionic.Platform.ready(function() {}) maybe?


#3

Hmm I’ll give it a go, thanks. My ionic.Platform.ready is in app.js() at the moment - can I move it into my dataFactory.js file with no issues?


#4

Have a look at https://gist.github.com/borissondagh/29d1ed19d0df6051c56f