AngularJS/Ionic How to correctly get data from database to display in view? - sql

Question

What is the correct/best approach to get data from a database for something like calendar and its events.
I think there are two possible ways:
1) Should I get all data from the database and save it in a $scope object, so that I access the SQLite db only once and work with the object later on
2) Should I only get the data for the currently selected day of the calendar, and if I want to display another day, I do another sql query.
EDIT: the database is local, so network perfomance is no matter

Answer 1

I think it depends on what is more important for you and how big the data is.
If you are working with a local database you have keep in mind that you always have to do async operations to get data from your database. So you always have a little time (depending on the device performance) where the promises have to get resolved even if its on local db.
My ionic application follows the concept 2 of your options without using any cache. The trick to render correct data is to resolve relevant data before entering the view.
My stateprovider looks like this:
.state('app.messages', {
url: "/messages",
views: {
'menuContent': {
templateUrl: "pathToTemplate.html",
controller: 'ExampleMessageListCtrl'
}
},
resolve: {
messages: function($q,DatabaseService) {
var deferred = $q.defer();
//All db functions are async operations
DatabaseService.getMessageList().then(function (messageList) {
deferred.resolve(messageList);
}, function (err) {
deferred.reject(err);
});
return deferred.promise;
}
},
//Disable cache to always get the values from db
cache:false
In the controller you can access the messages variable via injection:
.controller('ExampleMessageListCtrl', function ($scope,messages) {
var loadMessages = function() {
$scope.messages = messages;
};
...
});
The benefits of this concept with resolving the data before entering the state is that you always get the data which is inside the db without rendering frames with empty data inside, which comes from default data inside the scope variables.
I think options 1 is the right option if you want to display data very quickly. The challenge in this case is to hold your cached data synchronized with the data in the database without loosing much performance, which I think is not very easy.