Local Storage

Persistent Local Storage

You can write to or access the storage using simply ensemble.storage. On the browser, this uses the local storage. On the native apps, it uses the secure storage that's provided to each app by iOS and Android. This stoage is persistent i.e. the data you save will stay there until the user explicitly deletes the storage or the app. This means that you can use storage to share data among multiple screens in your app.

Typically apps store data such as the logged-in user's information, app-level data to cache data from the backend etc.

Storing and Retrieving data

You can store data in the persistent storage by just using the following syntax -

ensemble.storage.myData = {name: {first:'John', last: 'Doe'}};

and to retrieve data, simply access the parameter by name. For example -

  id: nameField
  text: ${ensemble.storage.myData.name.first} ${ensemble.storage.myData.name.last}

or in js -

nameField.text = ensemble.storage.myData.name.first + ' ' + ensemble.storage.myData.name.last;

You can also store and retrieve properties using the set and get methods on ensemble.storage. This is useful when the parameter name is dynamically calculated instead of being known in advance.

ensemble.storage.set('my'+'Data',"{name: {first:'John', last: 'Doe'}");
//to retrieve data
var myData = ensemble.storage.get('my'+'Data');

If the parameter with the same name already exists in the storage, it's value will be overwritten by the new value being set.

Checking if something is in storage

You can check in two ways, either by directly accessing the parameter by name or by using the get method and checking for null.

if ( ensemble.storage.myData != null ) {
  //do something

Deleting data in storage

You can set the parameter to null to remove its value. However if you want to entirely delete it from storage, call the delete method.

ensemble.storage.delete('myData'); //this will remove value referenced by myData and the myData as the key.

Binding to the data in storage

One of the most powerful features of the Ensemble platform is the data binding. It allows you to significiantly reduce the amount of code you have to write and the ensuing complexity by just binding your widgets to the APIs or Storage.

Here we will discuss binding to the ensemble.storage. When you bind a widget to something, the widget gets updated automatically when the thing it is bound to changes.

For example, in the following yaml, nameField.text is bound to data in the storage.

  id: nameField
  text: ${ensemble.storage.myData.name.first} ${ensemble.storage.myData.name.last}

Now somewhere else (mostly in API responses), if you update the myData in storage, the nameField.text will automatically get the new value without you having to do anything.

    url: 'https://myapp.com/data'
    onResponse: |-
      ensemble.storage.myData = response.data; //this will update all the fields that are bound to this parameter in storage

Manually triggering binding updates

Updates due to bindings to the storage are triggered only when you set a parameter on the storage directly.

For example, the following triggers the binding and updates all the fields that are bound to ensemble.storage.myData

ensemble.storage.myData = {name: {first:'John', last: 'Doe'};

However, if you are manipulating the data that is not directly stored in the ensemble.storage, it won't trigger binding.

ensemble.storage.myData.name.first = 'Jane'; //will NOT trigger binding and the `nameField.text` will NOT be updated.

To solve this issue, we set storage parameter back to itself to trigger the update. After doing all the manipulations to myData, set it back to itself

ensemble.storage.myData = ensemble.storage.myData; //this will now update nameField.text and any other fields listening for this change