CODEWITHSUNDEEP
sapui5
Chris Gabler
Chris Gabler

Reputation: 179

this.byId() returns undefined

I have two functions in the controller, one of which is used for processing some event, let's say button click.

This one works fine: 

handleUploadPress: function(oEvent) {
			var oFileUploader = this.byId("streamerUploader");
			if (!oFileUploader.getValue()) {
				MessageToast.show("Choose file");
				return;
			}

And this one throws error:

showResponse: function(id, response) {
				this.byId("streamerUploader").someMethod();
			}

In both functions "this" equals event provider, however, this.byId() returns undefined in the second one. What is the reason?

Upvotes: 0

Views: 3015

Answers (1)

Chris Neve
Chris Neve

Reputation: 2424

this does not point to the controller when called from a callback method.

Your handleUploadPress() method, presumably, is an event handler and handles the press of a file upload button. The owner of this method is the controller, and calling this.byId(...) will behave as expected - it will return the component in the view with the specified ID.

However, in your callback method, this is not the controller. The method this.byId is undefined - it's a method defined by SAP UI5 controllers.

What you need to do

Before you send your request with req.then(...), declare a variable whose value will be the this you will need to access, as such:

var that = this;

Then, to use the byId method, go by this variable.

that.byId(...).doSomeMethod();

I advise you read this question and answers to understand more about this in Javascript.

Upvotes: 1

Related Questions