How to get DataSource length in react-native?

Question

How do I get the DataSource's length of a ListView?

Suppose I have the following declaration:

const ds = new ListView.DataSource({ rowHasChanged });
...
someObjectsDs = ds.cloneWithRows(someObjectsArray);

I've tried someObjects.length but this returns me undefined.

Answer 1

You can view the amount of rows to be rendered by calling

someObjectsDs.getRowCount()

Official documentation

Answer 2

You can either dig into the datasource object to find the data and grab the length or you can set the data as a property of the component and refer to that:

this.someObjectsArray = someObjectsArray;
someObjectsDs = ds.cloneWithRows(this.someObjectsArray);

Now you will be able to do this.someObjectsArray.length, just make sure you're updating this variable anytime you're updating the datasource.