Data Sources are used in the App Builder to allow you to publish lists of data required for your Forms and Screens. For instance, you might use a Data Source to populate a drop down list on a Form with your product information.
When you click the “Data Sources” link found in the “App Builder” menu, you will be taken to the Data Source list page. The list page shows all available Data Sources. You can sort these and also filter using the Search box.
Creating a Data Source is easy:
Use the “add new” option available in the options bar.
Enter a name for the Data Source.
This name will show in the various Screen designers so you should try to be descriptive so you can identify one Data Source from another.
External Id is an optional field that you can use to store an identifier from your existing systems. For instance, this might be the unique client ID from your database. This gives you a simple way to link Data Sources to your existing system data sets.
Hit the Create button to continue onto the Rows screen.