Regular Dropdown (Pulling from DataSource)

1. Double click on dropdown field in the data source.

2. Select Fx button for Default value.

3. Select Insert field or group.

4. Select secondary xml from data source.

5. Select “value” and click on ok.

For a cascading dropdown:

You have to add the rule and follow these steps,

1. Rules -> ‘Add’ - > ‘Add Action’.

2. Select ‘Set a field value’ option in first dropdown in Action.

3. Select your field with help of ‘Select a Field or Group’ option in ‘Field’.

4. Select your external data source list value in ‘Value’.

This rule you can apply in OnLoad or whenever you will get external data source values.