Let's have a look at the one of the most common use case "Populating Adaptive form text field based on FDM initialized drop-down value".
Consider a database table agent_rta_data that has 3 columns siteID, agentID and rtastatus, on form initialize I want to initialize a drop-down with the list of agent IDs fetched from the database and based on the user selection of agent ID we will set another field in the form with rtastatus assigned to the selected agent.
Sample Table: agent_rta_data
Step 1: Create a Adaptive form that has a drop-down (element name: agentDropdown) and a text field( element name siteDescription)
Step 3: Go to the sample form created at step 1 and open the code editor for the panel and place the below script on the initialize event.
Note: Make sure you update the FDM operation info as per your FDM. In case you are unaware of the same just create a invoke service action in the visual editor for the FDM and navigate to code editor after that and you will get the FDM operation info.
Yes, this is also a valid approach and it essentially calls FDM in a similar way but with the sample, I have shared, you have modularity to concatenate dropdown display value and even write custom save.
if your Form Data Model returns an array, you can bind those values to a drop-down list using the visual rule editor. You will need to use the Set Options method as shown in this screenshot. In this case, the Display value and Data Value are bound to the same element but in real-life use case Data value will typically be id