JSON Extension File
Here is a simple example to illustrate. Suppose you have a project that infers a list of Metro Stations. These stations are inferred in some way by Excel or Word rules. You wish to use a drop-down to allow the user to select one of those stations.
You decide to use the much-downloaded educational example called Dynamic Options from Instances which you found in the OPA Hub Shop. So far so good. You look at the example Project and you see this:
Cool. It’s a demonstration of a dynamic options list (at the bottom) driven by the entity instances (at the top). And the console shows some cool output to highlight the construction of the list. On the left, you can see that the interview is made up of two Screens. Excellent. Then you decide to split the interview into three Screens – separating the Instances from the Selection. Sounds really cool and a better layout. Now you see this in the Debugger:
Which I think you will agree, is sub-optimal. Our extension just fails miserably. But now, it’s opm.extension.data.json to the rescue. We create this file in the resources folder and populate it according to our needs. In this case, we add – and this is required for any entity attributes – the relationship name (the technical name, not the textual name) and then we declare any attributes we want. So our file looks like this: