Error in import mapping for JSON structure

In crash course, for step 4.2.3 I am getting an error as shown in the attachments. I am following exactly the same steps. I could not figure out this one. My Mendix Studio Pro version is 8.16.0.
4 answers

Hi Naaven,

There are 2 things you could do here:

  1. Change the entities (department and employee) in your domain model to persistent entities instead of non-persistent entities. (Open entity and on the top left there's a radio button to change it)
  2. Instead of 'finding by key, you can choose for creating an object and build the logic to check whether it's a new object or an object that has been changed by using a validation microflow. 

The first option is the easiest one, but it's up to you to see what works best for you.

Hope this helps. With kind regards,



Hi Naveen,

If you open the Department and Employee entities, you can set it to a persistable entity (see screenshot)

With kinds regards,

Bryan de Wit


Hello Bryan,

Thanks for your response.

I tried Option 2, as I am not aware of how to perform Option 1 (if possible attach a screenshot)

I got below error and also I have put the dialogue screenshot.

Previously, when I had selected ‘Find an object (by key)’. I got an error as shown below.


Hi Naveen,


For the option 1 (as mentioned by Bryan) you need to go to the domain model of the module.

So not in the Import Mapping.

There you can select the entity itself and open the properties (and you will see what he is showing in his screenprint).


Hope that I could help!