@Rahulan Mahendra Is this for integration purposes or what exactly are you trying to achieve?

If the data needs to just be readable you could use the Query Designer to combine the data of your two entities or if you are not on 22R2 yet a quick report might be another option as these get exposed as REST APIs as well.

@Jonas Feigl 

Customer will eventually use the API with our boomi integration, but their main goal is to get a SINGLE GET method from the Custom Projection's API to return ALL columns in the table.

Is there any other way to achieve this in App 10 aurena from custom projection? 

Will the above method work for integration as well?

@Rahulan Mahendra Ah this is on Apps10. Unfortunately using Query Designer is then not an option. Having said that you should still be able to create a Quick Report that contains the data you need. That Quick Report will automatically be exposed as a REST API which should allow you to do what you need. You do not have to do any Projection Configuration for this to work.

And yes, Quick Reports (as well as Query Designer in IFS Cloud) can be consumed in integrations as well.

One important note: The ID of the Quick Report is a randomly generated number and this number is part of the REST API Endpoint Name. To make sure the endpoint has the same name on all of your environments (i.e. TEST, PROD, etc.) make sure to transfer the Quick Report between environments using an ACP (Application Configuration Package) rather than manually creating the Quick Report on each environment.