Use migrate to populate entity_reference with nid I am migrating a D6 site to D8. The D6 site used the "Node Relativity" module, which has been broken for a while. It was used to establish a link between two content types, which I will call meeting and recording. 

Now I am trying to use the migrate module (and friends like migrate_plus) to establish an entity reference to recording in the meeting content type. Here is what I have done: 


In the D8 site, specified the field structure for the two content types. In the meeting content type there is an entity reference for the recording called field_recording_link. 
Exported the configuration into custom modules. I can now create a database from scratch and it creates the content types.
Connected my D6 database to import content. Textfields from the meeting content type do get imported.
Written a custom source module with a prepareRow() method that exposes the NID of the recording nodes (called recording_nid). I can see this NID in the migration.


In the migrate_plus.migration.upgrade_d6_node_meeting.yml file, added the following stanza in the process section: 

field_recording_link: recording_nid


but this does not populate the field. I have also tried:

'field_recording_link/target_id': recording_nid


but that does not work either. I feel as if this ought to be straightforward, but I am pretty stuck. 


Do I need to make a process plugin? If so what should it do? Use PHP to create an entity reference and populate it?
Do I need to call an existing process plugin? If so which one?
Do I have to write a separate .yml file just for this field? If so what would it look like? I have been looking around for examples but have not had much luck.


I would appreciate any advice you have, as well as links to examples of this.
It was straightforward. I had a typo in my YML file. The correct answer was: 

field_recording_link/target_id: recording_nid


The important thing is to set the target_id field, since that is what the entity reference really is.