Redcap longitudinal records break ability to use a foreign key onto masters / external ids

[philayres]

Subsequent arms / events only record the record_id, not any study id field. If we are using longitudinal definitions and populating the foreign key field, we need to look up through the first record using record_id to find the study id, which we should then use to populate the foreign key field.

[philayres]

One approach to simplifying this fix is to add a field longitudinal_study_id automatically during the Redcap project dynamic model setup.

This field then gets written during record capture. If the record has a study id value, use that. If the study id value is nil, look up the matching record id having a study id value and store it.

Then the longitudinal_study_id can be used as the foreign key.

[philayres]

Tests should include the Redcap mechanism for setting up the new field, capturing records and using a foreign_key_name / _configurations.foreign_key_through_external_id option.