References

[groenroos]

The behaviour around reference fields has become a bit muddy. Go through the entire app and the MongoDB driver to ensure all reference fields behave as advertised, and make sense code-wise.

[groenroos]

General outline of expected functionality:

• Reference fields should not be implied; they must be explicitly set in the model, complete with the collection they refer to
• Each field should be able to contain n number of references
  • MongoDB can handle this natively as an array
  • Drivers for less flexible relational databases may need to abstract away a relations table

GET /data

• In the returned data, each reference should be expanded to the corresponding object
  • There should be a hard limit on how many levels will be expanded (3? 10?)
  • Also a way to detect and prevent recursive references
  • By default, always return an array of objects. Add a single key for the model if the user wants to force a direct object
• In filtering in URL patterns, only filtering by the stored IDs needs to be supported. CSV of IDs should be treated as an OR

POST /data

• If the posted value for the reference field is a string, or an array of strings, assume it's an object ID
  • In strict mode, return an error if it's not a valid ID
• If the posted value is a (JSON) object, or an array of objects, create a new entry based on the values
  • Need to guard against a POST request with multiple reference fields, where the first one succeeds, but the second one fails validation; this should not result in a situation where the overall request fails, but that one straggler entry is retained in the referenced collection
  • Surface a config value for max number of records created on the fly via a reference field, with a sensible default
• When modifying an existing record, overwrite any existing value with whatever is sent, if it's sent
  • Dropped references should not result in deleted records

DELETE /data

• Records to be deleted can be filtered the same as above
• Referenced records should not be deleted automatically