dotted path type check

Q Is the middle segment of a dotted field path (entity.Shot.code) validated against anything?

Endpoint GET /entity/versions?fields=... ; POST /entity/versions/_search

Docs claim Dotted notation entity.EntityType.field is documented for ?fields and for filters. Nothing says what the middle segment is checked against.

Actual

Version.entity valid_types: ["Asset","Level","MocapTake","Reel","ShootDay","Shot","Sequence","Delivery","Launch","CustomEntity29","Camera","CustomEntity19","Slate","SourceClip"]
Version.sg_task valid_types: ["Task"]
control Version links Shot 'sh010_0010'

=== READ: the path in the projection. api3_array, api3_hash and GET ?fields agreed on every row.
  entity.Shot.code       valid_types member, the row's own type       200  "sh010_0010"
  entity.Asset.code      valid_types member, not the row's type       200  null
  entity.Sequence.code   valid_types member, not the row's type       200  null
  sg_task.Task.content   valid_types member of the other field        200  null
  entity.Task.content    real type and field, outside valid_types     200  key absent, attributes ['code']
  sg_task.Shot.code      real type, outside sg_task valid_types       200  key absent, attributes ['code']
  entity.Bogus.code      type does not exist                          200  key absent, attributes ['code']
  entity.Shot.bogusfield field does not exist on Shot                 200  key absent, attributes ['code']

=== FILTER: the same paths on the left of a condition, baseline 100 Versions
  entity.Shot.code is <the control's own code>       -> 200  3 rows
  sg_task.Task.content is <a linked Task's content>  -> 200  1 row
  each of the six paths above that named a real type, is 'ZZZNOPE' -> 200  0 rows
  entity.Bogus.code is 'ZZZNOPE'      -> 400
    {"status":400,"code":103,"title":"API read() Version.entity.Bogus.code doesn't exist.",
     "source":{"Version.entity.Bogus.code":" does not exist. Value: {\"path\" => \"entity.Bogus.code\",
     \"relation\" => \"is\", \"values\" => [\"ZZZNOPE\"]}"},"detail":null,"meta":null}
  entity.Shot.bogusfield is 'ZZZNOPE' -> 400
    "API read() Version.entity.Shot.bogusfield doesn't exist."

Teaches

• Two parsers, two rules. A projection checks the middle segment against the field's valid_types; a filter checks it against the site schema and ignores valid_types.

  path	in ?fields	on the left of a filter
  middle in valid_types, leaf real	the value, or null when the row links another type (field_types/entity)	evaluated
  middle a real type outside valid_types	key absent, 200	200, 0 rows here
  middle names no type	key absent, 200	400 API read() Version.entity.Bogus.code doesn't exist.
  leaf missing on the middle type	key absent, 200	400 API read() Version.entity.Shot.bogusfield doesn't exist.

• A template that writes entity.Asset.code against a Shot is not an error a client can catch on read. It is null while the type is a valid_types member and the key is gone once it is not, which is the same quiet drop a bogus ?fields name gets (probe 004). Read the link out of relationships and branch on data.type rather than asking for a path per type.

• To check a path before shipping it, send it once as a filter. The type and the leaf are both validated there and the 400 names the whole path, Version.entity.Bogus.code, at code: 103.

• api3_array, api3_hash and GET ?fields returned the same key and the same value for all eight paths, so the vendor Content-Type switches nothing here either (probe 004).