request-body-discriminator-added

What this check detects

A discriminator is a hint on a oneOf / anyOf schema that tells a consumer which of the listed subschemas a payload conforms to, by reading a named property (propertyName) rather than trying each subschema in turn. It is used mainly by code generators and validators to map a value to a concrete type.

Adding a discriminator changes how the request body is interpreted: the named property must now be present and must match one of the mapped subschemas. oasdiff reports it as informational, but review it, because a payload that validated against a branch by structure alone may now be routed by the discriminator value instead.

Example

requestBody:
  content:
    application/json:
      schema:
        oneOf:
          - $ref: '#/components/schemas/Cat'
          - $ref: '#/components/schemas/Dog'

requestBody:
  content:
    application/json:
      schema:
        oneOf:
          - $ref: '#/components/schemas/Cat'
          - $ref: '#/components/schemas/Dog'
        discriminator:
          propertyName: petType

A discriminator now selects which subschema the request body is validated against, based on the "petType" property.

Change its severity or ignore it

To change the severity oasdiff assigns to request-body-discriminator-added, list its id and a level in a severity-levels file, one rule per line. The level can be err, warn, or info, or none to disable the check entirely:

# severity.txt
request-body-discriminator-added err

Then pass it to oasdiff:

oasdiff changelog base.yaml revision.yaml --severity-levels severity.txt

Setting the level to none disables the check, so it is no longer reported at all.