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Version: v18.0.0

Disallowed Types for `id` Fields

If you see an error from the compiler that reads something like:

Disallowed type `String` of field `id` on parent type `Foo` cannot be used by Relay to identify entities

This means that your GraphQL schema defines an object with a field named id that doesn't have a valid type. Valid types for this field are ID or ID! unless configured otherwise. While there may be a valid reason in your application to have that field defined that way, the Relay compiler and runtime will mishandle that field and cause refresh or data updating issues.

Disallowing id fields without type ID​

Recall that Relay uses Object Identification to know which GraphQL objects to refetch. In the usual case, those GraphQL objects implement the Node interface and thus come with an id field with type ID. However, there are types in your GraphQL model that may not require unique identification. For that reason, Relay (by default) does not restrict object definitions, allowing id fields with non-ID types (e.g. String) to be defined.

This poses a bit of difficulty to both Relay's compiler and runtime. In short, the runtime and compiler only properly handle id fields as defined by the Node interface. Any selections made with non-Node id fields will likely exhibit undesirable and unintended Relay behavior on your components (e.g. components not re-rendering on re-fetched data).

The significance of the ID type​

Global Object Identification in GraphQL) is what underlies Relay's Object Identification. The id field supplied by the Node interface is specified to be a unique identifier that can be used for storage or caching.

Fix: Define your id fields as ID​

To ensure Relay correctly manages objects fetched to your application, here are two recommended courses of action:

  • Ensure all fields named id are typed with ID
  • Rename any fields named id (with a type that isn't ID) to a different name (e.g. special_purpose_id)

If your application truly requires that id field's definition to remain as-is and you are aware of the problems that may arise, you can add your GraphQL type and the type of its id field to the allowlist in nonNodeIdFields of the Relay Compiler's Configuration. Note that this will only bypass the error for that combination of object type and id field type.

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