Interfaces

builder.prismaInterface defines a GraphQL interface backed by a contract model. It mirrors builder.prismaObject: same options, but produces an InterfaceRef that other prismaObjects can implement.

Declaring an interface

const personIface = builder.prismaInterface('User', {
  name: 'Person',
  fields: (t) => ({
    id: t.exposeID('id'),
    firstName: t.exposeString('firstName'),
    lastName: t.exposeString('lastName'),
  }),
});

A prismaObject can implement the interface as long as it's backed by the same contract model:

builder.prismaObject('User', {
  interfaces: [personIface],
  fields: (t) => ({
    email: t.exposeString('email'),
  }),
});

The plugin's onTypeConfig hook propagates the interface's contract model onto the implementing object — so even a plain builder.objectType that implements a prismaInterface benefits from auto-include. The schema build fails fast if a prismaObject claims a different model than the interface it implements.

Extending an interface

prismaInterfaceField and prismaInterfaceFields extend an interface with fields that need column dependencies — analogous to prismaObjectField(s) on prismaObject:

builder.prismaInterfaceField(personIface, 'displayName', (t) =>
  t.string({
    select: ['firstName', 'lastName'],
    resolve: (person) => `${person.firstName} ${person.lastName}`,
  }),
);

If you pass the contract model name as a string, the plugin looks up the registered interface. If only an interface variant is registered (no default), pass the ref or the variant name explicitly — otherwise Pothos core throws an unresolved-ref error at schema build.

Variants on interfaces

Just like prismaObject, prismaInterface accepts variant: '...' to register a second interface backed by the same contract model:

builder.prismaInterface('User', {
  variant: 'PublicPerson',
  fields: (t) => ({ id: t.exposeID('id') }),
});