Interfaces

Interfaces

builder.drizzleInterface works just like builder.drizzleObject, and can be used to define either the primary type or a variant of a table as an interface that other variants implement. The interface's select is planned whenever a field returns the interface, and an implementation's own select is planned when a fragment narrows to it. Selections are not inherited, so an implementation that exposes more columns will need a select of its own.

export const Viewer = builder.drizzleInterface('users', {
  variant: 'Viewer',
  select: { columns: { id: true, role: true } },
  resolveType: (user) => (user.role === 'admin' ? 'AdminViewer' : 'MemberViewer'),
  fields: (t) => ({
    id: t.exposeID('id'),
    user: t.variant('users'),
  }),
});

builder.drizzleObject('users', {
  variant: 'AdminViewer',
  interfaces: [Viewer],
  select: { columns: { permissions: true } },
  fields: (t) => ({
    permissions: t.exposeStringList('permissions'),
  }),
});

Fields can be added to an interface later with builder.drizzleInterfaceField and builder.drizzleInterfaceFields, which take the interface ref (or the table name) like their drizzleObjectField(s) counterparts:

builder.drizzleInterfaceFields(Viewer, (t) => ({
  posts: t.relatedConnection('posts'),
}));

An object type implementing a drizzle interface must be based on the same table. A plain object type that implements one is planned with the interface's table, so fragments on it will select the relations it inherits.