Customize data model identifiers

Identifiers are defined using the .identifier() method on a model definition. Usage of the .identifier() method is optional; when it's not present, the model will automatically have a field called id of type ID that is automatically generated unless manually specified.

const schema = a.schema({
  Todo: a.model({
    content: a.string(),
    completed: a.boolean(),
  .authorization(allow => [allow.publicApiKey()]),

const client = generateClient<Schema>();
const todo = await client.models.Todo.create({ content: 'Buy Milk', completed: false });
console.log(`New Todo created: ${todo.id}`); // New Todo created: 5DB6B4CC-CD41-49F5-9844-57C0AB506B69

If you want, you can use Amplify Data to define single-field and composite identifiers:

Single-field identifier with a consumer-provided value (type: id or string, and must be marked required)
Composite identifier with a set of consumer-provided values (type: id or string, and must be marked required)

Single-field identifier

If the default id identifier field needs to be customized, you can do so by passing the name of another field.

const schema = a.schema({
  Todo: a.model({
    todoId: a.id().required(),
    content: a.string(),
    completed: a.boolean(),
  .identifier(['todoId'])
  .authorization(allow => [allow.publicApiKey()]),

const client = generateClient<Schema>();
const { data: todo, errors } = await client.models.Todo.create({ todoId: 'MyUniqueTodoId', content: 'Buy Milk', completed: false });
console.log(`New Todo created: ${todo.todoId}`); // New Todo created: MyUniqueTodoId

Composite identifier

For cases where items are uniquely identified by more than a single field, you can pass an array of the field names to the identifier() function:

const schema = a.schema({
  StoreBranch: a.model({
    geoId: a.id().required(),
    name: a.string().required(),
    country: a.string(),
    state: a.string(),
    city: a.string(),
    zipCode: a.string(),
    streetAddress: a.string(),
  }).identifier(['geoId', 'name'])
  .authorization(allow => [allow.publicApiKey()]),

const client = generateClient<Schema>();
const branch = await client.models.StoreBranch.get({ geoId: '123', name: 'Downtown' }); // All identifier fields are required when retrieving an item

Modeling relationships

Customize secondary indexes