Populate fields from identity claims.

npm install --save graphql-claim-transformer

Edit amplify/backend/api/<YOUR_API>/transform.conf.json and append "graphql-claim-transformer" to the transformers field.

"transformers": [
    "graphql-claim-transformer"
]

Append @claim to target fields.

type Todo @model {
  id: ID!
  title: String!
  description: String
  foo: String @claim(name: "bar")
}

In the above example the create and update mutations will set the foo field to the value of the bar claim on the user identity object ($ctx.identity.claims.get("bar")).