graphql relation mutation

createA.graphql

# Step 1
# To create a B you have to create a A first
mutation {
  createA(
    title: "first A!"
  ) {
    id
  }
}

createB.graphql

# Step 2
# Create a B with a relation to A
mutation makeBOrAnotherCoolFuncName ($aid: ID, $bTitle: String!) {
  createB(
    title: $bTitle
    asId: $aid
  ) {
    id
  }
}

# Variables:
# {
#  "aid": "ID_OF_AN_A",
#  "bTitle": "My first B"
# }

types.graphql

type A @model {
  id: ID! @isUnique
  title: String
  createdAt: DateTime!
  bs: [B!]! @relation(name: "C")
}


type B @model {
  id: ID! @isUnique
  title: String!
  createdAt: DateTime!
  as: A! @relation(name: "C")
}

Login example:
https://github.com/graphcool-examples/react-graphql/blob/master/authentication-with-email-and-apollo/server/src/email-password/authenticate.js