Atomic operation on nested array in GraphQL API

[wwwy3y3]

Is your feature request related to a problem? Please describe. We should provide atomic operation like add, remove, set operation for nested array type.

Describe the solution you'd like

type Tag {
  name: String
}

type Book @GQLifyModel(dataSource: "firebase", key: "Book") {
  id: ID! @unique @autoGen
  name: String!
  tags: [Tag]
}

Right now, we can only override the whole field with another array.

We should provide graphQL api like:

mutation {
  # add a new tag
  updateBook(where: {id: "1"}, data: {tags: {add: {name: "new tag"}}}) {
    id
  }
}

Additional context There are things we need to consider, for example:

• In terms of remove, how do we match the element to be removed? Do we only remove one element matched? or all matched?
• Different data-source has different way to handle nested array operation, how do we deal with it? for example:
  • Mongo: https://docs.mongodb.com/manual/reference/operator/update-array/
  • Firestore: https://firebase.google.com/docs/firestore/manage-data/add-data#update_elements_in_an_array