Nested update

An update mutation can change a relationship alongside the record itself, using the same auto-declared fields as a create mutation.

Replacing a relationship

author: auto on PostUpdateWithAuthorInput lets updatePostWithAuthor point the post at a different existing user, with set:

from strawberry import auto


@strawchemy.pk_update_input(Post, include=["id", "title"])
class PostUpdateWithAuthorInput:
    author: auto


@strawberry.type
class Mutation:
    update_post_with_author: PostType = strawchemy.update_by_ids(PostUpdateWithAuthorInput)

mutation {
    updatePostWithAuthor(data: { id: 1, title: "Updated title", author: { set: { id: 2 } } }) {
        id
        title
        author {
            id
            name
        }
    }
}

set: null clears the relationship instead:

mutation {
    updatePostWithAuthor(data: { id: 1, title: "No author", author: { set: null } }) {
        id
        title
        author {
            id
        }
    }
}

set on a to-many field works the same way, replacing the whole collection with the posts named by id:

@strawchemy.pk_update_input(User, include=["id", "name"])
class UserUpdateWithPostsInput:
    posts: auto


@strawberry.type
class Mutation:
    update_user_with_posts: UserType = strawchemy.update_by_ids(UserUpdateWithPostsInput)

mutation {
    updateUserWithPosts(data: { id: 1, name: "Alice", posts: { set: [{ id: 1 }] } }) {
        id
        name
        posts {
            id
            title
        }
    }
}

Adding to a relationship

add attaches existing posts to the collection without touching the rest of it:

mutation {
    updateUserWithPosts(data: { id: 1, name: "Alice", posts: { add: [{ id: 2 }] } }) {
        id
        name
        posts {
            id
            title
        }
    }
}

Removing from a relationship

remove detaches posts from the collection, leaving the records themselves intact:

mutation {
    updateUserWithPosts(data: { id: 1, name: "Alice", posts: { remove: [{ id: 2 }] } }) {
        id
        name
        posts {
            id
            title
        }
    }
}

Creating while updating

mutation {
    updatePostWithAuthor(
        data: { id: 1, title: "Updated title", author: { create: { id: 6, name: "Frank", email: "frank@example.com" } } }
    ) {
        id
        title
        author {
            id
            name
        }
    }
}

posts accepts create the same way, adding new posts to the collection:

mutation {
    updateUserWithPosts(data: { id: 1, name: "Alice", posts: { create: [{ id: 7, title: "New post", content: "..." }] } }) {
        id
        name
        posts {
            id
            title
        }
    }
}

Combining operations

An update can combine add and create:

mutation {
    updateUserWithPosts(
        data: {
            id: 1
            name: "Alice"
            posts: { add: [{ id: 2 }], create: [{ id: 8, title: "Combined", content: "..." }] }
        }
    ) {
        id
        name
        posts {
            id
            title
        }
    }
}

Combining set with create, upsert, add or remove on the same to-many field raises an error:

mutation {
    updateUserWithPosts(
        data: { id: 1, name: "Alice", posts: { set: [{ id: 1 }], add: [{ id: 2 }] } }
    ) {
        id
        name
        posts {
            id
            title
        }
    }
}

You cannot use `set` with `create`, `upsert`, `add` or `remove` in a -to-many relation input