Error: Cannot return null for non-nullable field Post.title-CodePudding

Error: Cannot return null for non-nullable field Post.title. at completeValue (D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:594:13) at executeField (D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:489:19) at executeFields (D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:413:20) at completeObjectValue (D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:914:10) at completeValue (D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:635:12) at completeValue (D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:584:23) at D:\graphql\Graphql-social-media-project\api\node_modules\graphql\execution\execute.js:486:9 at processTicksAndRejections (node:internal/process/task_queues:96:5) at async graphqlMiddleware (D:\graphql\Graphql-social-media-project\api\node_modules\express-graphql\index.js:125:26)

When trying to update the values for post like that:

post.title = PostInput.title;
post.content = PostInput.content;
post.imageUrl = PostInput.imageUrl;
const result = post.save();

My PostInput looked had [object null prototype] before but I got rid of it by:

PostInput = JSON.parse(JSON.stringify(PostInput));

Now, it looks like this:

{
  title: 'eeesss',
  content: 'some real content',
  imageUrl: 'images/4423877f-a37f-46ce-b1bf-db3082d2fe36'
}

My graphql schema look like this:

type Post {
    _id: ID!
    title: String!
    content: String!
    imageUrl: String!
    creator: User!
    createdAt: String!
    updatedAt: String!
}

type User {
    _id: ID!
    name: String!
    email: String!
    password: String
    status: String!
    posts: [Post!]!
}

type AuthData {
    token: String!
    userId: String!
}

type PostData {
    posts: [Post!]!
    totalPosts: Int!
}

input UserInput {
    email: String!
    name: String!
    password: String!
}

input PostInput {
    title: String!
    content: String!
    imageUrl: String
}

type RootQuery {
    login(email: String!, password: String!): AuthData!
    posts(page: Int): PostData!
    post(postId: String!): Post!
}

type RootMutation {
    createUser(UserInput: UserInput): User!
    createPost(PostInput: PostInput): Post!
    updatePost(id: ID!, PostInput: PostInput): Post!
}

schema {
    query: RootQuery
    mutation: RootMutation
}

I don't understand why it says PostInput.title is null when it clearly not.
BTW, the code is completely working the post indeed gets updated but the error is thrown anyway.
I will be glad for any help :)

CodePudding user response：

You need to make sure postInput reach the data, something like this:

if (PostInput) {
  post.title = PostInput.title;
  post.content = PostInput.content;
  post.imageUrl = PostInput.imageUrl;
  const result = post.save();
}

CodePudding user response：

It looks like the issue is with the Post being returned, not PostInput since the message says Cannot return null for non-nullable field Post.title not PostInput.title.

Ensure you code isn't trying to return a post object with a null title.