Cast to ObjectId failed for user_id

Question

I want to create a thread post that once each user creates a thread it will be map to the User model updating the User document by pushing the newly created thread id into the threads array of the User. But I am encountering an error once I want to create a thread. Please kindly assist

Failed to create thread: Thread validation failed: author: Cast to ObjectId failed for value "user_2TXrt6taAgNcj0meuTHUEuxQ364" (type string) at path "author" because of "BSONError"

I have ensure that the "author" field's value is being assigned correctly and matches the expected data type (ObjectId in this case)

Answer 1

As the error mention, user_2TXrt6taAgNcj0meuTHUEuxQ364 is not a valid object ID. You need to change your mongoose schema so User is of types String

A valid object id will look something like 638c6c2875345eefb8aafa28

In your case,

author: { 
type: String,
ref: "User"
required: true, 
},

And you need to change the User Schema as well.

Answer 2

your schema is correct. the error says

Cast to ObjectId failed for value "user_2TXrt6taAgNcj0meuTHUEuxQ364"

this user_2TXrt6taAgNcj0meuTHUEuxQ364 is not a valid mongoose id. you are probably querying MongoDB with this id and MongoDB is throwing this error.

Answer 3

Hey I'm doing the same threads project so just add this segment in PostThread.tsx inside the post thread

const [userData, setUserData] = useState(null);

useEffect(() => {
  // Fetch user data
  fetchUser(userId)
    .then((user) => {
      setUserData(user);
    })
    .catch((error) => {
      // Handle error
    });
}, [userId]);

after change author to userId.id keep the rest same

const onSubmit = async (values: z.infer<typeof ThreadValidation>) => {
  await createThread({
    text: values.thread,
    author: userId._id,
    communityId: null,
    path: pathname,
  });
});

The root cause of this issue was that you were using the custom id field of your User schema instead of the MongoDB-generated _id field. To resolve the issue, you needed to fetch and use the actual _id value from your user data when creating a thread.

Answer 4

The answer might be really simply - just look at your create-thread -> page.tsx, and look if you pass the right id:

return (
  <>
    <h1 className="head-text">Create thread</h1>
    <PostThread userId={userInfo._id} />
  </>
);

I also wrote id instead of _id and that was the problem - was passing the inner userId instead of the ObjectID.

Answer 5

For me it worked making userInfo._id.toString()