Called relation() on non-relation field even when field is relation.

[omairvaiyani]

I've noticed this bug on several occasions since upgrading to 2.2.0. It tends to happen after the object has been saved.

Uncaught internal server error. [Error: Called relation() on non-relation field following] Error: Called relation() on non-relation field following
    at ParseUser.relation (/Users/~/Documents/github/~/node_modules/parse/lib/node/ParseObject.js:579:17)

Tried with Parse SDK 1.7.1 and 1.8.1. Anyone else experiencing this issue?

[gfosco]

What is in the _SCHEMA collection record for this class & key?

[omairvaiyani]

@gfosco

It's for _User

{
    "_id" : "_User",
   ....
    "followers" : "relation<_User>",
   ....
}

Calling user.relation('followers') works fine until the object is saved, after which it says that followers is a non-relation field.

[gfosco]

Can you provide additional code... where are you calling it twice?.. Writing a failing test case would really be valuable here.

[omairvaiyani]

Sure thing - The following is the simplest cloud function which fails:

/**
 * @CloudFunction Follow User
 *
 * Adds user to currentUser' 'following'
 * relation,
 * Sets Jobs to handle follow stats and
 * followed user's follower's relation.
 *
 * param {String} userIdToFollow
 */
module.exports.followUser = function (request, response) {
    var currentUser = request.user,
        userIdToFollow = request.params.userIdToFollow,
        userToFollow = new Parse.User();

    if (!currentUser && request.params.currentUserId) {
        currentUser = new Parse.User();
        currentUser.id = request.params.currentUserId;
    }

    if (!currentUser) {
        return response.error("You must be logged in.");
    }
    if (!userIdToFollow) {
        return response.error("Please send a userIdToFollow.");
    }

    userToFollow.id = userIdToFollow;


    currentUser.relation('following').add(userToFollow); // this works

    currentUser.saveAsUser(currentUser)
        .then(function () {

          currentUser.relation('following'); // This fails (it's no longer needed here as I've refactored the code, but the error is still an issue in other more complicated functions

            return Parse.Promise.when(
                UserEvent.newEvent('followed', userToFollow, currentUser),
                JobQueue.createJob(JobQueue.jobs.postFollowProcessing, {
                    user: currentUser,
                    userFollowed: userToFollow
                }, JobQueue.priorityLevel.high)
            );
        })
        .then(function (userEvent) {
            response.success({
                userEvent: userEvent
            });
        }, function (error) {
            response.error(error);
        });
};

I've just confirmed that the error subsides when I revert from 2.2.0 down to 2.1.6.

[flovilmart]

what's that  .saveAsUser function?

[omairvaiyani]

Hi @flovilmart, it's a helper function:

Parse.Object.prototype.saveAsUser =  function (user, changes)  {
       return this.save(changes || null, {sessionToken:user.getSessionToken()});
};

[omairvaiyani]

Excellent, thank you! This was stopping me from upgrading past 2.1.6!

[borekwa]

Hey @flovilmart, I'm experiencing a similar issue to this one, as are some other users. See this issue. any thoughts?