解析-多对一查询

Question

I have a query that gets latest posts by users. Each post has an "Owner" field that has the "ObjectId" of the account that created it. I do this because I want to also display the username of the person who created the post - which is found in the User table.

I looked at the Parse documentation for Queries and came up with this (modeled after one of their examples):

    var query = PFQuery(className:"Post")
    query.orderByDescending("createdAt");

    var innerQuery = PFQuery(className: "User")
    innerQuery.whereKey("objectId", matchesQuery: query)

Then I run the findObjectsInBackgroundWithBlock . I don't think I'm getting the information from the User table to get the name of the person who posted the post.

I looked at the object that contains the information for the post but I don't see the information for the user in that object. What am I doing wrong?

Here are screenshots of the headers of my two tables:

POST:

USER:

Thanks!

Answer 1

I think the problem as that you refer to the user table in the query as "PFQuery(className: "User")". But if you use the built in user table, it's name is actually "_User". So use that, or even simplier, use:

var innerQuery = PFUser.query()

Answer 2

Try this

    var class = PFQuery(className:"Post")
    var finduser:PFQuery = PFUser.query()
    finduser.whereKey("objectId", equalTo: class.objectForKey("owner").objectId)
    finduser.findObjectsInBackgroundWithBlock{
                (objects:[AnyObject]!, error:NSError!)->Void in
                if (error == nil){
                    if let userObjects = objects {
                        let UserResult = (userObjects as NSArray).lastObject as? PFUser
                        if let user = UserResult {
                           println(user.username)
                            }
                    }
               }
     }