iOS解析框架嵌套查詢

Question

我有兩個表格TrendingUsers和Follow 。 所需的功能就像從TrendingUsers表中獲取用戶並願意關注，前提是獲取的用戶不在用戶關注列表中。 如果用戶已經被關注，則跳過。

Follow表具有follower和leader列。

PFQuery *followTableQuery = [PFQuery queryWithClassName:@"Follow"];
[followTableQuery whereKey:@"follower" equalTo:[PFUser currentUser] ];
[followTableQuery whereKey:@"leader" equalTo:@"fetchedUserObject" ];
[followTableQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (!error) {
        if (objects.count) {
          //if following objects array will have single object
        }
        else
        {
            //not following to @"fetchedUserObject" user
        }

    }
  }
 ];

這將確認我currentUser是否關注@"fetchedUserObject"用戶。 現在，我要將其集成到TrendingUsers表查詢中，以僅獲取currentUser未關注的用戶。

Answer 1

您可以簡單地使用嵌套查詢，Parse的文檔通常是一個很好的起點。 這是一個示例代碼，據我對您的問題的理解，這應該可以解決問題。

//This is our current user
PFUser *user = [PFUser currentUser];

//The first query, querying for all the follow objects from the current user
PFQuery *followingQuery = [PFQuery queryWithClassName:@"Follow"];
[followingQuery whereKey:@"follower" equalTo:user];

//Now we query for the actual trending users, but we do not want the query to return the users (who are in the @"leader" key) that have been found by the first query
PFQuery *trendingQuery = [PFQuery queryWithClassName:@"TrendingUsers"];
[trendingQuery whereKey:@"objectId" notEqualTo:user.objectId]; //don't return the current user
[trendingQuery whereKey:@"objectId" doesNotMatchKey:@"leader" inQuery:followingQuery]; //I'm supposing that @"leader" is containing the objectId of the specific user that is part of the follow object with the current user
[trendingQuery setLimit:1000];
[trendingQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
{
    //...
}];

我可能還沒有完全理解您的數據結構，因此您可能不得不交換上述代碼中的一個或多個鍵，但是基本上，這就是您要執行的操作。