查詢關係分析關係數據不會回來排序使用orderedByAscending

我在查詢關係數據的解析，我希望對象回來，他們被創建的日期排序。我以前使用過此方法，但一直無法使用關係數據獲得有序查詢。查詢返回的順序是隨機的。提前致謝！這裏是我的代碼：查詢關係分析關係數據不會回來排序使用orderedByAscending

PFQuery *postQuery = [PFQuery queryWithClassName:@"Post"]; 
    [roomQuery whereKey:@"name" equalTo:self.postName]; 

    NSError *error; 
    //done on main thread to have data for next query 
    NSArray *results = [postQuery findObjects:&error]; 

    PFObject *post; 

    if ([results count]) { 
     post = [results objectAtIndex:0]; 
     NSLog(@"results were found"); 
    } else { 
     NSLog(@"results were not found"); 
    } 

    PFRelation *commentsRelation = [@"Comments"]; 
    [commentsRelation.query orderByAscending:@"createdAt"]; 
    [commentsRelation.query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) { 
     if (error) { 
      NSLog(@"Error Fetching Comments: %@", error); 
     } else { 
      NSArray *comments = objects; 
    }

來源

2014-01-25 user1681673

我沒有看到任何錯誤，只是閱讀代碼。你可以向我們展示一個評論中的數據樣本嗎？ –

「PFRelation * commentsRelation = [@」評論「];」這段代碼甚至不應該編譯，你能修復它以顯示如何獲得commentsRelation嗎？ –

我有點困惑你的代碼，

您創建一個「postQuery」，並調用它，但從來沒有使用它的任何數據。
還有一個從未分配或使用過的roomQuery。
您正在通過名稱查詢特定帖子。你在控制它的名字嗎？如果沒有，你應該使用ID的
什麼是PFRelation commentsRelation = [@「Comments」];

可能是因爲它只是一個片段，這個東西是在別處處理;然而，對於我的回答，我假設你的「評論」字段是一個「評論」類對象的數組。

選項1：

PFQuery * postQuery = [PFQuery queryWithClassName:@"Post"]; 
[postQuery whereKey:@"name" equalTo:self.postName]; 
// again, possibly an id field would be more reliable 
// [postQuery whereKey:@"objectId" equalTo:self.postId]; 
[postQuery includeKey:@"Comments"]; 
PFObject * post = [postQuery getFirstObject];// no need to download all if you just want object at [0] 
// this will contain your post and all of it's comments with only one api call 
// unfortunately, it's not sorted, so you would have to run a sort. 
NSArray * comments = [post[@"Comments"] sortedArrayUsingComparator: ^(id obj1, id obj2) { 
    return [obj1[@"createdAt" compare: obj2[@"createdAt"]; 
}];

選項2：

也許是更好的選擇是返工你的數據結構，而不是關聯的意見後，你可以在帖子的評論聯繫起來（在解析文檔）

PFQuery * postQuery = [PFQuery queryWithClassName:@"Post"]; 
[postQuery whereKey:@"name" equalTo:self.postName]; 
// again, possibly an id field would be more reliable 
// [postQuery whereKey:@"objectId" equalTo:self.postId]; 

PFQuery * commentQuery = [PFQuery queryWithClassName:@"Comment"]; 
[commentsQuery whereKey:@"parent" matchesQuery:postQuery]; // when creating a comment, set your post as its parent 
[commentsQuery addOrderDescending:@"createdAt"] 
[commentQuery findObjectsInBackgroundWithBlock:^(NSArray *comments, NSError *error) { 
    // comments now contains the comments for myPost 
}];

上述兩種解決方案避免不必要的額外API調用（解析基於呼叫後，所有費用！）。

來源

2014-02-02 16:57:19 Logan

查詢關係分析關係數據不會回來排序使用orderedByAscending

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