PF查询未返回结果

时间：2015-12-06 21:56:04

标签： objective-c parse-platform

我真的很困惑为什么我的PFQuery不会返回任何结果。首先让我向您展示我最初做过的事情，这段代码完美无缺。 

-(IBAction)Answer2:(id)sender{

NSString *quizString = [NSString stringWithFormat:@"%i",CategoryLoaded];
NSString *questionString = [NSString stringWithFormat:@"%i",QuestionSelected];
NSString *answerString = [NSString stringWithFormat:@"b"];

PFObject *newAnswerVote = [PFObject objectWithClassName:@"QuizData"];
newAnswerVote[@"quiz"] = quizString;
newAnswerVote[@"question"] = questionString;
newAnswerVote[@"answer"] = answerString;

[newAnswerVote saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
    if (succeeded == YES){

        [newAnswerVote incrementKey:@"Total"];
    }
    else{
    }
}
 ];


PFQuery *queryb = [PFQuery queryWithClassName:@"AnswerStorage"];
[queryb whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
[queryb whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
[queryb whereKey:@"Answer" equalTo: [NSString stringWithFormat:@"b"]];
[queryb getFirstObjectInBackgroundWithBlock:^(PFObject *total, NSError *error){
    [total incrementKey:@"Total"];

    NSString *myVote = total[@"Answer"];

    [total saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (succeeded == YES){
            PFQuery *queryForHighestVoteb = [PFQuery queryWithClassName:@"AnswerStorage"];
            [queryForHighestVoteb whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
            [queryForHighestVoteb whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
            [queryForHighestVoteb orderByDescending:@"Total"];
            [queryForHighestVoteb getFirstObjectInBackgroundWithBlock:^(PFObject *firstAnswerStorageObject, NSError *error){
                if (nil != error) {
                    // query failed
                } else {
                    NSString *highestVote = firstAnswerStorageObject[@"Answer"];
                    if (myVote == highestVote) {

                        [self RightAnswer];
                    } else {

                        [self WrongAnswer];

                    }}}];

        }}];
}];
}

现在这是我正在使用的代码。使用先前使用的相同PFQuery，但稍后使用添加的算法。但是，此查询不会检索任何结果。给我VoteAScore，VoteBScore，VoteCScore和VoteDScore的0值。离开我的错误：

EXC_arithmetic（code = exc_i386_div，subcode = 0x0）

我不知道是什么导致了它。

-(void)GetTotalVotes{

PFQuery *querya = [PFQuery queryWithClassName:@"AnswerStorage"];
[querya whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
[querya whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
[querya whereKey:@"Answer" equalTo: [NSString stringWithFormat:@"a"]];
[querya getFirstObjectInBackgroundWithBlock:^(PFObject *atotal, NSError *error){

    [atotal incrementKey:@"Total"];
    [atotal incrementKey:@"Test"];


    [atotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (succeeded == YES){

            NSUInteger answerATotal = [atotal[@"Total"]intValue];

            VoteAScore = answerATotal;


            [atotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
                if (succeeded == YES){
                }
                else{}
            }];}

        else{}
    }];}];

PFQuery *queryb = [PFQuery queryWithClassName:@"AnswerStorage"];
[queryb whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
[queryb whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
[queryb whereKey:@"Answer" equalTo: [NSString stringWithFormat:@"b"]];
[queryb getFirstObjectInBackgroundWithBlock:^(PFObject *btotal, NSError *error){

    [btotal incrementKey:@"Total"];
    [btotal incrementKey:@"Test"];


    [btotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (succeeded == YES){

            NSUInteger answerBTotal = [btotal[@"Total"]intValue];

            VoteBScore = answerBTotal;


            [btotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
                if (succeeded == YES){
                }
                else{}
            }];}

        else{}
    }];}];

PFQuery *queryc = [PFQuery queryWithClassName:@"AnswerStorage"];
[queryc whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
[queryc whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
[queryc whereKey:@"Answer" equalTo: [NSString stringWithFormat:@"c"]];
[queryc getFirstObjectInBackgroundWithBlock:^(PFObject *ctotal, NSError *error){

    [ctotal incrementKey:@"Total"];
    [ctotal incrementKey:@"Test"];


    [ctotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (succeeded == YES){

            NSUInteger answerCTotal = [ctotal[@"Total"]intValue];

            VoteCScore = answerCTotal;



            [ctotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
                if (succeeded == YES){
                }
                else{}
            }];}

        else{}
    }];}];

PFQuery *queryd = [PFQuery queryWithClassName:@"AnswerStorage"];
[queryd whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
[queryd whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
[queryd whereKey:@"Answer" equalTo: [NSString stringWithFormat:@"d"]];
[queryd getFirstObjectInBackgroundWithBlock:^(PFObject *dtotal, NSError *error){

    [dtotal incrementKey:@"Total"];
    [dtotal incrementKey:@"Test"];


    [dtotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (succeeded == YES){

        NSUInteger answerDTotal = [dtotal[@"Total"]intValue];

        VoteDScore = answerDTotal;

        AllVoteScore = VoteAScore + VoteBScore + VoteCScore + VoteDScore;

        [dtotal saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
            if (succeeded == YES){
            }
            else{}
        }];}

        else{}
    }];}];}







-(IBAction)Answer1:(id)sender{


NSString *quizString = [NSString stringWithFormat:@"%i",CategoryLoaded];
NSString *questionString = [NSString stringWithFormat:@"%i",QuestionSelected];
NSString *answerString = [NSString stringWithFormat:@"a"];

PFObject *newAnswerVote = [PFObject objectWithClassName:@"QuizData"];
newAnswerVote[@"quiz"] = quizString;
newAnswerVote[@"question"] = questionString;
newAnswerVote[@"answer"] = answerString;

[newAnswerVote saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
    if (succeeded == YES){
    }
    else{
    }
}
 ];


PFQuery *querym = [PFQuery queryWithClassName:@"AnswerStorage"];
[querym whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
[querym whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
[querym whereKey:@"Answer" equalTo: [NSString stringWithFormat:@"a"]];
[querym getFirstObjectInBackgroundWithBlock:^(PFObject *total, NSError *error)    {
    [total incrementKey:@"Total"];
    [total incrementKey:@"Test"];


    [total saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (succeeded == YES){
            PFQuery *queryForHighestVotec = [PFQuery queryWithClassName:@"AnswerStorage"];
            [queryForHighestVotec whereKey:@"Quiz" equalTo: [NSString stringWithFormat:@"%i",CategoryLoaded]];
            [queryForHighestVotec whereKey:@"Question" equalTo: [NSString stringWithFormat:@"%i",QuestionSelected]];
            [queryForHighestVotec orderByDescending:@"Total"];
            [queryForHighestVotec getFirstObjectInBackgroundWithBlock:^(PFObject *firstAnswerStorageObject, NSError *error){
                if (nil != error) {
                    // query failed
                } else {


                    [self GetTotalVotes];}
            }];
        }}];
}];





if (VoteAScore > VoteBScore || VoteAScore > VoteCScore || VoteAScore > VoteDScore || VoteBScore > VoteCScore || VoteBScore > VoteDScore){

    Outcome = 0;
}

else if (VoteAScore > VoteBScore || VoteAScore > VoteCScore || VoteAScore > VoteDScore || VoteCScore > VoteBScore || VoteCScore > VoteDScore){

    Outcome = 1;

}

else if (VoteAScore > VoteBScore || VoteAScore > VoteCScore || VoteAScore > VoteDScore || VoteDScore > VoteBScore || VoteDScore > VoteCScore){

    Outcome = 2;


}

else if (VoteBScore > VoteAScore || VoteBScore > VoteCScore || VoteBScore > VoteDScore){

    Outcome = 3;

}

else if (VoteCScore > VoteAScore || VoteCScore > VoteBScore || VoteCScore > VoteDScore){

    Outcome = 4;

}

else if (VoteDScore > VoteAScore || VoteDScore > VoteBScore || VoteDScore > VoteCScore){

    Outcome = 5;

}
switch (Outcome)
{
    case 0:

    OneFraction = VoteAScore/AllVoteScore;
    TwoFraction = VoteBScore/AllVoteScore;
    Margin = OneFraction - TwoFraction;
    InvertedMargin = 1 - Margin;

    AddScore = Margin * 1000;

    ScoreNumber = ScoreNumber + AddScore;

    [self RightAnswer];

        break;

    case 1:

        OneFraction = VoteAScore/AllVoteScore;
        TwoFraction = VoteCScore/AllVoteScore;
        Margin = OneFraction - TwoFraction;
        InvertedMargin = 1 - Margin;

        AddScore = Margin * 1000;

        ScoreNumber = ScoreNumber + AddScore;


    [self RightAnswer];

        break;


    case 2:

        OneFraction = VoteAScore/AllVoteScore;
        TwoFraction = VoteDScore/AllVoteScore;
        Margin = OneFraction - TwoFraction;
        InvertedMargin = 1 - Margin;

        AddScore = Margin * 1000;

    ScoreNumber = ScoreNumber + AddScore;

    [self RightAnswer];

        break;

    case 3:

        OneFraction = VoteBScore/AllVoteScore;
        TwoFraction = VoteAScore/AllVoteScore;
        Margin = OneFraction - TwoFraction;
        InvertedMargin = 1 - Margin;

        AddScore = Margin * 1000;

    ScoreNumber = ScoreNumber - AddScore;

    [self WrongAnswer];

        break;

    case 4:

        OneFraction = VoteCScore/AllVoteScore;
        TwoFraction = VoteAScore/AllVoteScore;
        Margin = OneFraction - TwoFraction;
        InvertedMargin = 1 - Margin;

        AddScore = Margin * 1000;

    ScoreNumber = ScoreNumber - AddScore;

    [self WrongAnswer];

        break;

    case 5:

        OneFraction = VoteDScore/AllVoteScore;
        TwoFraction = VoteAScore/AllVoteScore;
        Margin = OneFraction - TwoFraction;
        InvertedMargin = 1 - Margin;

        AddScore = Margin * 1000;

    ScoreNumber = ScoreNumber - AddScore;

    [self WrongAnswer];

        break;

}}

2 个答案:

答案 0 :(得分：0)

除了代码中的许多问题（请参阅上面的评论）之外，您还必须记住getFirstObjectInBackgroundWithBlock:，正如其名称所暗示的，在后台运行。所以当它将控制权返回给它的调用者时，什么也没发生，只有在稍后才能用结果调用该块。

所以你不能考虑因为那个调用返回了，所以调用了块，它返回的数据已经可用并保存（稍后会发生）。

您需要使用PFQuery调用的同步版本（但如果您从主线程调用它们，这将阻止您的UI），或者更好的是，包含任何依赖于这些调用的结果的逻辑在提供的块中调用，而不是在这些调用之后运行的代码中调用。

答案 1 :(得分：0)

由于您在another question的评论中要求我建议解决此问题，我的回答是：

jcaron是对的：您的代码正在向Parse发送多个查询，并且在回调变量设置之前使用返回变量。因此它们为零，你得到除零例外 您评估查询结果的代码部分只能在所有查询完成后执行。

您可以使用两种方法：

1）按顺序嵌套查询
在主线程中，仅发出alpha。在import（如果成功）的回调中，发出beta等问题，最后在上次查询的回调中，评估结果。
这可行，但由于嵌套在多个级别上，代码看起来会令人困惑，而且由于查询是按顺序发出的，因此速度很慢。

2）同时执行查询
定义一种评估结果的方法，因为它现在可以从代码的不同部分调用。一旦所有查询执行了他们的回调，就必须立即调用它 在主线程中，设置变量querya并将其设置为将同时执行的查询数。然后在主线程中一个接一个地发出查询（比如在代码中）。 虽然您按特定顺序发出查询，但可以按任何顺序调用回调（如果松开连接，则根本不调用）。因此，您的查询的任何回调可能是最后一次回调 要检查哪一个实际上是最后一个，你可以在每个回调中递减querya，当它在某个回调中达到零时，你的方法来评估结果是从这个回调中执行的。
但是你应该知道这是异步代码，它的部分可以或多或少地随时执行。例如，语句queryb不是原子的，如果其中2个语句在2个回调中“同时”执行，__block NSUInteger nrOfExpectedServerResponses可能没有减少2，而只减1。为避免此类危险，您必须将此声明括在nrOfExpectedServerResponses块中，例如nrOfExpectedServerResponses--。

当然，在这两种情况下，您都必须处理所有可能的错误。你可以，例如设置一个超时计时器，如果查询未在合理的时间内完成，您的应用程序将继续运行。

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