ios - 只允许一个 PFUser 有一个 PFObject

Question

我试图做到这一点，一旦 PFUser 或 client 创建了一个 PFObject，他们就不能再创建/创建一个。

这里我展示了 PFObject 是如何创建的:

-(IBAction)New:(id)sender
{
    PFObject *New = [PFObject objectWithClassName:@"client"];
    PFUser *user = [PFUser currentUser];
    [New setObject:user forKey:@"user"];
    [New setObject:[[self Name] text] forKey:@"name"];
    [New setObject:[[self Team] text] forKey:@"team"];
    [New setObject:[[self Points] text] forKey:@"points"];
    [New setObject:[[self Height] text] forKey:@"height"];
    [New setObject:[[self Weight] text] forKey:@"weight"];
    [New setObject:[[self Position] text] forKey:@"position"];
    [New setObject:[[self Game] text] forKey:@"game"];
    [New setObject:[[self Hometown] text] forKey:@"hometown"];
    [New setObject:[[self Birthday] text] forKey:@"birthday"];
  //  [New setObject:[[self Bio] text] forKey:@"bio"];

    NSData *imageData = UIImageJPEGRepresentation(PlayerImage.image, 0.8);
    NSString *filename = [NSString stringWithFormat:@"%@.png", Name.text];
    PFFile *imageFile = [PFFile fileWithName:filename data:imageData];
    [New setObject:imageFile forKey:@"imageFile"];

    [New saveInBackground];
    NSLog(@"Object Added");
}  

通过这段代码，PFObject 被添加到 PFUser 中，现在我需要一种方法来使 User 不能创建另一个 PFObject

Answer 1

您应该使用 Cloud Functions 来实现它。

• > Cloud Functions
• > Calling Cloud Functions in iOS

在您的 Cloud Function 中，您可以检查用户是否已经设置了 client，然后执行更新而不是添加，或者只返回错误。

云代码示例，在 iOS 中无需更改，如果当前用户已有“客户端”，则简单地阻止保存“客户端”:

// returns an error if a client is already set on the user
Parse.Cloud.beforeSave("client", function (request, response) {
    var user = request.user;
    user.fetch().then(function (user) {
        if (user.get("client")) {
            response.error("user already has a client record");
            return;
        } else {
            response.success();
            return;
        }
    }, function (error) {
        response.error(error);
    });
});

// links the client to the user if the save was allowed
Parse.Cloud.afterSave("client", function (request, response) {
    var user = request.user;
    user.set("client", request.object);
    user.save().then(function () {
        response.success();
    },
    function (error) {
        response.error(error);
    });
});