Question

如何避免不同的用户将同一个字符串保存到同一列中？如果已经创建了对象，则需要检查特定列...

我没有为PFUser类尝试这个，检查重复的用户，默认情况。

任何代码线索，启动示例？

下面是我保存对象的代码。字段_channelName是无法复制的字段，必须在保存之前进行检查。

- (IBAction)addButton:(id)sender {

// Create a new Post object and create relationship with PFUser
PFObject *newPost = [PFObject objectWithClassName:@"Channel"];
[newPost setObject:[_textView text] forKey:@"about"];
[newPost setObject:[_channelName text] forKey:@"name"];
[newPost setObject:[_enterKey text] forKey:@"enterkey"];
[newPost setObject:[PFUser currentUser] forKey:@"owner"]; // One-to-Many relationship  created here!

NSData *imageData = UIImageJPEGRepresentation(self.channelImage.image, 0.8);

PFFile *imageFile = [PFFile fileWithName:@"Image.jpg" data:imageData];
[newPost setObject:imageFile forKey:@"image"];

// Set ACL permissions for added security
PFACL *postACL = [PFACL ACL];
[postACL setPublicReadAccess:YES];
[PFACL setDefaultACL:postACL withAccessForCurrentUser:YES];
//PFACL *postACL = [PFACL ACLWithUser:[PFUser currentUser]];
[postACL setPublicReadAccess:YES];
[newPost setACL:postACL];


// Save new Post object in Parse
[newPost saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
    if (!error) {
        [self dismissViewControllerAnimated:YES completion:nil];
        // Dismiss the viewController upon success

    } else {

        //implement upload error message
    }
   }];

  [self dismissViewControllerAnimated:YES completion:nil];

}

Thanx和欢呼!!!!

Answer 1

您可以通过两种不同的方式实现此目的。您可以使用云代码，也可以在客户端执行此操作。

云代码看起来像这样：

Parse.Cloud.beforeSave("YourClass", function(request, response) {
var query = new Parse.Query("YourClass");
query.equalTo("uniqueColumn",request.object.get("uniqueColumn"));
query.first({
    success: function(object) {             
        if (object){            
            var currentUser = request.object;
            if (currentUser.id === object.id) { // if it already belongs to the user it's good
                response.success();
            } else { // otherwise it already exists and it belongs to someone else
                response.error("uniqueColumn exists");
            }
        } else { // If the object doesn't exist at all it's available
            response.success();
        }
    },
    error: function(error) {
        response.error("Could not validate uniqueness for this uniqueColumn.");
    }
});     
});

您可以使用findObjectsInBackgroundWithBlock方法在客户端执行此操作，并检查返回的数组上的count是否大于0.这样看起来像这样：

PFQuery *query = [PFQuery ...];
[query whereKey:@"name" equalTo:[_channelName text]];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (objects.count > 0) {
        // Not unique, name already exist, handle it here
    } else {
        // Name is unique, proceed to save your object here

        // Create a new Post object and create relationship with PFUser
        PFObject *newPost = [PFObject objectWithClassName:@"Channel"];
        [newPost setObject:[_textView text] forKey:@"about"];
        [newPost setObject:[_channelName text] forKey:@"name"];
        [newPost setObject:[_enterKey text] forKey:@"enterkey"];
        [newPost setObject:[PFUser currentUser] forKey:@"owner"]; // One-to-Many relationship  created here!

        NSData *imageData = UIImageJPEGRepresentation(self.channelImage.image, 0.8);

        PFFile *imageFile = [PFFile fileWithName:@"Image.jpg" data:imageData];
        [newPost setObject:imageFile forKey:@"image"];

        // Set ACL permissions for added security
        PFACL *postACL = [PFACL ACL];
        [postACL setPublicReadAccess:YES];
        [PFACL setDefaultACL:postACL withAccessForCurrentUser:YES];
        //PFACL *postACL = [PFACL ACLWithUser:[PFUser currentUser]];
        [postACL setPublicReadAccess:YES];
        [newPost setACL:postACL];

        [newPost saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
            if (!error) {
                [self dismissViewControllerAnimated:YES completion:nil];
                // Dismiss the viewController upon success

            } else {

                //implement upload error message
            }
           }];

          [self dismissViewControllerAnimated:YES completion:nil];
        }
    }
}];

//...

解析iOS对象重复

1 个答案: