This question already has answers here:
findObjectsInBackgroundWithBlock: gets data from Parse, but data only exists inside the block
(2 answers)
Closed 9 years ago.
I'm using Parse.com in my objective-c code to simply check to see if a record is there and return true if it is and false if it's not, here's my code:
- (BOOL)userExists:(NSString*) email{
__block BOOL exists = NO;
PFQuery *query = [PFQuery queryWithClassName:#"User"];
[query whereKey:#"email" equalTo:email];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
// The find succeeded.
NSLog(#"Successfully retrieved %d objects.", objects.count);
// Do something with the found objects
if (objects.count > 0) {
exists = YES;
NSLog(#"Objects > 0");
}else{
exists = NO;
NSLog(#"Objects = 0");
}
} else {
// Log details of the failure
//NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
return exists;
}
This method for some reason is returning NO, even though there is a row that contains that email address I'm looking for. Any advice would be greatly appreciated.
Your block is working in the background, thus, your method is returning the value NO before your block completes the work.
Related
I can currently query a parse class, but can't figure out how to change a labels text if the returned values match the query. I am relatively new to objective C and Parse so my knowledge on the subject is little. My query looks like this (with the text of what i'm trying to achieve underneath).
PFQuery *FTQ0 = [PFQuery queryWithClassName:#"Class1"];
[FTQ0 whereKey:#"Location" equalTo:#"The Shop"];
//Label.text = query (object?)
Thanks in advance.
Here is a solution. You have to be careful though, because there might be many objects that have key Location and equal to The Shop. This is why parse is returning an array of objects. In this case, I pick the first object in the array and display it.
PFQuery *query = [PFQuery queryWithClassName:#"Class1"];
[query whereKey:#"Location" equalTo:#"The Shop"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
Label.text = [NSString stringWithFormat:#"%#", [[objects firstObject] objectForKey:#"WHATEVER YOU WANT TO DISPLAY EX. NAME, LOCATION..."]]
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
For more information please visit https://parse.com/docs/ios/guide
Something like this :
PFQuery *query = [PFQuery queryWithClassName:#"Class1"];
[query whereKey:#"Location" equalTo:#"The Shop"];
[query getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error) {
if (!error && object) {
// Do your stuff
Label.text = [[object objectForKey:#"YOUR KEY"] stringValue];
} else {
// Error or null object
}
}];
In this example the query return only the first object.
Thanks so much for your quick and helpful response! This was an issue that was troubling me allot! The code provided works!
Thanks!
Im trying to work with a script thats in objective c i want to make an int i can access throughout view did load to change settings or the viewcontroller but it doesn't work like swift and i get a null out of the pfquery so i tried to make an array and couldn't get anything out of the query with that as well
what is the best way to set up and int variable and set it in the pfquery then use if statements later on
here is some of my code
__block int setting = 0;
PFQuery *query = [PFQuery queryWithClassName:#"test"];
[query whereKey:#"testActive" equalTo:[NSNumber numberWithBool:YES]];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
// The find succeeded.
NSLog(#"Successfully retrieved %lu scores.", (unsigned long)objects.count);
// Do something with the found objects
for (PFObject *object in objects) {
NSLog(#"%#", object.objectId);
setting = [[object objectForKey:#"testSetting"] intValue];
// When checked in the loop i get all the right data
}
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
// When checked here i get settings = 0 when it should be 1
if (setting == 0) {
self.segmentedControl.selectedSegmentIndex = 0;
} else if (setting == 1) {
self.segmentedControl.selectedSegmentIndex = 1;
}
if (setting == 3) {
[self.segmentedControl setEnabled:YES];
}else {
[self.segmentedControl setEnabled:NO];
}
But when i check the setting int its always 0 but if i log in the loop is gives me the correct number
thanks for your help
Thanks for your help but i figured it out..
findObjectsInBackgroundWithBlock was not completing before i did the if statements
so i moved the code into a new function which i ran when the PFQuery was completed giving me the correct int
When using the PFQuery, if no results are found it just outputs it to the console but does not let me handle the error in the code. I have not found this documented on their site so I hope to seek help here. I am using:
findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
to try to find the objects. I have tried seeing if objects was nil, error was nil, and if objects.count was equal to zero but none of the above worked.
Does anyone know how to handle the case of the result not being in the query using a PFQuery? Thank you.
EDIT 10/10/2015: My Code:
PFQuery *query = [PFQuery queryWithClassName:#"Group"];
[query getObjectWithId:s];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error && [objects count] > 0) {
// The find succeeded.
}
}else if ([objects count] == 0) {
// Should run when there is nothing found
}
else {
// Log details of the failure
}
}];
When I run the query and get no results, nothing in the block runs.
I am creating my own friend network using parse and want to check to see if a friend request has been sent from one user to another. However, it seems that when I query my parse database it takes some time to receive the information and therefore acts as if a friend request had never been made between two users even though the relationship exists already.
//This is the method to test to see if the request has already been sent
-(int) testForFriendRequestBetween: (NSString *) ID1 and: (NSString *) ID2
{
NSString *user1 = ID1;
NSString *user2 = ID2;
PFQuery *query1 = [PFQuery queryWithClassName:#"friendRequest"];
[query1 whereKey:#"requestFrom" equalTo:user1];
[query1 whereKey:#"requestTo" equalTo:user2];
[query1 findObjectsInBackgroundWithBlock:^(NSArray *objects1, NSError *error) {
if (error)
{
a = 0;
NSLog(#"Error with query");
}
else
{
a = objects1.count;
NSLog(#"%i", a);
}}];
return a;
}
//This is where the user types in an email address to search for a friend and I test to see if request already exists
- (IBAction)sendRequest:(id)sender
{
PFUser *currentUser = [PFUser currentUser];
NSString *myID = currentUser.objectId;
//Look in email column and search whatever was typed into the texfield
PFQuery *query = [PFQuery queryWithClassName:#"_User"];
[query whereKey:#"email" equalTo: _typeEmail.text];
[query getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error)
{
//If the user was found
if (!error)
{
//Create a string that reads the unique ID
NSString *friendID = object.objectId;
//Test to see if request already exists
int test1 = [self testForFriendRequestBetween:myID and:friendID];
int test2 = [self testForFriendRequestBetween:friendID and:myID];
if(test1+test2 == 0)
{
NSLog(#"%i", test1+test2);
//Save request to new row
PFObject *request = [PFObject objectWithClassName:#"friendRequest"];
request[#"requestFrom"] = myID;
request[#"requestTo"] = friendID;
request[#"status"] = #"pending";
[request saveInBackground];
//Update label
_requestLabel.text = #"Friend Request Sent";
} else
{
_requestLabel.text = #"Request Already Sent";
}
}
//If user was not found
else
{
//Update label
_requestLabel.text = #"Friend Is Not Registered";
}
}
];
}
The output of this in the console is:
2014-07-07 13:14:25.559 SignIn[11363:70b] 0
2014-07-07 13:14:25.667 SignIn[11363:70b] 14
2014-07-07 13:14:25.730 SignIn[11363:70b] 2
This means that it is first reporting that test1 + test2 = 0. But then it runs the first method and says that the value of test1 is 14 and the value of test2 is 2! Any help would be much appreciated.
Your implementation of testForFriendRequestBetween has a serious bug. You return a value that does not have a valid value. If you make an asynchronous request, like you do with findObjectsInBackgroundWithBlock:, you can't return the result of that call synchronously (i.e. by using return a. Instead, your method should have a callback block with a parameter that contains the data you receive from the query. You call that callback inside the query completion block.
Here's a simple example based on your code. As you see, all the results are processed in the callback blocks. This is the only correct way when you get the data using async calls.
- (void)testForFriendRequestBetween:(NSString *)ID1 and:(NSString *)ID2 callback:(void (^)(NSArray *results))completion {
// configure the query object, etc.
[query1 findObjectsInBackgroundWithBlock:^(NSArray *objects1, NSError *error) {
if(!error) {
// now you can send the query results back to the caller!
callback(objects1);
}
}
}
- (IBAction)sendRequest:(id)sender
{
// set up query, etc.
[query getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error)
{
//If the user was found
if (!error)
{
[self testForFriendRequestBetween:myID and:friendID callback:^(NSArray *results) {
if(results.count == 0) {
// do stuff
}
}];
}
}
}
I am a bit new to Xcode and Parse and am creating a query in a outlet collection. Everything looks fine except I am getting an error stating "Property 'text' not found on object of type 'id'"... Here is my code that I have:
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
// The find succeeded.
NSLog(#"Successfully retrieved %d scores.", objects.count);
// Do something with the found objects
int i = 0;
for (PFObject *object in objects) {
if (i >= [self.EventTitles count]) break;//to make sure we only write up to the max number of UILabels available in EventTitles
(UILabel *) self.EventTitles[i].text = object.objectId;//I assume the "objectId" property of object is an NSString!
i++;
}
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
Can anyone help me so I can get this build to not fail?
Change this:
(UILabel *) self.EventTitles[i].text = object.objectId;
to:
[(UILabel *)self.EventTitles[i] setText:object.objectId];