Core Data saves object even when validation fails - iphone

Question

I've included the function that is handling all of the save functionality.
Here's my problem.
I am grabbing 5 input values and saving it as a CoreData Log Entity.
Even when the Log object fails to validate, it is still being saved when I back out of the form and look at the table view.
How can I force Core Data to only save the object once it's validated?
-(void) saveLog {
NSManagedObjectContext *managedObjectContext = [(AppDelegate_Shared *)[[UIApplication sharedApplication] delegate] managedObjectContext];
FormPickerCell *bloodPressure = (FormPickerCell *) [self.formController fieldAsObject:#"bloodpressure"];
NSInteger systolic = [(PressureDataSource*)bloodPressure.pickerCellDelegate selectedSystolicPressureForFormPickerCell:bloodPressure];
NSInteger diastolic = [(PressureDataSource*)bloodPressure.pickerCellDelegate selectedDiastolicPressureForFormPickerCell:bloodPressure];
NSLog(#"bp is %d / %d", systolic, diastolic);
NSLog(#"date is %#", [self.formController valueForField:#"date"]);
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss ZZZ"];
if (self.isNewLog && !self.validationHasFailed) {
self.log = [NSEntityDescription
insertNewObjectForEntityForName:#"Log" inManagedObjectContext:managedObjectContext];
}
NSString *heartRate = [[self.formController valueForField:#"heartrate"] stringByReplacingOccurrencesOfString:#" bpm" withString:#""];
NSNumberFormatter * f = [[NSNumberFormatter alloc] init];
[f setNumberStyle:NSNumberFormatterDecimalStyle];
self.log.created = [NSDate date];
self.log.notes = [self.formController valueForField:#"notes"];
self.log.systolic = [NSNumber numberWithInteger:systolic];
self.log.diastolic = [NSNumber numberWithInteger:diastolic];
self.log.stressLevel = [self.formController valueForField:#"stresslevel"];
self.log.logDate = [dateFormatter dateFromString:[self.formController valueForField:#"date"]];
self.log.heartrate = [f numberFromString:heartRate];
NSLog(#"Log date is %#",[self.formController valueForField:#"date"]);
[f release];
NSError *error;
NSString *title;
NSString *growlDescription;
if ([self.log validateForInsert:&error]){
NSLog(#"after validation returned true");
if(![managedObjectContext save:&error]) {
NSLog(#"Unresolved error");
title = #"Error Occurred";
growlDescription = [error localizedDescription];
self.validationHasFailed = YES;
} else {
title = #"Log Saved!";
growlDescription = #"Log saved successfully";
[self.navigationController popViewControllerAnimated:YES];
}
} else {
NSLog(#"after validation returned false");
NSLog(#"Unresolved error");
title = #"Error Occurred";
growlDescription = [error localizedDescription];
self.validationHasFailed = YES;
}
IZGrowlNotification *notification = [[IZGrowlNotification alloc] initWithTitle:title
description:growlDescription
image:nil
context:nil
delegate:self];
[[IZGrowlManager sharedManager] postNotification:notification];
[notification release];
error = nil;
}

Answer 1

This is a bit late but I just saw your question so figured I'd toss an answer at you. Any object you add to the managed object context will be saved whenever you next save. You could leave your code as is and just delete the new object with [managedObjectContext deleteObject:self.log] but a better method is below.
Your code:
self.log = [NSEntityDescription insertNewObjectForEntityForName:#"Log" inManagedObjectContext:managedObjectContext];
Creates a new Log instance and inserts into the managed object context. What you want to do instead is:
self.log = [[Log alloc] initWithEntity:[NSEntityDescription entityForName:#"Log" inManagedObjectContext:managedObjectContext] insertIntoManagedObjectContext:nil];
This will create a new 'Log' instance that has not yet been inserted into the MOC. If validation succeeds, before you save the MOC you insert the self.log as follows:
[managedObjectContext insertObject:self.log];
Then you save. If validation fails, don't insert the object and you're good to go.