countForFetchRequest返回1为空表 [英] countForFetchRequest returning 1 for empty table

问题描述

我正在执行一个'countForFetchRequest'，它总是返回比我的表中的记录数多1个。

  NSFetchRequest * request = [[NSFetchRequest alloc] init]; 
 [request setEntity：[NSEntityDescription entityForName：@TESTDATAinManagedObjectContext：self.managedObjectContext]]; 
 
 NSError * error = nil; 
 NSUInteger count = [self.managedObjectContext countForFetchRequest：request error：& error]; 
 if（count == NSNotFound）{
 //处理错误
} 
 
 return count; 
  

当我的表为空时返回1。如果我的表有3行，则返回4。

  sqlite>从ZTESTDATA中选择计数（*）; 
 0 
 sqlite>关于我在做什么的任何想法？
 $ p 
 
 
 
 
 >正如其他人建议的那样，请执行获取而不是计数，并打印出Core Data找到的内容，您会找到您的答案。
 
I am executing a 'countForFetchRequest' and it is always returning 1 more count than the number of records in my table.
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:@"TESTDATA" inManagedObjectContext:self.managedObjectContext]];

NSError *error = nil;
NSUInteger count = [self.managedObjectContext countForFetchRequest:request error:&error];
if(count == NSNotFound) {
    // Handle error
}

return count;
That returns 1 when my table is empty.  Returns 4 if my table has 3 rows.
sqlite> select count(*) from ZTESTDATA;
0
sqlite> 
Any ideas on what I am doing wrong?
解决方案
Count is always accurate but it counts both what is in memory (not saved yet) and what is on disk.

As others have suggested, do a fetch instead of a count and print out what Core Data finds and you will find your answer.

                        
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