核心数据库是空测试 [英] core data database is empty test

问题描述

如何测试核心数据库是否为空？
我试过：

How can I test if the core data database is empty? I tried:

NSIndexPath *path1 = [NSIndexPath indexPathForRow:0 inSection:0];
NSManagedObject *managedObject = [self.fetchedResultsController objectAtIndexPath:path1];
if([[managedObject valueForKey:@"date"] description]!=nil){SOMEFUNCTION}else{SOMEFUNCTION}

感谢

推荐答案

您必须为核心资料中使用的每个实体建立撷取要求。如果fetchrequest返回没有结果，您没有此实体的对象存储在您的核心数据中。

you have to create a fetchrequest for each entity you use in core data. if the fetchrequest returns without results you don't have objects of this entity stored in your core data.

- (BOOL)coreDataHasEntriesForEntityName:(NSString *)entityName {
    NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:self.managedObjectContext];
    [request setEntity:entity];
    [request setFetchLimit:1];
    NSError *error = nil;
    NSArray *results = [self.managedObjectContext executeFetchRequest:request error:&error];
    if (!results) {
        LogError(@"Fetch error: %@", error);
        abort();
    }
    if ([results count] == 0) {
        return NO;
    }
    return YES;
}

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