RestKit – fetchFromDataStore（caching）问题

我正在查看RestKit框架以及它如何工作。 然后我创build一个简单的项目，将调用Github api，并将数据加载到一个tableview中 – 在我读过一些教程后 – 关于从远程加载和映射它工作正常，并加载到tableview，但是当我试图从数据存储 – 离线模式 – 应用程序将崩溃，这是日志：

2012-07-29 16:21:41.611 RKGithubClient_FromZtoH[29181:c07] I restkit:RKLog.m:33 RestKit initialized... 2012-07-29 16:21:53.161 RKGithubClient_FromZtoH[29181:c07] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'executeFetchRequest:error: A fetch request must have an entity.' *** First throw call stack: (0x20b9022 0x197acd6 0xf15871 0x643c 0x42e5 0x3e14 0x4697 0x53838f 0x5385eb 0x5394ed 0x4a6a0c 0x4abf92 0x4a614b 0x495550 0x495670 0x495836 0x49c72a 0x2a6a 0x46d386 0x46e274 0x47d183 0x47dc38 0x471634 0x25e1ef5 0x208d195 0x1ff1ff2 0x1ff08da 0x1fefd84 0x1fefc9b 0x46dc65 0x46f626 0x259d 0x2505) terminate called throwing an exception 

这是fetchFromDataStore方法：

 - (void)fetchFromDataStore { NSFetchRequest *request = [[[RKObjectManager sharedManager] mappingProvider] fetchRequestForResourcePath:self.resourcePath]; //self resourcePath]]; self.repos = [GithubRepo objectsWithFetchRequest:request]; [self.tableView reloadData]; } 

任何想法为什么这是因为我已经为他们创build了实体，你可以从这个链接检查源代码：

源代码

另外，有没有用于RestKitcaching的有用的例子或教程？

谢谢，

Answer 1

最后，我得到了答案。

问题是，当我要求：NSFetchRequest * request = [[[RKObjectManager sharedManager] mappingProvider] fetchRequestForResourcePath：self.resourcePath]; 在myViewController.m，返回空。 发生的原因是因为对象映射器没有被configuration为正确处理核心数据caching。 我在用着：

 - (void)setObjectMapping:(RKObjectMappingDefinition *)objectMapping forResourcePathPattern:(NSString *)resourcePathPattern; 

而我应该使用：

 - (void)setObjectMapping:(RKObjectMappingDefinition *)objectMapping forResourcePathPattern:(NSString *)resourcePathPattern withFetchRequestBlock:(RKObjectMappingProviderFetchRequestBlock)fetchRequestBlock; 

它位于对象映射的Core数据扩展中。 您提供的额外块用于根据resourcePath（在本例中为用户RestKit）中传递的参数来决定需要哪个获取请求。 在具体的情况下，我想要返回一个取回请求，当回购的用户==“RestKit”时寻找回购。

尽pipe这个方法很难find，但是这个文档非常有用：

 /** Configures an object mapping to be used when during a load event where the resourcePath of the RKObjectLoader instance matches resourcePathPattern. The resourcePathPattern is a SOCKit pattern matching property names preceded by colons within a path. For example, if a collection of reviews for a product were loaded from a remote system at the resourcePath @"/products/1234/reviews", object mapping could be configured to handle this request with a resourcePathPattern of @"/products/:productID/reviews". **NOTE** that care must be taken when configuring patterns within the provider. The patterns will be evaluated in the order they are added to the provider, so more specific patterns must precede more general patterns where either would generate a match. @param objectMapping The object mapping to use when the resourcePath matches the specified resourcePathPattern. @param resourcePathPattern A pattern to be evaluated using an RKPathMatcher against a resourcePath to determine if objectMapping is the appropriate mapping. @param fetchRequestBlock A block that accepts an individual resourcePath and returns an NSFetchRequest that should be used to fetch the local objects associated with resourcePath from CoreData, for use in properly processing local deletes @see RKPathMatcher @see RKURL @see RKObjectLoader */ - (void)setObjectMapping:(RKObjectMappingDefinition *)objectMapping forResourcePathPattern:(NSString *)resourcePathPattern withFetchRequestBlock:(RKObjectMappingProviderFetchRequestBlock)fetchRequestBlock;