尝试使用RestKit上传图像时出现了一个奇怪的问题。我研究过类似的问题，但没有一个可以解决我的问题。
在我的应用程序中，用户可以在某些任务上创建评论。
所以我设置了RKEntityMapping和RKObjectMapping映射，如下所示：
- (RKEntityMapping *)commentsMapping {
RKEntityMapping *commentsMapping = [RKEntityMapping mappingForEntityForName:@"DBComments" inManagedObjectStore:objectManager.managedObjectStore];
commentsMapping.setDefaultValueForMissingAttributes = NO;
commentsMapping.identificationAttributes = @[@"id"];
[commentsMapping setModificationAttributeForName:@"updated_at"];
[commentsMapping addAttributeMappingsFromDictionary:@{
@"body" : @"body",
@"created_at" : @"created_at",
@"id" : @"id",
@"parent_id" : @"parent_id",
@"send_email" : @"send_email",
@"updated_at" : @"updated_at",
@"user.id" : @"user_id",
@"user.name" : @"user_name",
}];
[commentsMapping addRelationshipMappingWithSourceKeyPath:@"attachments" mapping:[self attachmentsMapping]];
return commentsMapping;
}
- (RKObjectMapping *)commentsRequestMapping {
RKObjectMapping *commentsRequestMapping = [RKObjectMapping requestMapping];
[commentsRequestMapping addAttributeMappingsFromDictionary:@{
@"body" : @"body",
@"created_at" : @"created_at",
@"id" : @"id",
@"parent_id" : @"parent_id",
@"send_email" : @"send_email",
@"updated_at" : @"updated_at",
@"user.id" : @"user_id",
@"user.name" : @"user_name",
}];
return commentsRequestMapping;
}
我已经定义了这样的URL_COMMENTS：
#define URL_COMMENTS @"/comments"
为了得到物品，我打电话给：
[[RKObjectManager sharedManager] getObjectsAtPath:URL_COMMENTS
parameters:@{@"item_id": parentID}
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
KLog(@"success");
}
failure:^(RKObjectRequestOperation *operation, NSError *error) {
KLog(@"fail");
}];
它运行正常，没有任何错误。
如果我需要创建新评论，请致电：
[[RKObjectManager sharedManager] postObject:comment path:URL_COMMENTS
parameters:nil
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
KLog(@"success");
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
KLog(@"fail");
}];
它也很完美，没有任何错误。
但是当我需要创建带有图片附件的评论时，我会打电话：
NSMutableURLRequest *request =[[RKObjectManager sharedManager] multipartFormRequestWithObject:comment
method:RKRequestMethodPOST
path:URL_COMMENTS
parameters:nil
constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
[formData appendPartWithFileData:UIImageJPEGRepresentation(image, 0.7)
name:@"photo"
fileName:@"photo.jpg"
mimeType:@"image/jpg"];
}];
RKObjectRequestOperation *operation = [[RKObjectManager sharedManager] objectRequestOperationWithRequest:request
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
// Success handler.
KLog(@"%@", [mappingResult firstObject]);
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
KLog(@"fail");
}];
[operation start];
现在问题是，在服务器端成功创建了注释，但应用程序因错误而终止：
Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<DBComments 0x11e01400> valueForUndefinedKey:]: the entity (null) is not key value coding-compliant for the key "id".'
这里还有一些Log
D restkit.object_mapping:RKMapperOperation.m:377 Executing mapping operation for representation: {
body = "Test attachment";
"created_at" = "2014-04-02T15:41:00+02:00";
id = 13379;
"parent_id" = 291160;
"updated_at" = "2014-04-02T15:41:00+02:00";
user = {
id = 12891;
name = "Rehmat Qadir";
};
}
and targetObject: (null)
D restkit.object_mapping:RKMapperOperation.m:300 Found mappable data at keyPath '': {
body = "Test attachment";
"created_at" = "2014-04-02T15:41:00+02:00";
id = 13379;
"parent_id" = 291160;
"updated_at" = "2014-04-02T15:41:00+02:00";
user = {
id = 12891;
name = "Rehmat Qadir";
};
}
CoreData: error: Failed to call designated initializer on NSManagedObject class 'DBComments'
2014-04-02 18:41:00.269 MeetingKing[14722:f03] D restkit.object_mapping:RKMapperOperation.m:231 Asked to map source object {
body = "Test attachment";
"created_at" = "2014-04-02T15:41:00+02:00";
id = 13379;
"parent_id" = 291160;
"updated_at" = "2014-04-02T15:41:00+02:00";
user = {
id = 12891;
name = "Rehmat Qadir";
};
} with mapping <RKEntityMapping:0xc686500 objectClass=DBComments propertyMappings=(
"<RKAttributeMapping: 0xc6877d0 user.id => user_id>",
"<RKAttributeMapping: 0xc6875c0 id => id>",
"<RKAttributeMapping: 0xc6875e0 send_email => send_email>",
"<RKAttributeMapping: 0xc687610 created_at => created_at>",
"<RKAttributeMapping: 0xc687630 parent_id => parent_id>",
"<RKAttributeMapping: 0xc6877e0 updated_at => updated_at>",
"<RKAttributeMapping: 0xc687850 user.name => user_name>",
"<RKAttributeMapping: 0xc687920 body => body>",
"<RKRelationshipMapping: 0xc688b90 attachments => attachments>"
)>
D restkit.object_mapping:RKMappingOperation.m:952 Starting mapping operation...
*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<DBComments 0x11e01400> valueForUndefinedKey:]: the entity (null) is not key value coding-compliant for the key "id".'
我认为这可能与某些URL问题有关。
我发送的请求位于URL_COMMENTS，定义为#define URL_COMMENTS @"/comments"
我已尝试在comments发送请求（没有开始/）并将pathPattern中的responseDescriptor设置为/comments（以/开头）
我也尝试过发送请求/comments（包含开头/），并将pathPattern中的responseDescriptor设为comments（不开始/）
[RKResponseDescriptor responseDescriptorWithMapping:[self commentsMapping]
method:RKRequestMethodGET
pathPattern:URL_COMMENTS
keyPath:@"" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)],
还尝试将两个地方设置为相同或不同/，但没有任何效果。
我之前需要调用/方法时，我已经通过路径AFNetworking的某种组合修复了此错误。但不知道为什么会出现这种错误。
请帮忙
答案 0 :(得分：8)
因为注释是一个托管对象，并且您要求RestKit将其视为普通对象。因此，RestKit正在尝试创建一个新实例，在该实例中设置响应数据并在创建时失败。
您应该使用managedObjectRequestOperationWithRequest:managedObjectContext:success:failure:来创建操作，以便它具有对MOC的引用，并且可以正确地创建实体实例（尽管在这种情况下它应该找到现有的实体实例）。