RestKit 0.20：映射复杂的动态嵌套 JSON
Posted
技术标签:
【中文标题】RestKit 0.20：映射复杂的动态嵌套 JSON【英文标题】：RestKit 0.20: mapping complex dynamic nested JSON 【发布时间】：2014-04-17 17:22:47 【问题描述】：我对 ios 开发和 RestKit 框架（使用 0.20.3 版）非常熟悉。单实体映射就像一个魅力。然而，当谈到动态嵌套 JSON 的关系映射时，过去几天我一直在苦苦挣扎。我有以下我正在尝试映射的 JSON 响应：
"chargerstations": [
"csmd":
"id": 1190,
"name": "Tammasaarenkatu 7",
"Street": "Tammasaarenkatu",
"House_number": "7",
"Zipcode": "00180",
"City": "Ruoholahti",
"Municipality_ID": "091",
"Municipality": "Helsinki",
"County_ID": "01",
"County": "Uusimaa",
"Description_of_location": "",
"Owned_by": "Helen",
"Number_charging_points": 1,
"Position": "(60.16172,24.90679)",
"Image": "Kommer",
"Available_charging_points": 1,
"User_comment": "",
"Contact_info": "",
"Created": "2012-03-30 11:40:48",
"Updated": "2013-04-16 11:52:47",
"Station_status": 1,
"Land_code": "FIN",
"International_id": "FIN_01190"
,
"attr":
"st":
"2":
"attrtypeid": "2",
"attrname": "Availability",
"attrvalid": "1",
"trans": "Public",
"attrval": ""
,
"3":
"attrtypeid": "3",
"attrname": "Location",
"attrvalid": "1",
"trans": "Street",
"attrval": ""
,
"6":
"attrtypeid": "6",
"attrname": "Time limit",
"attrvalid": "2",
"trans": "No",
"attrval": ""
,
"7":
"attrtypeid": "7",
"attrname": "Parking fee",
"attrvalid": "2",
"trans": "No",
"attrval": false
,
"21":
"attrtypeid": "21",
"attrname": "Real-time information",
"attrvalid": "2",
"trans": "No",
"attrval": ""
,
"22":
"attrtypeid": "22",
"attrname": "Public funding",
"attrvalid": "4",
"trans": "None",
"attrval": ""
,
"24":
"attrtypeid": "24",
"attrname": "Open 24h",
"attrvalid": "1",
"trans": "Yes",
"attrval": "1"
,
"conn":
"1":
"1":
"attrtypeid": "1",
"attrname": "Accessibility",
"attrvalid": "6",
"trans": "Cellular phone",
"attrval": ""
,
"4":
"attrtypeid": "4",
"attrname": "Connector",
"attrvalid": "32",
"trans": "Mennekes-type 2 (IEC 62196-2) \n",
"attrval": ""
,
"5":
"attrtypeid": "5",
"attrname": "Charging capacity",
"attrvalid": "11",
"trans": "400V 3-phase max 32A",
"attrval": ""
,
"17":
"attrtypeid": "17",
"attrname": "Vehicle type",
"attrvalid": "1",
"trans": "All vehicles",
"attrval": ""
,
"18":
"attrtypeid": "18",
"attrname": "Reservable",
"attrvalid": "2",
"trans": "No",
"attrval": ""
,
"20":
"attrtypeid": "20",
"attrname": "Charge mode",
"attrvalid": "3",
"trans": "Mode 3",
"attrval": ""
,
"25":
"attrtypeid": "25",
"attrname": "Fixed cable",
"attrvalid": "2",
"trans": "No",
"attrval": ""
"2":
"1": same structure as above
"<conn no. x>":
"1": same structure as above
]
我创建了一个包含 2 个实体的核心数据模型； “ChargingStation”包含来自“csmd”和“attr.st”字典的数据，“Connector”包含来自 JSON 的动态嵌套部分 (attr.conn) 的数据。一个充电站可能有多个连接器，但一个连接器可能只属于一个充电站。因此，我定义了一个从“ChargingStation”到“Connector”的多对多关系，与“Connector”实体的反向一对一关系。
http://imgur.com/Q0mhlIi
我的模型是使用 mogenerator 生成的。这是我目前关于映射本身的代码（在 AppDelegate.m 中）：
RKEntityMapping *chargingStationMapping = [RKEntityMapping mappingForEntityForName:@"ChargingStation"
inManagedObjectStore:managedObjectStore];
[chargingStationMapping addAttributeMappingsFromDictionary:@
@"attr.st.2.trans" : @"availabilityType",
@"csmd.City" : @"city",
@"csmd.Position" : @"coordinates",
@"csmd.House_number" : @"houseNumber",
@"csmd.id" : @"stationID",
@"csmd.International_id" : @"internationalID",
@"csmd.Description_of_location" : @"locationDescription",
@"csmd.Image" : @"locationImage",
@"attr.st.3.trans" : @"locationName",
@"csmd.name" : @"name",
@"csmd.Available_charging_points" : @"numChargingPoints",
@"attr.st.24.trans" : @"openingHours",
@"attr.st.7.trans" : @"parkingFee",
@"attr.st.22.trans" : @"publicFunding",
@"attr.st.21.trans" : @"realtimeInfo",
@"csmd.Street" : @"street",
@"attr.st.6.trans" : @"timeLimit",
@"csmd.Zipcode" : @"zipCode"
];
chargingStationMapping.identificationAttributes = @[@"stationID"];
RKDynamicMapping *dynamicConnectorMapping = [[RKDynamicMapping alloc] init];
[dynamicConnectorMapping setObjectMappingForRepresentationBlock:^RKObjectMapping *(id representation)
RKEntityMapping *connectorMapping = [RKEntityMapping mappingForEntityForName:@"Connector"
inManagedObjectStore:managedObjectStore];
NSDictionary *connectors = [representation valueForKeyPath:@"attr.conn"];
for (NSString *attr in connectors)
NSDictionary *connector = [connectors objectForKey:attr];
[connector enumerateKeysAndObjectsUsingBlock: ^(id key, id obj, BOOL *stop)
NSLog(@"Attr from outer connector object: %@", attr);
if ([key isEqualToString:@"1"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"accessibility"
];
else if ([key isEqualToString:@"4"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"connector"
];
else if ([key isEqualToString:@"5"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"chargingCapacity"
];
else if ([key isEqualToString:@"17"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"vehicleType"
];
else if ([key isEqualToString:@"18"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"reservable"
];
else if ([key isEqualToString:@"20"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"chargeMode"
];
else if ([key isEqualToString:@"23"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"manufacturer"
];
else if ([key isEqualToString:@"25"])
[chargingStationMapping addAttributeMappingsFromDictionary:@
[NSString stringWithFormat:@"attr.conn.%@.%@.trans", attr, key]: @"fixedCable"
];
];
connectorMapping.identificationAttributes = @[@"id"];
[connectorMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"ChargingStation"
toKeyPath:@"chargingstation"
withMapping:chargingStationMapping]];
return connectorMapping;
];
RKResponseDescriptor *connectorDescription = [RKResponseDescriptor responseDescriptorWithMapping:dynamicConnectorMapping method:RKRequestMethodGET pathPattern:nil keyPath:@"chargerstations" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
RKResponseDescriptor *chargingStationDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:chargingStationMapping method:RKRequestMethodAny pathPattern:nil keyPath:@"chargerstations.attr.conn" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:chargingStationDescriptor];
[objectManager addResponseDescriptor:connectorDescription];
[objectManager getObjectsAtPath:<URL_request>"
parameters:nil
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult)
ChargingStation *cstation = [mappingResult firstObject];
NSLog(@"House number: %@", cstation.houseNumber);
failure:^(RKObjectRequestOperation *operation, NSError *error) ];
当我尝试运行它时，我收到以下错误消息：
Assertion failure in -[RKEntityMapping addPropertyMapping:], /<my_project_directory>/Pods/RestKit/Code/ObjectMapping/RKObjectMapping.m:237
2014-04-21 18:30:55.200 ChargeIt[844:530b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Unable to add mapping for keyPath connector, one already exists...'
我认为这是因为我有两个 ResponseDescriptor 用于同一个父 keyPath，即“充电站”？我已经阅读了https://github.com/RestKit/RestKit/wiki/Object-mapping 的映射指南并查看了其他一些教程，以及关于 SO 的其他问题，但我仍然无法终生弄清楚我做错了什么。
如果我能得到任何帮助和/或推动正确的方向，我将不胜感激。
更新：我现在已经按照@Wain 建议的方法添加了修改后的代码，并且还升级到了Restkit 的0.23.1 版本。映射现在可以工作了（好吧，至少它完成了映射而没有任何错误:)...）。但是，当我尝试访问与充电站关联的连接器时，它返回一个空的 NSSet，并且在尝试记录 NSSet 时，我在日志中收到以下错误：
connectors = "<relationship fault: 0x9fb5fe0 'connectors'>";
我还查看了 SQLite 数据库，我注意到连接器实体在其表中获得了“ChargingStation”字段，但 ChargingStation 实体在其表中没有任何“连接器”字段。
RKEntityMapping *chargingStationMapping = [RKEntityMapping mappingForEntityForName:@"ChargingStation"
inManagedObjectStore:managedObjectStore];
[chargingStationMapping addAttributeMappingsFromDictionary:@
@"attr.st.2.trans" : @"availabilityType",
@"chargerstations.csmd.City" : @"city",
@"csmd.Position" : @"coordinates",
@"csmd.House_number" : @"houseNumber",
@"csmd.id" : @"stationID",
@"csmd.International_id" : @"internationalID",
@"csmd.Description_of_location" : @"locationDescription",
@"csmd.Image" : @"locationImage",
@"attr.st.3.trans" : @"locationName",
@"csmd.name" : @"name",
@"csmd.Available_charging_points" : @"numChargingPoints",
@"attr.st.24.trans" : @"openingHours",
@"attr.st.7.trans" : @"parkingFee",
@"attr.st.22.trans" : @"publicFunding",
@"attr.st.21.trans" : @"realtimeInfo",
@"csmd.Street" : @"street",
@"attr.st.6.trans" : @"timeLimit",
@"csmd.Zipcode" : @"zipCode"
];
chargingStationMapping.identificationAttributes = @[@"stationID"];
RKEntityMapping *connectorMapping = [RKEntityMapping mappingForEntityForName:@"Connector"
inManagedObjectStore:managedObjectStore];
connectorMapping.forceCollectionMapping = YES;
[connectorMapping addAttributeMappingFromKeyOfRepresentationToAttribute:@"connectorID"];
[connectorMapping addAttributeMappingsFromDictionary:@
@"(connectorID).1.trans": @"accessibility",
@"(connectorID).4.trans": @"connector",
@"(connectorID).5.trans": @"chargingCapacity",
@"(connectorID).17.trans": @"vehicleType",
@"(connectorID).18.trans": @"reservable",
@"(connectorID).20.trans": @"chargeMode",
@"(connectorID).23.trans": @"manufacturer",
@"(connectorID).25.trans": @"fixedCable"
];
[chargingStationMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"attr.conn"
toKeyPath:@"connectors"
withMapping:connectorMapping]];
RKResponseDescriptor *chargingStationDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:chargingStationMapping
method:RKRequestMethodAny
pathPattern:nil
keyPath:@"chargerstations"
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:chargingStationDescriptor];
[objectManager getObjectsAtPath:@"datadump.php?apikey=<API_KEY>&file=false&format=json&countrycode=FIN"
parameters:nil
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult)
ChargingStation *cstation = [mappingResult firstObject];
NSLog(@"Connectors: %@", cstation);
NSLog(@"Connector info: %i", cstation.connectorsSet.count);
failure:^(RKObjectRequestOperation *operation, NSError *error) ];
从我在日志中看到的内容来看，它正确地映射了所有内容（请参阅日志输出中相当长的附加部分）。有什么想法吗？
to object <ChargingStation: 0x9c84cf0> (entity: ChargingStation; id: 0x151c4f00 <x-coredata://77C8299D-FDDB-4810-8D22-C13538858DA1/ChargingStation/p18> ; data:
availabilityType = Public;
city = nil;
connectors = "<relationship fault: 0x9c84270 'connectors'>";
coordinates = "(60.16172,24.90679)";
houseNumber = 7;
internationalID = "FIN_01190";
locationDescription = "";
locationImage = Kommer;
locationName = Street;
name = "Tammasaarenkatu 7";
numChargingPoints = 1;
openingHours = Yes;
parkingFee = No;
paymentMethods = nil;
publicFunding = None;
realtimeInfo = No;
stationID = 1190;
street = Tammasaarenkatu;
timeLimit = No;
zipCode = 00180;
) with object mapping (null)
2014-04-30 19:35:06.949 ChargeIt[6131:5613] D restkit.object_mapping:RKMappingOperation.m:766 Collection mapping forced for NSDictionary, mapping each key/value independently...
2014-04-30 19:35:06.950 ChargeIt[6131:5613] D restkit.object_mapping:RKMappingOperation.m:640 Mapping one to many relationship value at keyPath 'attr.conn' to 'connectors'
2014-04-30 19:35:06.951 ChargeIt[6131:3d13] D restkit.object_mapping:RKPropertyInspector.m:131 Cached property inspection for Class 'Connector':
accessibility =
isPrimitive = 0;
keyValueCodingClass = NSString;
name = accessibility;
;
...
;
vehicleType =
isPrimitive = 0;
keyValueCodingClass = NSString;
name = vehicleType;
;
2014-04-30 19:35:06.984 ChargeIt[6131:5613] I restkit.core_data:RKInMemoryManagedObjectCache.m:94 Caching instances of Entity 'Connector' by attributes 'connectorID'
2014-04-30 19:35:07.042 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:541 Performing nested object mapping using mapping <RKRelationshipMapping: 0x9e4ce70 attr.conn => connectors> for data:
1 =
1 =
attrname = Accessibility;
attrtypeid = 1;
attrval = "";
attrvalid = 6;
trans = "Cellular phone";
;
17 =
attrname = "Vehicle type";
attrtypeid = 17;
attrval = "";
attrvalid = 1;
trans = "All vehicles";
;
18 =
attrname = Reservable;
attrtypeid = 18;
attrval = "";
attrvalid = 2;
trans = No;
;
20 =
attrname = "Charge mode";
attrtypeid = 20;
attrval = "";
attrvalid = 3;
trans = "Mode 3";
;
25 =
attrname = "Fixed cable";
attrtypeid = 25;
attrval = "";
attrvalid = 2;
trans = No;
;
4 =
attrname = Connector;
attrtypeid = 4;
attrval = "";
attrvalid = 32;
trans = "Mennekes-type 2 (IEC 62196-2) \n";
;
5 =
attrname = "Charging capacity";
attrtypeid = 5;
attrval = "";
attrvalid = 11;
trans = "400V 3-phase max 32A";
;
;
2014-04-30 19:35:07.043 ChargeIt[6131:5613] D restkit.object_mapping:RKMappingOperation.m:859 Starting mapping operation...
2014-04-30 19:35:07.044 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:860 Performing mapping operation: <RKMappingOperation 0x9cdcdd0> for 'Connector' object. Mapping values from object
1 =
1 =
attrname = Accessibility;
attrtypeid = 1;
attrval = "";
attrvalid = 6;
trans = "Cellular phone";
;
17 =
attrname = "Vehicle type";
attrtypeid = 17;
attrval = "";
attrvalid = 1;
trans = "All vehicles";
;
18 =
attrname = Reservable;
attrtypeid = 18;
attrval = "";
attrvalid = 2;
trans = No;
;
20 =
attrname = "Charge mode";
attrtypeid = 20;
attrval = "";
attrvalid = 3;
trans = "Mode 3";
;
25 =
attrname = "Fixed cable";
attrtypeid = 25;
attrval = "";
attrvalid = 2;
trans = No;
;
4 =
attrname = Connector;
attrtypeid = 4;
attrval = "";
attrvalid = 32;
trans = "Mennekes-type 2 (IEC 62196-2) \n";
;
5 =
attrname = "Charging capacity";
attrtypeid = 5;
attrval = "";
attrvalid = 11;
trans = "400V 3-phase max 32A";
;
;
to object <Connector: 0x1965b460> (entity: Connector; id: 0x9e0a940 <x-coredata://77C8299D-FDDB-4810-8D22-C13538858DA1/Connector/p35> ; data:
accessibility = Other;
chargeMode = "Mode 3";
chargingCapacity = "400V 3-phase max 32A";
chargingstation = "0x9c3f620 <x-coredata://77C8299D-FDDB-4810-8D22-C13538858DA1/ChargingStation/p35>";
connector = "Type 2 + Schuko CEE 7/4";
connectorID = 1;
fixedCable = No;
manufacturer = Manufacturer;
reservable = No;
vehicleType = "All vehicles";
) with object mapping (null)
2014-04-30 19:35:07.047 ChargeIt[6131:5613] D restkit.object_mapping:RKMappingOperation.m:821 Found nested mapping definition to attribute 'connectorID'
2014-04-30 19:35:07.048 ChargeIt[6131:5613] D restkit.object_mapping:RKMappingOperation.m:824 Found nesting value of '1' for attribute 'connectorID'
2014-04-30 19:35:07.048 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:438 Found transformable value at keyPath '<RK_NESTING_ATTRIBUTE>'. Transforming from class '__NSCFString' to 'NSNumber'
2014-04-30 19:35:07.048 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:453 Mapping attribute value keyPath '<RK_NESTING_ATTRIBUTE>' to 'connectorID'
2014-04-30 19:35:07.049 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:484 Skipped mapping of attribute value from keyPath '<RK_NESTING_ATTRIBUTE> to keyPath 'connectorID' -- value is unchanged (1)
2014-04-30 19:35:07.049 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:507 Skipping attribute mapping for special keyPath '<RK_NESTING_ATTRIBUTE>'
2014-04-30 19:35:07.050 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:438 Found transformable value at keyPath '1.4.trans'. Transforming from class '__NSCFString' to 'NSString'
2014-04-30 19:35:07.064 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:453 Mapping attribute value keyPath '1.4.trans' to 'connector'
....
2014-04-30 19:35:07.118 ChargeIt[6131:5613] T restkit.object_mapping:RKMappingOperation.m:622 Mapped `NSSet` relationship object from keyPath 'attr.conn' to 'connectors'. Value: (
<Connector: 0x1965b460> (entity: Connector; id: 0x9e0a940 <x-coredata://77C8299D-FDDB-4810-8D22-C13538858DA1/Connector/p35> ; data:
accessibility = "Cellular phone";
chargeMode = "Mode 3";
chargingCapacity = "400V 3-phase max 32A";
chargingstation = "0x9c3f620 <x-coredata://77C8299D-FDDB-4810-8D22-C13538858DA1/ChargingStation/p35>";
connector = "Mennekes-type 2 (IEC 62196-2) \n";
connectorID = 1;
fixedCable = No;
manufacturer = Manufacturer;
reservable = No;
vehicleType = "All vehicles";
)
)
【问题讨论】：
您应该首先升级到版本 0.23.1（或至少 0.22.0）。 【参考方案1】：如果可以的话，你真的应该改变 JSON，它不是很好。
问题在于动态映射中的循环，您在该循环中分析传入数据，然后尝试将大量映射添加到同一键路径。您需要采用不同的方法，以便拥有一个关系，该关系使用该关系处理所有连接器（链接到另一个映射）。
看看使用addAttributeMappingFromKeyOfRepresentationToAttribute:。第一个映射具有到第二个映射的relationship 并指定源。密钥路径attr.conn。第二个映射使用表示键来处理未知键。
【讨论】：
已升级到版本 0.23.1，但在尝试设置以下内容时出现错误：objectManager.managedObjectStore = managedObjectStore ...显然，在 RKObjectManager 对象类型上找不到属性 managedObjectStore。无论如何，关于 JSON - 我可以:)。至于你的建议，我真的没有这么想过。非常感谢您的意见！我一定会尝试你的方法，并在我得到它后发布一个工作示例。 在上面添加了更新的代码。非常感谢到目前为止的帮助 - 它让我顺利完成了映射。不过，我遇到了另一个问题，我还没有弄清楚（请参阅更新的问题）。关于 managedStore 的错误；我只是忘记将#importconnectors = "<relationship fault: 0x9fb5fe0 'connectors'>"; 只是表示关系数据没有加载到内存中，这不是错误，并且关系可以填充或为空（但如果不加载它就无法判断）。您是否尝试过访问关系中的项目，而不仅仅是记录关系？
我尝试了以下方法（使用 fetchRequest）：for(ChargingStation *cstation in fetchedObjects) NSLog(@"Connectors for %@: %@", cstation.name,[cstation.connectors allObjects]); for(Connector *connector in [cstation connectors]) NSLog(@"Manufacturer %@", connector.manufacturer); 尝试访问“制造商”属性会产生错误：“无法在对象连接器的前向类中找到”。此外，我的映射没有完全按预期工作。有许多 ChargingStation 对象没有任何连接器。还在调试中
通过设置[RKEntityMapping setEntityIdentificationInferenceEnabled:NO]解决并移除了连接器映射的标识属性。这种方式总是为连接器对象创建新实例。 @Wain：非常感谢您的所有帮助和输入，为我指明了正确的方向！没有你就无法解决这个问题。以上是关于RestKit 0.20：映射复杂的动态嵌套 JSON的主要内容，如果未能解决你的问题，请参考以下文章
RestKit 0.20：在 JSON 中使用动态扁平化层次结构