如果 json 值 == NULL，则 RESTKIT 内部映射失败

发布于 2024-12-06 12:04:25 字数 805 浏览 1 评论 0原文

我正在使用 RESTKIT 将服务器端的属性映射到客户端的属性。

当 RESTKIT 尝试将 NULL 值从服务器映射到客户端的 NSUInteger 属性时，我遇到了 [NSNull unsignedIntValue] 错误。

例如：

//User object property "new_questions_count" defined on client side with NSUInteger property
@interface User : NSObject <NSCoding>
{
    NSUInteger new_questions_count;
}

@property (nonatomic, assign) NSUInteger new_questions_count;

@end

//User Object Mapping - mapping "new_question_count" to server's json value
RKObjectMapping* userMapping = [RKObjectMapping mappingForClass:[User class]];
[userMapping mapAttributes:@"new_question_count",nil];
[provider setMapping:userMapping forKeyPath:@"user"];

对于上面的场景，如果 json 值为“new_questions_count”：null，我将遇到 [NSNull unsignedIntValue] 错误。

如何在客户端进行检查并解决此问题，而无需更改服务器端的实现？

原文

I am using RESTKIT to map the properties from the server side to the properties in the client side.

I am hitting the [NSNull unsignedIntValue] error when RESTKIT is trying to map a NULL value from the server to a NSUInteger property on the client side.

For example:

//User object property "new_questions_count" defined on client side with NSUInteger property
@interface User : NSObject <NSCoding>
{
    NSUInteger new_questions_count;
}

@property (nonatomic, assign) NSUInteger new_questions_count;

@end

//User Object Mapping - mapping "new_question_count" to server's json value
RKObjectMapping* userMapping = [RKObjectMapping mappingForClass:[User class]];
[userMapping mapAttributes:@"new_question_count",nil];
[provider setMapping:userMapping forKeyPath:@"user"];

For the above scenario, I will hit the [NSNull unsignedIntValue] error if the json value is "new_questions_count":null.

How can I do a check on the client side and resolve this without having to change the implementation on the server side?

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热血少△年 2024-12-13 12:04:25

尽管您没有显示实际解码 JSON 的代码，但我假设您使用的是正确遵循 NSNull 类的第三方库。在这种情况下，您可以使用以下命令检查键 @"x" 的对象是否为 null：

if ([[dictionary objectForKey:@"x"] isKindOfClass:[NSNull class]]) {
    // it is NULL
} else {
    // it is not NULL, but it still might
    // not be in the dictionary at all.
}

Although you have not showed the code where you actually decode the JSON, I am assuming that you are using a third party library that correctly respects the NSNull class. In this case, you can check if the object for key @"x" is null using this:

if ([[dictionary objectForKey:@"x"] isKindOfClass:[NSNull class]]) {
    // it is NULL
} else {
    // it is not NULL, but it still might
    // not be in the dictionary at all.
}

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