Json.NET自定义ValueProvider将对象转换为Guid
我正在尝试为Json.NET创建一个自定义ValueProvider,它将跳过序列化所有对象的过程,并将仅返回Guid类型的属性来表示其主键(作为参考)。
例:
jsonData: { myObject: {
id: "23e23-2gg5-6y666556-y6yg33",
property2: ""
}
}
应成为:
jsonData: { myObjectId: "23e23-2gg5-6y666556-y6yg33"
}
这是我到目前为止编写的代码。我非常接近使其工作,但是就我而言,CustomValueProvider
我似乎无法获取对象值。我怎样才能做到这一点?
private class CustomValueProvider : IValueProvider {
private readonly MemberInfo _member;
public CustomValueProvider(MemberInfo member)
{
_member = member;
}
public void SetValue(object target, object value)
{
throw new NotImplementedException();
}
public object GetValue(object target)
{
return // WHAT HERE??
}
}
private class CustomResolver : CamelCasePropertyNamesContractResolver
{
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var jsonProperty = base.CreateProperty(member, memberSerialization);
if (jsonProperty.PropertyType.IsClass && jsonProperty.PropertyType != typeof(string))
{
jsonProperty = new JsonProperty
{
PropertyName = member.Name.ToFirstCharLower() + "Id",
Readable = true,
ShouldSerialize = value => true,
PropertyType = typeof(Guid),
ValueProvider = new CustomValueProvider(member)
};
}
return jsonProperty;
}
}
private static readonly JsonSerializerSettings JsonSettings = new JsonSerializerSettings
{
ContractResolver = new CustomResolver(),
Formatting = Formatting.Indented
};
回答:
您希望将"Id"
值从嵌套对象内部提升到父对象。为此,您需要将两个价值提供者链接在一起:
- 一个外部值提供者,用于获取成员的值。
- 一个内部值提供程序,用于获取
Id
成员的值。
以下是这样做的:
class NestedValueProvider : IValueProvider{
readonly IValueProvider outerProvider;
readonly IValueProvider innerProvider;
public NestedValueProvider(IValueProvider outerProvider, IValueProvider innerProvider)
{
if (outerProvider == null || innerProvider == null)
throw new ArgumentNullException();
this.outerProvider = outerProvider;
this.innerProvider = innerProvider;
}
public void SetValue(object target, object value)
{
throw new NotImplementedException();
}
public object GetValue(object target)
{
var innerTarget = outerProvider.GetValue(target);
if (innerTarget == null)
return null;
return innerProvider.GetValue(innerTarget);
}
}
class CustomResolver : CamelCasePropertyNamesContractResolver
{
// Using an inner resolver prevents difficulties with recursion.
readonly CamelCasePropertyNamesContractResolver innerResolver = new CamelCasePropertyNamesContractResolver();
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var jsonProperty = base.CreateProperty(member, memberSerialization);
if (!jsonProperty.PropertyType.IsPrimitive && jsonProperty.PropertyType != typeof(string) && jsonProperty.Readable)
{
var innerContract = innerResolver.ResolveContract(jsonProperty.PropertyType);
if (innerContract is JsonObjectContract)
{
var objectContract = (JsonObjectContract)innerContract;
var idProperty = objectContract.Properties.GetClosestMatchProperty(ResolvePropertyName("Id"));
if (idProperty != null && idProperty.Readable && (innerResolver.ResolveContract(idProperty.PropertyType) is JsonPrimitiveContract))
{
jsonProperty = new JsonProperty
{
PropertyName = ResolvePropertyName(member.Name + "Id"),
Readable = true,
PropertyType = idProperty.PropertyType,
ValueProvider = new NestedValueProvider(jsonProperty.ValueProvider, idProperty.ValueProvider),
};
}
}
// Possibly handle innerContract is JsonArrayContract?
// Possibly handle innerContract is JsonDictionaryConract?
}
return jsonProperty;
}
}
注意使用内部合同解析器。这样可以防止递归调用递归类型时出现问题。
您可能还需要考虑处理具有ID的对象的集合或具有ID的对象的字典。例如在以下对象中,List<MyObject>
and
Dictionary<string, MyObject>
属性将公开以下内容MyObject
:
public class RootObject{
// Correctly not remapped
public string StringValue { get; set; }
// Correctly remaps to a GUID.
public MyObject MyObject { get; set; }
// Remap to a List<Guid> ?
public List<MyObject> MyObjectList { get; set; }
// Remap to a Dictionary<string, Guid> ?
public Dictionary<string, MyObject> MyObjectDictionary { get; set; }
}
public class MyObject
{
public Guid Id { get; set; }
public string Property2 { get; set; }
}
以上是 Json.NET自定义ValueProvider将对象转换为Guid 的全部内容, 来源链接: utcz.com/qa/408603.html