在运行时性能的Web API序列化条件 [英] Web API Conditional Serialization of properties at runtime
问题描述
我期待在建设ASP.Net使用的WebAPI的API。
I am looking at building an API using WebAPI in ASP.Net.
我有一个要求，基于在 运行，而不是编译时的一些自定义逻辑有条件地排除在XML或JSON属性。
I have a requirement to conditionally exclude properties from the XML or JSON based on some custom logic at RunTime and not Compile Time.
我不得不删除从响应的XML或JSON，它是没有好只是包括空或空值的变量。
I have to remove the xml or json from the response, it is no good just including the tags with a null or empty value.
我已经试过各种方法，但没有去上班。
I have tried various approaches, none of which I seem to be able to get to work.
我曾尝试以下
委托处理程序 from这里
public class ResponseDataFilterHandler : DelegatingHandler
{
protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
return base.SendAsync(request, cancellationToken)
.ContinueWith(task =>
{
var response = task.Result;
//Manipulate content here
var content = response.Content as ObjectContent;
if (content != null && content.Value != null)
{
}
//Or replace the content
//response.Content = new ObjectContent(typeof(object), new object(), new MyFormatter());
return response;
});
}
}
当然，我可以在这里空的属性，但他们仍然会出现在响应。
Sure I can null properties out here, but they still appear in the response.
DataContractSurrogate 相似这个
public class MySurrogate: IDataContractSurrogate
{
public object GetCustomDataToExport(Type clrType, Type dataContractType)
{
return null;
}
public object GetCustomDataToExport(System.Reflection.MemberInfo memberInfo, Type dataContractType)
{
return null;
}
public Type GetDataContractType(Type type)
{
return null;
}
public object GetDeserializedObject(object obj, Type targetType)
{
return null;
}
public void GetKnownCustomDataTypes(System.Collections.ObjectModel.Collection<Type> customDataTypes)
{
}
public object GetObjectToSerialize(object obj, Type targetType)
{
if (obj == null) return null;
var type = obj.GetType();
type.GetProperties().ToList()
.ForEach(prop =>
{
try
{
var attr = prop.GetCustomAttributes(typeof(ConditionalDataMemberAttribute), false);
if (attr.Any())
{
var proptype = prop.PropertyType;
//Set the property value to its default value
prop.GetSetMethod().Invoke(obj,
new[] { proptype.IsValueType ? Activator.CreateInstance(proptype) : null });
}
}
catch { }
});
return obj;
}
public Type GetReferencedTypeOnImport(string typeName, string typeNamespace, object customData)
{
return null;
}
public System.CodeDom.CodeTypeDeclaration ProcessImportedType(System.CodeDom.CodeTypeDeclaration typeDeclaration, System.CodeDom.CodeCompileUnit compileUnit)
{
return null;
}
}
同样，我可以只空的属性了，我不能删除从输出的XML或JSON。
Again, I can just null the properties out, I cannot remove the xml or json from the output.
我有一个想法，我可以动态编译特定类与所需的属性然后使用DataContractSurrogate与我的新的动态编译的类的实例换出原来的实例 - 但我不喜欢它。
I have an idea where I can dynamically compile a specific class with the required attributes then use the DataContractSurrogate to swap out the original instance with an instance of my new dynamic compiled class - but I don't like it.
香港专业教育学院试图寻找的DataContractSerializer ，但它是密封的，所以我不能从中获得 - 我也看了反编译，并作出一些改变，但它再次使用了内部类如 DataContract - 我觉得我需要挂接到序列化，但我不知道如何
Ive tried looking at DataContractSerializer but it is sealed so I cant derive from it - i've also looked to decompile it and make some changes but again it uses internal classes such as DataContract - I feel I need to hook into the serialization but I don't know how to ?
推荐答案
好吧，我成功地做到这一点使用了一点什么，我已经做了，再加上一些在这里的建议，我也偶然发现的这个
Okay I managed to do this using a bit of what I had already done, plus some of the suggestions on here, I also stumbled upon this
首先，我们通过增加一个 DelegatingHandler 进入管道开始。
First we start by adding a DelegatingHandler into the pipeline.
config.MessageHandlers.Add(new ResponseDataFilterHandler());
和类本身
public class ResponseDataFilterHandler : DelegatingHandler
{
protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
return base.SendAsync(request, cancellationToken)
.ContinueWith(task =>
{
var response = task.Result;
var content = response.Content as ObjectContent;
if (content != null && content.Value != null)
{
var isJson = response.RequestMessage.GetQueryNameValuePairs().Any(r => r.Key == "json" && r.Value == "true");
response.Content = new StringContent(Helper.GetResponseData(content.Value, isJson));
}
return response;
});
}
}
然后我们有一个辅助类的方法获取新的序列化的字符串（这不是督促code; P）
Then we have a helper class method to get the new serialized string (this is not prod code ;p)
public static class Helper
{
public static string GetResponseData(object root,bool isJson)
{
string json = JsonConvert.SerializeObject(root, new JsonSerializerSettings { ContractResolver = new ShouldSerializeContractResolver()});
if (!isJson)
{
XmlDocument doc = JsonConvert.DeserializeXmlNode(json,"response");
json = doc.OuterXml;
}
return json;
}
}
和最后的 ContractReoslver
public class ShouldSerializeContractResolver : DefaultContractResolver
{
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
JsonProperty property = base.CreateProperty(member, memberSerialization);
property.ShouldSerialize = (i) =>
{
//Your logic goes here
var r = !property.PropertyName.StartsWith("block-ref");
return r;
};
return property;
}
}
这一切的根源，通过JSON和皈依为xml如果需要的话，我的测试项目中，我使用一个查询字符串（JSON = TRUE）来指定，如果格式应JSON而不是XML。
this roots everything through Json and the converts to xml if required, for my test project I am using a querystring (json=true) to specify if the format should be json instead of xml.
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