通过反射进行动态json序列化过滤 [英] Dynamic json serialization filtering via reflection
问题描述
我想为json.net创建一个动态合同解析器,它将在运行时中排除字段.这个想法是传递给构造器 something ,该构造器将排除CreateProperties覆盖内的某些字段.
I want to create a dynamic contract resolver for json.net which will exclude fields in runtime. The idea is to pass into constructor something which will exclude certain fields inside CreateProperties override.
到目前为止,我想出了传递PropertyInfo[]
的方法,该方法依赖于Json/Class属性名称的相等性,这从长远来看是不好的(即,我想将json属性名称重写为更短的名称).解决方案的另一个问题是我需要通过PropertyInfo[]
,这在我看来并不直观.
So far i came up with passing PropertyInfo[]
which relies on Json / Class properties name equality which is not good in long run ( ie. i want to override json property name to something shorter ). Another issue with solution is that i need to pass PropertyInfo[]
which is not intuitive in my opinion.
也许有一种方法可以使用LINQ表达式以更好的方式重写此类.例如,像传递List<Func<T,TOut>>
然后通过反射编译和提取参数.它将更加动态,但无法解决Json/Class属性名称相等的问题.
Maybe there is a way to use LINQ expressions to rewrite this class in better way. For example like passing List<Func<T,TOut>>
then compiling and extracting parameters via reflection. It will be more dynamic but would not solve the issue with Json / Class property name equality.
任何建议,我都被卡住了....
Any suggestions, i'm stuck....
public class DynamicContractResolver : DefaultContractResolver
{
private readonly PropertyInfo[] m_propertiesExclusion;
public DynamicContractResolver(PropertyInfo[] propertiesExclusion)
{
m_propertiesExclusion = propertiesExclusion;
}
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
IList<JsonProperty> jsonProperties = base.CreateProperties(type, memberSerialization);
IEnumerable<string> filteredOutProperties = m_propertiesExclusion.Select(i => i.Name);
jsonProperties = jsonProperties
.Where(i => !filteredOutProperties.Contains(i.PropertyName))
.ToList();
return jsonProperties;
}
}
推荐答案
在这里,该实现采用任意数量的Expression<Func<T, object>>
并排除它们引用的属性.从表达式中提取属性名称的代码来自此答案.. >
Here's an implementation that takes any number of Expression<Func<T, object>>
s and excludes the properties they reference. The code for extracting property names from expressions was taken from this answer.
public class DynamicContractResolver<T> : DefaultContractResolver
{
private readonly HashSet<string> propertiesToExclude;
public DynamicContractResolver(
params Expression<Func<T, object>>[] propertyExpressions)
{
this.propertiesToExclude = new HashSet<string>();
foreach (Expression<Func<T, object>> expression in propertyExpressions)
{
string propertyName = GetPropertyNameFromExpression(expression);
this.propertiesToExclude.Add(propertyName);
}
}
protected override IList<JsonProperty> CreateProperties(
Type type, MemberSerialization memberSerialization)
{
IList<JsonProperty> jsonProperties =
base.CreateProperties(type, memberSerialization);
if (typeof(T).IsAssignableFrom(type))
{
jsonProperties = jsonProperties
.Where(pr => !this.propertiesToExclude.Contains(pr.PropertyName))
.ToList();
}
return jsonProperties;
}
// https://stackoverflow.com/a/2916344/497356
private string GetPropertyNameFromExpression(
Expression<Func<T, object>> expression)
{
MemberExpression body = expression.Body as MemberExpression;
if (body == null)
{
UnaryExpression ubody = (UnaryExpression)expression.Body;
body = ubody.Operand as MemberExpression;
}
return body.Member.Name;
}
}
以下是使用它的示例:
var resolver = new DynamicContractResolver<MyClass>(
mc => mc.MyIntegerProperty,
mc => mc.MyBoolProperty);
var myClass = new MyClass
{
MyIntegerProperty = 4,
MyStringProperty = "HELLO",
MyBoolProperty = true
};
var settings = new JsonSerializerSettings
{
ContractResolver = resolver,
Formatting = Newtonsoft.Json.Formatting.Indented
};
string serialized = JsonConvert.SerializeObject(
myClass, settings);
Console.WriteLine(serialized);
这篇关于通过反射进行动态json序列化过滤的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!