递归映射扩展对象
本文关键字:对象 扩展 映射 递归 | 更新日期: 2023-09-27 18:36:25
在我的应用程序中,我必须使用 ExpandoObject 才能在运行时创建/删除属性;但是,我必须将函数返回的 ExpandoObject 映射到相应的对象/类。所以我想出了一个小型映射器来完成这项工作,但有 3 个问题:
- 它不会递归映射扩展对象的内部对象正如假设的那样。
- 当我尝试将 int 映射到可为空的 Null 时,它会抛出一个类型不匹配,因为我找不到正确检测和投射它的方法。
- 字段无法映射
public string Property;
。
法典:
一、实施:
public static class Mapper<T> where T : class
{
#region Properties
private static readonly Dictionary<string, PropertyInfo> PropertyMap;
#endregion
#region Ctor
static Mapper() { PropertyMap = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance).ToDictionary(p => p.Name.ToLower(), p => p); }
#endregion
#region Methods
public static void Map(ExpandoObject source, T destination)
{
if (source == null)
throw new ArgumentNullException("source");
if (destination == null)
throw new ArgumentNullException("destination");
foreach (var kv in source)
{
PropertyInfo p;
if (PropertyMap.TryGetValue(kv.Key.ToLower(), out p))
{
Type propType = p.PropertyType;
if (kv.Value == null)
{
if (!propType.IsByRef && propType.Name != "Nullable`1")
{
throw new ArgumentException("not nullable");
}
}
else if (kv.Value.GetType() != propType)
{
throw new ArgumentException("type mismatch");
}
p.SetValue(destination, kv.Value, null);
}
}
}
#endregion
}
二、用法:
public static void Main()
{
Class c = new Class();
dynamic o = new ExpandoObject();
o.Name = "Carl";
o.Level = 7;
o.Inner = new InnerClass
{
Name = "Inner Carl",
Level = 10
};
Mapper<Class>.Map(o, c);
Console.Read();
}
internal class Class
{
public string Name { get; set; }
public int? Level { get; set; }
public InnerClass Inner { get; set; }
public string Property;
}
internal class InnerClass
{
public string Name { get; set; }
public int? Level { get; set; }
}
3-如果属性的格式如下
public string Property;
则get属性不会获取它。
哦,那不是财产,那是田地。如果您还需要考虑字段。
static Mapper()
{
PropertyMap = typeof(T).GetProperties(BindingFlags.Public |
BindingFlags.NonPublic |
BindingFlags.Instance)
.ToDictionary(p => p.Name.ToLower(), p => p);
FieldMap = typeof(T).GetFields(BindingFlags.Public |
BindingFlags.NonPublic |
BindingFlags.Instance)
.ToDictionary(f => f.Name.ToLower(), f => f);
}
2-当我尝试将int映射到Nullable时,它会抛出类型不匹配,因为我找不到正确检测和强制转换它的方法。
为什么要检查Nullable
类型,让反射弄清楚。如果值有效,则将分配该值。
public static void Map(ExpandoObject source, T destination)
{
if (source == null)
throw new ArgumentNullException("source");
if (destination == null)
throw new ArgumentNullException("destination");
foreach (var kv in source)
{
PropertyInfo p;
if (PropertyMap.TryGetValue(kv.Key.ToLower(), out p))
{
p.SetValue(destination, kv.Value, null);
}
else
{
FieldInfo f;
if (FieldMap.TryGetValue(kv.Key.ToLower(), out f))
{
f.SetValue(destination, kv.Value);
}
}
}
}
1 - 它不会像假设的那样递归映射 ExpandoObject 的内部对象。
似乎至少对你的InnerClass
有用。
Class c = new Class();
dynamic o = new ExpandoObject();
o.Name = "Carl";
o.Level = 7;
o.Inner = new InnerClass
{
Name = "Inner Carl",
Level = 10
};
o.Property = "my Property value"; // dont forget to set this
Mapper<Class>.Map(o, c);
编辑:根据您的评论,我创建了两个重载方法MergeProperty
。您可以为字段编写类似的重载方法。
public static void MergeProperty(PropertyInfo pi, ExpandoObject source, object target)
{
Type propType = pi.PropertyType;
// dont recurse for value type, Nullable<T> and strings
if (propType.IsValueType || propType == typeof(string))
{
var sourceVal = source.First(kvp => kvp.Key == pi.Name).Value;
if(sourceVal != null)
pi.SetValue(target, sourceVal, null);
}
else // recursively map inner class properties
{
var props = propType.GetProperties(BindingFlags.Public |
BindingFlags.NonPublic |
BindingFlags.Instance);
foreach (var p in props)
{
var sourcePropValue = source.First(kvp => kvp.Key == pi.Name).Value;
var targetPropValue = pi.GetValue(target, null);
if (sourcePropValue != null)
{
if (targetPropValue == null) // replace
{
pi.SetValue(target, source.First(kvp => kvp.Key == pi.Name).Value, null);
}
else
{
MergeProperty(p, sourcePropValue, targetPropValue);
}
}
}
}
}
public static void MergeProperty(PropertyInfo pi, object source, object target)
{
Type propType = pi.PropertyType;
PropertyInfo sourcePi = source.GetType().GetProperty(pi.Name);
// dont recurse for value type, Nullable<T> and strings
if (propType.IsValueType || propType == typeof(string))
{
var sourceVal = sourcePi.GetValue(source, null);
if(sourceVal != null)
pi.SetValue(target, sourceVal, null);
}
else // recursively map inner class properties
{
var props = propType.GetProperties(BindingFlags.Public |
BindingFlags.NonPublic |
BindingFlags.Instance);
foreach (var p in props)
{
var sourcePropValue = sourcePi.GetValue(source, null);
var targetPropValue = pi.GetValue(target, null);
if (sourcePropValue != null)
{
if (targetPropValue == null) // replace
{
pi.SetValue(target, sourcePi.GetValue(source, null), null);
}
else
{
MergeProperty(p, sourcePropValue, targetPropValue);
}
}
}
}
}
您可以通过以下方式使用这些方法:
public static void Map(ExpandoObject source, T destination)
{
if (source == null)
throw new ArgumentNullException("source");
if (destination == null)
throw new ArgumentNullException("destination");
foreach (var kv in source)
{
PropertyInfo p;
if (PropertyMap.TryGetValue(kv.Key.ToLower(), out p))
{
MergeProperty(p, source, destination);
}
else
{
// do similar merge for fields
}
}
}