通过与不同的属性类型的反射设定对象的属性 [英] Setting properties of an object through reflection with different properties types

问题描述

我使用反射来填充对象的属性。

I am using reflection to populate the properties of an object.

这些属性有不同的类型：字符串，可空（双）和可空（长）（不知道如何逃离这里尖括号......）。 。这些属性的值是从（字符串，对象）对的字典来

These properties have different types: String, Nullable(double) and Nullable(long) (don't know how to escape the angle brackets here ...). The values for these properties are coming from a dictionary of (string, object) pairs.

因此​​，例如我的类具有以下属性：

So, for example my class has the following properties:

string Description { get; set; } 
Nullable<long> Id { get; set; }
Nullable<double> MaxPower { get; set; }

（现实中有十几属性）和字典将有条目类似<说明，说明><ID，123456>，<牛魔王，20000>

(in reality there are about a dozen properties) and the dictionary will have entries like <"Description", "A description">, <"Id", 123456>, <"MaxPower", 20000>

现在我使用类似以下内容设置的值：

Now I am using something like the following to set the values:

foreach (PropertyInfo info in this.GetType().GetProperties())
{
    if (info.CanRead)
    {
         object thisPropertyValue = dictionary[info.Name];

         if (thisPropertyValue != null && info.CanWrite)
         {
             Type propertyType = info.PropertyType;

             if (propertyType == typeof(String))
             {
                 info.SetValue(this, Convert.ToString(thisPropertyValue), null);
             }
             else if (propertyType == typeof(Nullable<double>))
             {
                 info.SetValue(this, Convert.ToDouble(thisPropertyValue), null);
             }
             else if (propertyType == typeof(Nullable<long>))
             {
                 info.SetValue(this, Convert.ToInt64(thisPropertyValue), null);
             }
             else
             {
                 throw new ApplicationException("Unexpected property type");
             }
         }
     }
}

所以，问题是：我真的有指定的值之前，检查每个属性的类型？有没有像投什么我可以执行，这样属性值分配相应属性的类型？

So the question is: do I really have to check the type of each property before assigning the value? Is there anything like a cast that I can perform so that the property value is assigned the type of the corresponding property?

在理想情况下，我想能做点什么像的以下（这是我天真地以为本来是可行的）：

Ideally I would like to be able to do something like the following (which I naively thought might have worked):

         if (thisPropertyValue != null && info.CanWrite)
         {
             Type propertyType = info.PropertyType;

             if (propertyType == typeof(String))
             {
                 info.SetValue(this, (propertyType)thisPropertyValue, null);
             }
        }

谢谢，
斯特凡诺

Thanks, Stefano

推荐答案

如果该值已正确类型的，则没有：你没有做任何事情。如果他们可能不适合（INT VS浮点等），在一个简单的方法可能是：

If the values are already of the correct type, then no: you don't have to do anything. If they might not be right (int vs float, etc), the a simple approach might be:

（修改空值调整）

Type propertyType = info.PropertyType;
if (thisPropertyValue != null)
{
    Type underlyingType = Nullable.GetUnderlyingType(propertyType);
    thisPropertyValue = Convert.ChangeType(
        thisPropertyValue, underlyingType ?? propertyType);
}
info.SetValue(this, thisPropertyValue, null);

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