反思：如何通过 PropertyInfo 获取类对象

Question

I have 2 classes. ClassA has some objects of ClassB called Field01, Field02, ... Class A also has a list of ClassB items.

I know the name of the ClassB items and want to fill the ClassB items with the values from the list.

Example code:

public class ClassA
{
    public ClassB Field01 {get;set;}
    public ClassB Field02 {get;set;}
    //...

    List<ClassB> myItems;

    public void FillItems()
    {
        foreach(var item in MyItems)
        {
           // what I want in hardcode:
           Field01.ValueA = MyItems[0].ValueA;
           Field01.ValueB = MyItems[0].ValueB;
           Field02.ValueA = MyItems[1].ValueA;
           // ...
        }
    }
}

public class ClassB 
{
    public string ValueA {get;set;}
    public string ValueB {get;set;}
}

In my case I'll have a counting variable which will create the Field01, Field02, Field03, ... names depending on how many items are in my List (there are always enough ClassB fields in ClassA to fill)

I know i can get the PropertyInfo of my ClassB items via name, but I don't know you I can access the ClassB attributes ValueA and ValueB

// If ClassB was just a string or object this would work
Type myType = typeof(ClassA);
PropertyInfo myPropInfo = myType.GetProperty("Field01");
myPropInfo.SetValue(this, "Hello", null);

Answer 1

Since you know the declaring type of the properties is ClassB , you can get the PropertyInfo of ValueA and ValueB . Then, you need to get the value of FieldXX (not set it!) and set ValueA and ValueB .

We are going to be dealing with multiple Type , PropertyInfo and object objects, so you should name your variables appropriately, instead of just myPropInfo or myType .

for (int i = 0 ; i < MyItems.Count ; i++) {
    var classAType = typeof(ClassA);
    var classBType = typeof(ClassB);
    var fieldInfo = classAType.GetProperty("Field" + $"{i}".PadLeft(2, '0'));
    var fieldValue = fieldInfo.GetValue(this);
    var valueAInfo = classBType.GetProperty(nameof(ClassB.ValueA));
    var valueBInfo = classBType.GetProperty(nameof(ClassB.ValueB));
    valueAInfo.SetValue(fieldValue, valueAInfo.GetValue(MyItems[i]));
    valueBInfo.SetValue(fieldValue, valueBInfo.GetValue(MyItems[i]));
}