[英]How do I get the FieldInfo of an array field?
I'm trying to get the field info of an array value from within a struct. 我正在尝试从结构中获取数组值的字段信息。 So far I have the following, but I dont see how to get the infomration I want. 到目前为止,我有以下内容,但我没有看到如何获得我想要的信息。
[StructLayout(LayoutKind.Sequential)]
public struct Test
{
public byte Byte1;
[MarshalAs(UnmanagedType.ByValArray, SizeConst=3)]
public Test2[] Test1;
}
BindingFlags struct_field_flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance | BindingFlags.DeclaredOnly;
FieldInfo[] all_struct_fields = typeof(Test).GetFields(struct_field_flags);
foreach (FieldInfo struct_field in all_struct_fields)
{
if(struct_field.FieldType.IsArray)
{
// Get FieldInfo for each value in the Test1 array within Test structure
}
}
So if I did: 所以,如果我这样做:
Type array_type = struct_field.FieldType.GetElementType();
This would return Test2 type, but I dont want the type of the array, I want the FieldInfo or Fields of that structure so I can set values from within it. 这将返回Test2类型,但我不想要数组的类型,我想要FieldInfo或该结构的Fields,以便我可以在其中设置值。
What exactly are you after? 你到底是什么人? There is no FieldInfo
for the items in the array... you can iterate the values by getting the array (as Array
) and iterating it... just use: 没有 FieldInfo
为阵列...你可以通过获取阵列(如重复的值中的项目Array
)和迭代...只是使用:
Array arr = (Array)field.GetValue(obj);
Sorry for the initial wrong answer. 抱歉,最初的错误答案。 I was too lazy to create my own Test2 type so I used a string instead. 我懒得创建自己的Test2类型,所以我用了一个字符串代替。 Here's the right answer (hopefully): 这是正确的答案(希望如此):
I did what you want to do with the following code: 我用以下代码做了你想做的事:
class Program
{
static void Main(string[] args)
{
object sampleObject = GetSampleObject();
FieldInfo[] testStructFields = typeof(Test).GetFields();
foreach (FieldInfo testStructField in testStructFields)
{
if (testStructField.FieldType.IsArray)
{
// We can cast to ILIst because arrays implement it and we verfied that it is an array in the if statement
System.Collections.IList sampleObject_test1 = (System.Collections.IList)testStructField.GetValue(sampleObject);
// We can now get the first element of the array of Test2s:
object sampleObject_test1_Element0 = sampleObject_test1[0];
// I hope this the FieldInfo that you want to get:
FieldInfo myValueFieldInfo = sampleObject_test1_Element0.GetType().GetField("MyValue");
// Now it is possible to read and write values
object sampleObject_test1_Element0_MyValue = myValueFieldInfo.GetValue(sampleObject_test1_Element0);
Console.WriteLine(sampleObject_test1_Element0_MyValue); // prints 99
myValueFieldInfo.SetValue(sampleObject_test1_Element0, 55);
sampleObject_test1_Element0_MyValue = myValueFieldInfo.GetValue(sampleObject_test1_Element0);
Console.WriteLine(sampleObject_test1_Element0_MyValue); // prints 55
}
}
}
static object GetSampleObject()
{
Test sampleTest = new Test();
sampleTest.Test1 = new Test2[5];
sampleTest.Test1[0] = new Test2() { MyValue = 99 };
object sampleObject = sampleTest;
return sampleObject;
}
}
[StructLayout(LayoutKind.Sequential)]
public struct Test2
{
public int MyValue;
}
[StructLayout(LayoutKind.Sequential)]
public struct Test
{
public byte Byte1;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
public Test2[] Test1;
}
This is the most important line: 这是最重要的一句话:
FieldInfo myValueFieldInfo = sampleObject_test1_Element0.GetType().GetField("MyValue");
It should give you the FieldInfo that you are talking about. 它应该为您提供您正在谈论的FieldInfo。
The problem with @weiqure's technique is that it only works if the array already has at least one element in it. @ weiqure技术的问题在于它只有在数组中至少有一个元素时才有效。 Here is a way to find the array's element type, whether it contains elements or not: 这是一种查找数组元素类型的方法,无论它是否包含元素:
bool GetArrayElementType(FieldInfo field, out Type elementType)
{
if (field.FieldType.IsArray && field.FieldType.FullName.EndsWith("[]"))
{
string fullName = field.FieldType.FullName.Substring(0, field.FieldType.FullName.Length - 2);
elementType = Type.GetType(string.Format("{0},{1}", fullName, field.FieldType.Assembly.GetName().Name));
return true;
}
elementType = null;
return false;
}
And here is how you would use that function: 以下是您将如何使用该功能:
void Test(object targetObject, string fieldName)
{
FieldInfo field = targetObject.GetType().GetField(fieldName);
Type elementType;
bool success = GetArrayElementType(field, out elementType);
}
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