如何为静态字段分配值动态创建对象？

Question

I want to create an object using reflection class PropertyCondition(in assembly UIAutomationClient.dll) . In order to obtain the desired class constructor, I use the following code:

var assembly = AppDomain.CurrentDomain.GetAssemblies().First(x => x.FullName.Contains("AutomationClient"));

var propertyConditionType = assembly.DefinedTypes.First(x => x.Name == "PropertyCondition");
var automationElementType = assembly.DefinedTypes.First(x => x.Name == "AutomationElement");

var automationIdPropertyType = automationElementType.GetField("AutomationIdProperty").FieldType;
var constructor = propertyConditionType.GetConstructor(new Type[] { automationIdPropertyType, typeof(object) });

But how do I pass in constructor AutomationElement.AutomationIdProperty ?

Thank you.

Answer 1

I belive that automationId is a string property . And what you need is find constructor which accepts strings :

ConstructorInfo ctor = propertyConditionType.GetConstructor(new[] { typeof(string) });
object instance = ctor.Invoke(new object[] { automationId });

Or you can use Activator.CreateInstance Method :

CreateInstance(AppDomain, String, String, Boolean, BindingFlags, Binder, Object[], CultureInfo, Object[])

Creates an instance of the type whose name is specified in the specified remote domain, using the named assembly and the constructor that best matches the specified parameters.

Answer 2

The step you are missing is a simple FieldInfo.GetValue call, to get the value you have to pass into the constructor. I restructured your code:

var automationIdPropertyField = automationElementType.GetField("AutomationIdProperty");

var automationIdPropertyType = automationIdPropertyField.FieldType;
var automationIdPropertyValue = automationIdPropertyField.GetValue(null);

var constructor = propertyConditionType.GetConstructor(new[] { automationIdPropertyType, typeof(object) });

var obj = constructor.Invoke(new[] {automationIdPropertyValue, ...});