C＃反射-類型錯誤

Question

string assembly = "Ektron.Cms.ObjectFactory.dll";
string asspath = path + "bin\\" + assembly;
Assembly run_obj = Assembly.LoadFrom(@asspath);
paraObj[0] = run_obj.GetType(
    "Ektron.Cms.Search.SearchContentProperty",
    true,
    true
).GetProperty("Language");

string equalExp = "Ektron.Cms.Search.Expressions.EqualsExpression";
Type objclass = run_obj.GetType(equalExp, true, true);       
object objObj = Activator.CreateInstance(objclass, paraObj);

Activator.CreateInstance(objclass, paraObj)引發錯誤：

無法將System.Reflection.RuntimeParameterInfo隱式轉換為Ektron.Cms.Search.Expresions.PropertyExpression

Answer 1

存儲在paraObj[0]值的類型為RuntimeParameterInfo ，而EqualsExpression的構造EqualsExpression期望一個類型為PropertyExpression的對象。 您需要確保可以將paraObj中的對象類型綁定到合適的構造函數，以便Activator能夠實例化新對象。

要解決您的問題，您需要創建一個PropertyExpression實例，並將其用作paraObj數組中的第一個元素：

string assembly = "Ektron.Cms.ObjectFactory.dll";
string asspath = path + "bin\\" + assembly;
Assembly run_obj = Assembly.LoadFrom(@asspath);

PropertyInfo propertyInfo = run_obj.GetType("Ektron.Cms.Search.SearchContentProperty", true, true).GetProperty("Language");
PropertyExpression propertyExpression = new PropertyExpression(propertyInfo); // create the property expression here, I am unsure how to instantiate it.
paraObj[0] = propertyExpression;
paraObj[1] = longValue;

string equalExp = "Ektron.Cms.Search.Expressions.EqualsExpression";
Type objclass = run_obj.GetType(equalExp, true, true);       
object objObj = Activator.CreateInstance(objclass, paraObj);

Answer 2

您沒有提供構造函數從您的代碼中期望的類型，很明顯，您正在傳遞PropertyInfo 。

如果您需要屬性中的值，則PropertyInfo指向您，則必須使用PropertyInfo.GetValue

我正在從您的代碼段中推測（因為我沒有Ektron代碼），因此您應該執行以下操作：

var propInfo  = run_obj.GetType(
                  "Ektron.Cms.Search.SearchContentProperty",
                   true,true).GetProperty("Language");

paraObj[0] = propInfo.GetValue(null,null)  //depending on the requirement