Question

我在运行时使用C＃中的反射从类对象访问属性值。

    public bool GetValue(string fieldName, out object fieldValue)
    {
        // Get type of current record
        Type curentRecordType = _currentObject.GetType();
        PropertyInfo property = curentRecordType.GetProperty(fieldName);

        if (property != null)
        {
            fieldValue = property.GetValue(_currentObject, null).ToString();
            return true;
        }
        else
        {
            fieldValue = null;
            return false;
        }
    }

我将Property Name作为参数：fieldName传递给此方法。现在，我需要在运行时从上面的类的子对象访问属性值那里的任何人都可以指导我如何访问子对象属性值？

Answer 1

由于您希望能够在任意嵌套的子对象上查找对象，因此您需要一个可以递归调用的函数。这很复杂，因为你可能有孩子会回顾他们的父母，所以你需要跟踪你之前在搜索中看过的对象。

static bool GetValue(object currentObject, string propName, out object value)
{
    // call helper function that keeps track of which objects we've seen before
    return GetValue(currentObject, propName, out value, new HashSet<object>());
}

static bool GetValue(object currentObject, string propName, out object value,
                     HashSet<object> searchedObjects)
{
    PropertyInfo propInfo = currentObject.GetType().GetProperty(propName);
    if (propInfo != null)
    {
        value = propInfo.GetValue(currentObject, null);
        return true;
    }
    // search child properties
    foreach (PropertyInfo propInfo2 in currentObject.GetType().GetProperties())
    {   // ignore indexed properties
        if (propInfo2.GetIndexParameters().Length == 0)
        {
            object newObject = propInfo2.GetValue(currentObject, null);
            if (newObject != null && searchedObjects.Add(newObject) &&
                GetValue(newObject, propName, out value, searchedObjects))
                return true;
        }
    }
    // property not found here
    value = null;
    return false;
}

如果您知道您的财产所处的子对象，您可以将路径传递给它，如下所示：

public bool GetValue(string pathName, out object fieldValue) 
{ 
    object currentObject = _currentObject;
    string[] fieldNames = pathName.Split(".");

    foreach (string fieldName in fieldNames)
    {
        // Get type of current record 
        Type curentRecordType = currentObject.GetType(); 
        PropertyInfo property = curentRecordType.GetProperty(fieldName); 

        if (property != null) 
        { 
            currentObject = property.GetValue(currentObject, null).ToString(); 
        } 
        else 
        { 
            fieldValue = null; 
            return false; 
        } 
    }
    fieldValue = currentObject;
    return true; 
}

您可以将其称为GetValue("foo", out val)。

，而不是像GetValue("foo.bar", out val)那样称呼它

Answer 2

使用反射获取子对象，然后使用反射以相同的方式获取值。

Answer 3

public void Main(){
    var containerObject = new ContainerObject();
    object propertyValue;
    object nestedPropertyValue;
    if(GetValue(containerObject, "FirstPropertyName", out propertyValue){
       bool success = GetValue(propertyValue, "NestedPropertyName", out nestedPropertyValue);
    } 

}

public bool GetValue(object currentObject, string propertyName, out object propertyValue)
{
    // Get type of current record
    var currentObjectType = currentObject.GetType();
    PropertyInfo propertyInfo = currentObjectType.GetProperty(propertyName);

    propertyValue = propertyInfo != null 
                    ?  propertyInfo.GetValue(currentObject,null)
                    :  null;
    return propertyValue == null;
}

C＃ - 从子类中获取属性值

3 个答案: