实现WebForm下面的自动收集对象属性(与MVC下在的UpdateFrom一样)

对ASP.net MVC有了解的同学估计都对里面的UpdateFrom方法有较深的印象。它接受一个对象参数，然后，它会对任何匹配该对象的公开属性，自动对本身进行属性赋值。这样的功能都引来一片叫好声。可惜的是他只能在MVC下使用。那么在WebForm下面就不能实现这样的功能了吗？答案是可以的，其实还可以做得更好。这里把以前的代码翻出来晒晒。

我们还是先看一下UpdateFrom的实现。其实实现很简单，就是先用反射取得对象的所有的属性。然后在Requet.QuerySting或Requet.Form中查找对应的键。如果 找到了对应的值就再调用Property.SetValue方法对其设置属性值。代码如下


public static void UpdateFrom(this object obj, NameValueCollection values, string objectPrefix)




...{


Type objType = obj.GetType();


string objName = objType.Name;


StringBuilder exceptionList = new StringBuilder();




PropertyInfo[] fields = objType.GetProperties();




PopulateTypeException ex = null;




foreach (PropertyInfo property in fields)




...{




//check the key


//going to be forgiving here, allowing for full declaration


//or just propname


string httpKey = property.Name;




if (objectPrefix != string.Empty)


httpKey = objectPrefix + httpKey;




if (values[httpKey] == null)




...{


httpKey = objName + "." + property.Name;


}




if (values[httpKey] == null)




...{


httpKey = objName + "_" + property.Name;


}






if (values[httpKey] != null)




...{


TypeConverter conv = TypeDescriptor.GetConverter(property.PropertyType);


object value = values[httpKey];




if (conv.CanConvertFrom(typeof(string)))




...{


try




...{


value = conv.ConvertFrom(values[httpKey]);


property.SetValue(obj, value, null);




}


catch (Exception e)




...{


string message = property.Name + " is not a valid " + property.PropertyType.Name + "; " + e.Message;


if (ex == null)


ex = new PopulateTypeException("Errors occurred during object binding - review the LoadExceptions property of this exception for more details");




PopulateTypeException.ExceptionInfo info = new PopulateTypeException.ExceptionInfo();


info.AttemptedValue = value;


info.PropertyName = property.Name;


info.ErrorMessage = message;




ex.LoadExceptions.Add(info);




}


}


else




...{


throw new Exception("No type converter available for type: " + property.PropertyType);


}


}


}


if (ex != null)


throw ex;




}

下面进入正题。看看在Webform下面的实现，思路还是一样的。先把我的实现代码贴上来再说

/// <summary>
/// 根据对象自动给相应控件取值或者赋值
/// </summary>
public class ValuePicker
{
/// <summary>
/// 把对象赋值给相应控件
/// </summary>
/// <param name="dataEntity">对象</param>
/// <param name="page">要搜索控件的Page或者Master里的ContentPlaceHolder</param>
/// <returns></returns>
public int SetValue(object dataEntity, Control page)
{
return OperateValue(dataEntity, page, true);
}
/// <summary>
/// 把相应控件的属性值赋给对象的相应属性
/// </summary>
/// <param name="dataEntity">对象</param>
/// <param name="page">要搜索控件的Page或者Master里的ContentPlaceHolder</param>
/// <returns></returns>
public int GetValue(object dataEntity, Control page)
{
return OperateValue(dataEntity, page, false);
}
/// <summary>
/// 根据每个控件的类型，获取对应操作的属性名称
/// </summary>
/// <param name="typeName">控件类型</param>
/// <returns></returns>
private string GetPropertyTypeName(string typeName)
{
switch (typeName)
{
case "TextBox":
return "Text";
case "DropDownList":
return "SelectedValue";
case "CheckBox":
return "Checked";
case "HiddenField":
return "Value";
default:
return "Text";
}
}
/// <summary>
/// 具体实现赋值和取值的方法
/// </summary>
/// <param name="dataEntity">对象</param>
/// <param name="page">要搜索控件的Page或者Master里的ContentPlaceHolder</param>
/// <param name="isSetting">是否是要设置控件的值</param>
/// <returns></returns>
private int OperateValue(object dataEntity, Control page, bool isSetting)
{
try
{
Type EntityType = dataEntity.GetType();
Type ControlType;
//取得所有的属性
PropertyInfo[] Pinfos = EntityType.GetProperties(); ;
Control Ctrl;
Object Data = null;
string PropertyTypeName;
//遍历所有的属性
foreach (PropertyInfo Pinfo in Pinfos)
{
//查找属性对应的控件
Ctrl = page.FindControl(Pinfo.Name);
if (Ctrl != null)
{
ControlType = Ctrl.GetType();
//取得控件存储值的属性
PropertyTypeName = GetPropertyTypeName(ControlType.Name);

if (isSetting == true)
{//把对象的值设置给控件
Data = EntityType.InvokeMember(Pinfo.Name,
BindingFlags.GetProperty, null, dataEntity, null);
Data = ReDefineData(ControlType, Data, PropertyTypeName);
object[] SettingData = { Data };
ControlType.InvokeMember(PropertyTypeName,
BindingFlags.SetProperty, null, Ctrl, SettingData);
}
else
{//取得控件的值赋给对象对应的属性
Data = ControlType.InvokeMember(PropertyTypeName,
BindingFlags.GetProperty, null, Ctrl, null);
Data = ReDefineData(EntityType, Data, Pinfo.Name);

object[] SettingData = { Data };
EntityType.InvokeMember(Pinfo.Name,
BindingFlags.SetProperty, null, dataEntity, SettingData);
}
}
}
return 0;
}
catch (System.Exception E)
{
System.Diagnostics.Debug.WriteLine(E.ToString());
//注意
throw (E);
return -1;
}
}

/// <summary>
/// 进行数据类型转换
/// </summary>
/// <param name="controlType"></param>
/// <param name="data"></param>
/// <param name="PropertyTypeName"></param>
/// <returns></returns>
private object ReDefineData(Type controlType, Object data, string PropertyTypeName)
{
if (data == null)
return null;
switch (controlType.GetProperty(PropertyTypeName).PropertyType.Name)
{
case "Boolean":
if ((int)data == 1)
data = true;
else
data = false;
break;

case "String":
data = data.ToString();
break;
case "Int32":
data = Convert.ToInt32(data);
break;
case "Double":
data = Convert.ToDouble(data);
break;
default:
break;
}
return data;
}
}

在GetPropertyTypeName里面的类型还不够多。比如如果你用到了RadioButtonList，你可以自己加上对应的属性SelectedValue，在这里就只列这么多了。你可以自己改成更好的实现方法。另外ReDefineData应该也要相应的添加一些对应关现。在看了UpdateFrom的实现以后，其实这个类异常的处理应该要改成UpdateFrom才更好，这里就不改了，有空的话我会再改进一下。
另外你还可以写一个类以方便调用




/**//// <summary>


/// 提供页面操作的常用函数


/// </summary>


public class PageUtility




...{




/**//// <summary>


/// 设置当前页面上的控件值


/// </summary>


/// <param name="dataEntity">源数据</param>


/// <returns></returns>


public static int SetPageValueForM(object dataEntity)




...{


ValuePicker Vp = new ValuePicker();


Control ctl = CurPage.Master.FindControl("ContentPlaceHolder2");


return Vp.SetValue(dataEntity, ctl);


}






/**//// <summary>


/// 把当前页面的值读取到控件


/// </summary>


/// <param name="dataEntity">取值的对象</param>


/// <returns></returns>


public static int GetPageValueForM(object dataEntity)




...{


ValuePicker Vp = new ValuePicker();


Control ctl = CurPage.Master.FindControl("ContentPlaceHolder2");


return Vp.GetValue(dataEntity, ctl);


}






/**//// <summary>


/// 把当前页面的值读取到控件


/// </summary>


/// <param name="dataEntity">取值的对象</param>


/// <returns></returns>


public static int GetPageValue(object dataEntity)




...{


ValuePicker Vp = new ValuePicker();


return Vp.GetValue(dataEntity, CurPage);


}






/**//// <summary>


/// 设置当前页面上的控件值


/// </summary>


/// <param name="dataEntity">源数据</param>


/// <returns></returns>


public static int SetPageValue(object dataEntity)




...{


ValuePicker Vp = new ValuePicker();


return Vp.SetValue(dataEntity, CurPage);


}








/**//// <summary>


/// 返回当前页面类


/// </summary>


public static Page CurPage




...{




get ...{ return System.Web.HttpContext.Current.Handler as Page; }


}


}