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

23:15:57     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

UpdateFrom
        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

PageUtility
    /**//// <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;
            }
        }
    }