[转载]asp.net mvc 2 简简单单做开发 自定义DropdownList控件

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[转载]asp.net mvc 2 简简单单做开发 自定义DropdownList控件 – 飞创cms – 博客园.

ASP.NET mvc 2 给我们提供了强大的自定义功能,今天主要说下DropdownList自定义绑定字段显示,通过ViewData设定DropdownList的数据项。 自动绑定显示。实现的方式。在global.asax 中注册 FieldTemplateMetadataProvider,

ModelMetadataProviders.Current = new mvc.Models.FieldTemplateMetadataProvider();
通过返回的 FieldTemplateMetadata 。在MetaData中指定使用DropDownList的字段
[Display( Name=“”,Order=12)]
[Required]
[SearchFilter]
[DisplayName(“栏目”)]
[DropDownList(“Category”“Id”“Name”)]
public int Cid { getset; }

通过DropDownList指定 调用的模板为dropdownlist.ascx ,在dropdownlist.ascx 将默认的 ModelMetadata 转成FieldTemplateMetadata 获取 DropDownListAttribute 。

<script runat="server">
    DropDownListAttribute GetDropDownListAttribute()
    {
        FieldTemplateMetadata metaData = ViewData.ModelMetadata as FieldTemplateMetadata;
 
        return (metaData != null) ? metaData.Attributes.OfType<DropDownListAttribute>().SingleOrDefault() : null;
    }
</script>
 
  通过DropDownListAttribute 获得 ViewData的key ,绑定的文本对应的字段,值对应的字段,使用html.DropDownlist显示数据

DropdownList.ascx 代码

代码

<%@ Import Namespace=mvc.Models%>
<%@ Control Language=C# Inherits=System.Web.Mvc.ViewUserControl %>
<script runat=server>
DropDownListAttribute GetDropDownListAttribute()
{
FieldTemplateMetadata metaData
= ViewData.ModelMetadata as FieldTemplateMetadata;

return (metaData != null) ? metaData.Attributes.OfType<DropDownListAttribute>().SingleOrDefault() : null;
}
</script>
<% DropDownListAttribute attribute = GetDropDownListAttribute();%>
<% if (attribute != null) {%>
<%= Html.DropDownList(string.Empty, new SelectList(ViewData[attribute.ViewDataKey] as IEnumerable, attribute.DataValueField, attribute.DataTextField, Model), attribute.OptionLabel, attribute.HtmlAttributes) %>
<% }%>
<% else {%>
<%= Html.DisplayForModel() %>
<% }%>

自定义DropDownListAttribute 属性

代码

namespace mvc.Models
{
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web.Routing;

[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
public sealed class DropDownListAttribute : Attribute, ITemplateField
{
private static string defaultTemplateName;

public DropDownListAttribute(string viewDataKey, string dataValueField) : this(viewDataKey, dataValueField, null)
{
}

public DropDownListAttribute(string viewDataKey, string dataValueField, string dataTextField) : this(viewDataKey, dataValueField, dataTextField, null)
{
}

public DropDownListAttribute(string viewDataKey, string dataValueField, string dataTextField, string optionLabel) : this(DefaultTemplateName, viewDataKey, dataValueField, dataTextField, optionLabel, null)
{
}

public DropDownListAttribute(string viewDataKey, string dataValueField, string dataTextField, string optionLabel, object htmlAttributes) : this(DefaultTemplateName, viewDataKey, dataValueField, dataTextField, optionLabel, htmlAttributes)
{
}

public DropDownListAttribute(string templateName, string viewDataKey, string dataValueField, string dataTextField, string optionLabel, object htmlAttributes)
{
if (string.IsNullOrEmpty(templateName))
{
throw new ArgumentException(Template name cannot be empty.);
}

if (string.IsNullOrEmpty(viewDataKey))
{
throw new ArgumentException(View data key cannot be empty.);
}

if (string.IsNullOrEmpty(dataValueField))
{
throw new ArgumentException(Data value field cannot be empty.);
}

TemplateName = templateName;
ViewDataKey
= viewDataKey;
DataValueField
= dataValueField;
DataTextField
= dataTextField;
OptionLabel
= optionLabel;
HtmlAttributes
= new RouteValueDictionary(htmlAttributes);
}

public static string DefaultTemplateName
{
get
{
if (string.IsNullOrEmpty(defaultTemplateName))
{
defaultTemplateName
= DropDownList;
}

return defaultTemplateName;
}
set
{
defaultTemplateName
= value;
}
}

public string TemplateName { get; private set; }

public string ViewDataKey { get; private set; }

public string DataValueField { get; private set; }

public string DataTextField { get; private set; }

public string OptionLabel { get; private set; }

public IDictionary<string, object> HtmlAttributes { get; private set; }

public object GetSelectedValue(object model)
{
return GetPropertyValue(model, DataValueField);
}

public object GetSelectedText(object model)
{
return GetPropertyValue(model, !string.IsNullOrEmpty(DataTextField) ? DataTextField : DataValueField);
}

private static object GetPropertyValue(object model, string propertyName)
{
if (model != null)
{
PropertyDescriptor property
= GetTypeDescriptor(model.GetType()).GetProperties()
.Cast
<PropertyDescriptor>()
.SingleOrDefault(p
=> string.Compare(p.Name, propertyName, StringComparison.OrdinalIgnoreCase) == 0);

if (property != null)
{
return property.GetValue(model);
}
}

return null;
}

private static ICustomTypeDescriptor GetTypeDescriptor(Type type)
{
return new AssociatedMetadataTypeTypeDescriptionProvider(type).GetTypeDescriptor(type);
}
}
}

自定义DataAnnotationsModelMetadata

代码

public class FieldTemplateMetadata : DataAnnotationsModelMetadata
{
public FieldTemplateMetadata(DisplayAttribute aa, DataAnnotationsModelMetadataProvider provider, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName, DisplayColumnAttribute displayColumnAttribute, IEnumerable<Attribute> attributes) : base(provider, containerType, modelAccessor, modelType, propertyName, displayColumnAttribute)
{
Attributes
= new List<Attribute>(attributes);
Display
= aa;
}

public IList<Attribute> Attributes
{
get;
private set;
}
public DisplayAttribute Display { get; set; }
}

自定义 DataAnnotationsModelMetadataProvider

代码

public class FieldTemplateMetadataProvider : DataAnnotationsModelMetadataProvider
{
protected override ModelMetadata CreateMetadata(IEnumerable<Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName)
{
DataAnnotationsModelMetadata result
= (DataAnnotationsModelMetadata) base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName);

string templateName = attributes.OfType<ITemplateField>()
.Select(field
=> field.TemplateName)
.LastOrDefault();
List
<System.Attribute> attributeList = new List<System.Attribute>(attributes);
DisplayAttribute disp
= attributeList.OfType<DisplayAttribute>().FirstOrDefault();
if (disp != null)
{
result.ShortDisplayName
= disp.Order.ToString(); ;
result.Description
= disp.Description;
}

var data= (new FieldTemplateMetadata(disp, this, containerType, modelAccessor, modelType, propertyName, attributes.OfType<DisplayColumnAttribute>().FirstOrDefault(), attributes)

{
TemplateHint = !string.IsNullOrEmpty(templateName) ? templateName : result.TemplateHint,
HideSurroundingHtml
= result.HideSurroundingHtml,
DataTypeName
= result.DataTypeName,
IsReadOnly
= result.IsReadOnly,
NullDisplayText
= result.NullDisplayText,
DisplayFormatString
= result.DisplayFormatString,
ConvertEmptyStringToNull
= result.ConvertEmptyStringToNull,
EditFormatString
= result.EditFormatString,
ShowForDisplay
= result.ShowForDisplay,
ShowForEdit
= result.ShowForEdit,
DisplayName
= result.DisplayName,
Description
= result.Description,
ShortDisplayName
= result.ShortDisplayName,

});

SearchFilterAttribute searchFilterAttribute = attributes.OfType<SearchFilterAttribute>().FirstOrDefault();
if (searchFilterAttribute != null)
{
data.AdditionalValues.Add(
Search, searchFilterAttribute);
}

OrderByAttribute orderByAttribute = attributes.OfType<OrderByAttribute>().FirstOrDefault();
if (orderByAttribute != null)
{
data.AdditionalValues.Add(
OrderBy, orderByAttribute);
}
return data;
}
}

————————————————————————————
作者:王继坤
出处:http://www.wjk3.cn/
本文版权归作者和博客园共有,欢迎转 载,但未经作者同意必须保留此段声明,且在文章页面明显位置给出原文连接,否则保留追究法律责任的权利。
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