详解asp.net core封装layui组件示例分享

用什么封装？这里只是用了TagHelper，是啥？自己瞅文档去

在学习使用TagHelper的时候，最希望的就是能有个Demo能够让自己作为参考

• 怎么去封装一个组件？
• 不同的情况怎么去实现？
• 有没有更好更高效的方法？

找啊找啊找，最后跑去看了看mvc中的TagHelpers，再好好瞅了瞅TagHelper的文档

勉强折腾了几个组件出来，本来想一个组件一个组件写文章的，但是发现国庆已经结束了~

Demo下载

效果预览

代码仅供参考,有不同的意见也忘不吝赐教

Checkbox复选框组件封装

标签名称：cl-checkbox

标签属性： asp-for:绑定的字段，必须指定

1. asp-items:绑定单选项 类型为：IEnumerable<SelectListItem>
2. asp-skin:layui的皮肤样式，默认or原始
3. asp-title:若只是一个复选框时显示的文字，且未指定items，默认Checkbox的值为true

其中在封装的时候看源代码发现两段非常有用的代码

1.判断是否可以多选：

代码如下:

var realModelType = For.ModelExplorer.ModelType; //通过类型判断是否为多选 var _allowMultiple = typeof(string) != realModelType && typeof(IEnumerable).IsAssignableFrom(realModelType);

2.获取模型绑定的列表值(多选的情况)

代码如下:

var currentValues = Generator.GetCurrentValues(ViewContext,For.ModelExplorer,expression: For.Name,allowMultiple: true);

这3句代码是在mvc自带的SelectTagHelper中发现的.

因为core其实已经提供了非常多的TagHelper,比如常用的select就是很好的参考对象，封装遇到问题的时候去找找看指不定就又意外的收获.

CheckboxTagHelper代码

using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Razor.TagHelpers;

namespace LayuiTagHelper.TagHelpers
{
 /// <summary>
 /// 复选框
 /// </summary>
 /// <remarks>
 /// 当Items为空时显示单个，且选择后值为true
 /// </remarks>
 [HtmlTargetElement(CheckboxTagName)]
 public class CheckboxTagHelper : TagHelper
 {
  private const string CheckboxTagName = "cl-checkbox";
  private const string ForAttributeName = "asp-for";
  private const string ItemsAttributeName = "asp-items";
  private const string SkinAttributeName = "asp-skin";
  private const string SignleTitleAttributeName = "asp-title";
  protected IHtmlGenerator Generator { get; }
  public CheckboxTagHelper(IHtmlGenerator generator)
  {
   Generator = generator;
  }

  [ViewContext]
  public ViewContext ViewContext { get; set; }

  [HtmlAttributeName(ForAttributeName)]
  public ModelExpression For { get; set; }

  [HtmlAttributeName(ItemsAttributeName)]
  public IEnumerable<SelectListItem> Items { get; set; }

  [HtmlAttributeName(SkinAttributeName)]
  public CheckboxSkin Skin { get; set; } = CheckboxSkin.默认;

  [HtmlAttributeName(SignleTitleAttributeName)]
  public string SignleTitle { get; set; }

  public override void Process(TagHelperContext context, TagHelperOutput output)
  {
   //获取绑定的生成的Name属性
   string inputName = ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(For?.Name);
   string skin = string.Empty;
   #region 风格
   switch (Skin)
   {
    case CheckboxSkin.默认:
     skin = "";
     break;
    case CheckboxSkin.原始:
     skin = "primary";
     break;
   }
   #endregion
   #region 单个复选框
   if (Items == null)
   {
    output.TagName = "input";
    output.TagMode = TagMode.SelfClosing;
    output.Attributes.Add("type", "checkbox");
    output.Attributes.Add("id", inputName);
    output.Attributes.Add("name", inputName);
    output.Attributes.Add("lay-skin", skin);
    output.Attributes.Add("title", SignleTitle);
    output.Attributes.Add("value", "true");
    if (For?.Model?.ToString().ToLower() == "true")
    {
     output.Attributes.Add("checked", "checked");
    }
    return;
   }
   #endregion
   #region 复选框组
   var currentValues = Generator.GetCurrentValues(ViewContext,For.ModelExplorer,expression: For.Name,allowMultiple: true);
   foreach (var item in Items)
   {
    var checkbox = new TagBuilder("input");
    checkbox.TagRenderMode = TagRenderMode.SelfClosing;
    checkbox.Attributes["type"] = "checkbox";
    checkbox.Attributes["id"] = inputName;
    checkbox.Attributes["name"] = inputName;
    checkbox.Attributes["lay-skin"] = skin;
    checkbox.Attributes["title"] = item.Text;
    checkbox.Attributes["value"] = item.Value;
    if (item.Disabled)
    {
     checkbox.Attributes.Add("disabled", "disabled");
    }
    if (item.Selected || (currentValues != null && currentValues.Contains(item.Value)))
    {
     checkbox.Attributes.Add("checked", "checked");
    }

    output.Content.AppendHtml(checkbox);
   }
   output.TagName = "";
   #endregion
  }
 }
 public enum CheckboxSkin
 {
  默认,
  原始
 }
}

使用示例

@{
string sex="男";
var Items=new List<SelectListItem>()
   {
    new SelectListItem() { Text = "男", Value = "男" },
    new SelectListItem() { Text = "女", Value = "女"},
    new SelectListItem() { Text = "不详", Value = "不详",Disabled=true }
   };
}
<cl-checkbox asp-items="Model.Items" asp-for="Hobby1" asp-skin="默认"></cl-checkbox>
<cl-checkbox asp-for="Hobby3" asp-title="单个复选框"></cl-checkbox>

Radio单选框组件封装

标签名称：cl-radio

1. 标签属性： asp-for:绑定的字段，必须指定
2. asp-items:绑定单选项 类型为：IEnumerable<SelectListItem>

太简单了，直接上代码了

RadioTagHelper代码

using System;
using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Razor.TagHelpers;

namespace LayuiTagHelper.TagHelpers
{
 /// <summary>
 /// 单选框
 /// </summary>
 [HtmlTargetElement(RadioTagName)]
 public class RadioTagHelper : TagHelper
 {
  private const string RadioTagName = "cl-radio";
  private const string ForAttributeName = "asp-for";
  private const string ItemsAttributeName = "asp-items";

  [ViewContext]
  public ViewContext ViewContext { get; set; }

  [HtmlAttributeName(ForAttributeName)]
  public ModelExpression For { get; set; }

  [HtmlAttributeName(ItemsAttributeName)]
  public IEnumerable<SelectListItem> Items { get; set; }

  public override void Process(TagHelperContext context, TagHelperOutput output)
  {
   if (For == null)
   {
    throw new ArgumentException("必须绑定模型");
   }
   foreach (var item in Items)
   {
    var radio = new TagBuilder("input");
    radio.TagRenderMode = TagRenderMode.SelfClosing;
    radio.Attributes.Add("id", ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(For.Name));
    radio.Attributes.Add("name", ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(For.Name));
    radio.Attributes.Add("value", item.Value);
    radio.Attributes.Add("title", item.Text);
    radio.Attributes.Add("type", "radio");
    if (item.Disabled)
    {
     radio.Attributes.Add("disabled", "disabled");
    }
    if (item.Selected || item.Value == For.Model?.ToString())
    {
     radio.Attributes.Add("checked", "checked");
    }
    output.Content.AppendHtml(radio);
   }
   output.TagName = "";
  }
 }
}

使用示例

@{
string sex="男";
var Items=new List<SelectListItem>()
   {
    new SelectListItem() { Text = "男", Value = "男" },
    new SelectListItem() { Text = "女", Value = "女"},
    new SelectListItem() { Text = "不详", Value = "不详",Disabled=true }
   };
}
<cl-radio asp-items="@Items" asp-for="sex"></cl-radio>

最后再来一个开关组件

单个复选框其实可以直接用开关代替，恰巧layui中也有，于是也将开关单独的封装了一下，代码大同小异

就这个 

使用也简单： <cl-switch asp-for="Hobby4" asp-switch-text="开启|关闭"></cl-switch>


namespace LayuiTagHelper.TagHelpers
{
 /// <summary>
 /// 开关
 /// </summary>
 [HtmlTargetElement(SwitchTagName)]
 public class SwitchTagHelper : TagHelper
 {
  private const string SwitchTagName = "cl-switch";
  private const string ForAttributeName = "asp-for";
  private const string SwitchTextAttributeName = "asp-switch-text";

  protected IHtmlGenerator Generator { get; }
  public SwitchTagHelper(IHtmlGenerator generator)
  {
   Generator = generator;
  }

  [ViewContext]
  public ViewContext ViewContext { get; set; }

  [HtmlAttributeName(ForAttributeName)]
  public ModelExpression For { get; set; }

  [HtmlAttributeName(SwitchTextAttributeName)]
  public string SwitchText { get; set; } = "ON|OFF";

  public override void Process(TagHelperContext context, TagHelperOutput output)
  {
   string inputName = ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(For?.Name);
   output.TagName = "input";
   output.TagMode = TagMode.SelfClosing;
   if (For?.Model?.ToString().ToLower() == "true")
   {
    output.Attributes.Add("checked", "checked");
   }
   output.Attributes.Add("type", "checkbox");
   output.Attributes.Add("id", inputName);
   output.Attributes.Add("name", inputName);
   output.Attributes.Add("value", "true");
   output.Attributes.Add("lay-skin", "switch");
   output.Attributes.Add("lay-text", SwitchText);

  }
 }
}

总结

封装的还很粗糙，正常的使用是没问题的，若发现问题，还望指出。

因为layui是直接在页面加载后渲染的表单标签，故没有多少和layui相关的样式。

除了一些表单组件之外，其实还对选项卡，时间轴，分页，代码显示组件做了一些封装，这些后面再介绍了。

当然，有兴趣的朋友可以先去一睹为快看看都实现了哪些组件

仓库地址

WeDemo分支clone命令:git clone https://git.coding.net/yimocoding/WeDemo.git -b LayuiTagHelper

选项卡，时间轴，分页，代码显示等Demo打包下载

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