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](https://docs.microsoft.com/zh-cn/aspnet/core/mvc/views/tag-helpers/authoring)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](https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.TagHelpers/)，再好好瞅了瞅[TagHelper的文档](https://docs.microsoft.com/zh-cn/aspnet/core/mvc/views/tag-helpers/authoring) 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](https://coding.net/u/yimocoding/p/WeDemo/git/archive/LayuiTagHelper) [效果预览](https://dn-coding-net-production-pp.qbox.me/c77da03e-5911-4952-9b2a-06285df05f56.gif) 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 - `asp-items`:绑定单选项 类型为：`IEnumerable` - `asp-skin`:layui的皮肤样式，默认or原始  - `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 ### 为什么要封装？ 举个栗子 --- 绑定一个复选框组 原始写法： ``` @foreach (var item in Model.Items) { var isChecked = Model.Hobby.Contions(item.Value) ? "checked=\"checked\"" : ""; } ``` 而使用TagHelper封装之后： ``` ``` ### 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： ``` 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) ``` var currentValues = Generator.GetCurrentValues(ViewContext,For.ModelExplorer,expression: For.Name,allowMultiple: true); ``` 这3句代码是在[mvc自带的SelectTagHelper](https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.TagHelpers/SelectTagHelper.cs)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 { /// /// 复选框 /// /// /// 当Items为空时显示单个，且选择后值为true /// [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 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() { new SelectListItem() { Text = "男", Value = "男" }, new SelectListItem() { Text = "女", Value = "女"}, new SelectListItem() { Text = "不详", Value = "不详",Disabled=true } }; } ``` ## Radio单选框组件封装 - 标签名称：`cl-radio` - 标签属性： - `asp-for`:绑定的字段，必须指定 - `asp-items`:绑定单选项 类型为：`IEnumerable` 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 { /// /// 单选框 /// [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 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() { new SelectListItem() { Text = "男", Value = "男" }, new SelectListItem() { Text = "女", Value = "女"}, new SelectListItem() { Text = "不详", Value = "不详",Disabled=true } }; } ``` ## 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：`` ``` namespace LayuiTagHelper.TagHelpers { /// /// 开关 /// [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，还望园友指出。 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](https://coding.net/u/yimocoding/p/WeDemo/git/tree/LayuiTagHelper/LayuiTagHelper/TagHelpers)看看都实现了哪些组件 - [仓库地址](https://coding.net/u/yimocoding/p/WeDemo/git/tree/LayuiTagHelper) - 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](https://coding.net/u/yimocoding/p/WeDemo/git/archive/LayuiTagHelper)，[效果预览](https://dn-coding-net-production-pp.qbox.me/c77da03e-5911-4952-9b2a-06285df05f56.gif)