MVC Core 使用TagHelper扩展几个插件

未完待续...

案例1：按钮权限校验，无权限不显示，利用TagHelper控制元素是否输出

    [HtmlTargetElement("tc-permission", TagStructure = TagStructure.NormalOrSelfClosing)]
    public class TCPermissionTagHelper : TagHelper
    {
        private IPermissionContext permissionContext = null;
        public TCPermissionTagHelper(IPermissionContext permissionContext)
        {
            this.permissionContext = permissionContext;
        }

        public string[] Permissions { get; set; }
        public string Permission { get; set; }

        public override void Process(TagHelperContext context, TagHelperOutput output)
        {
            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }

            if (output == null)
            {
                throw new ArgumentNullException(nameof(output));
            }
            output.TagName = null;
            if (!string.IsNullOrEmpty(Permission))
            {
                Permissions = Permission.SplitToArray<string>();
            }
            //HasPermission:根据UserID、按钮权限编码判断用户是否有此按钮权限，如果无权就不输出
            if (Permissions == null || Permissions.Length ==  || !permissionContext.HasPermission(Permissions))
            {
                output.SuppressOutput();
                return;
            }

        }
    }

页面中添加：

<tc-permission permission="@Permissions.系统模块.账户管理.添加">
            <a id="btnAdd" class="btn  btn-primary" onclick="cache.add(); return false;">添加</a>
        </tc-permission>

lable-input插件：

     [HtmlTargetElement("label-input")]
     public class FieldTagHelper : TagHelper
     {
         public string FieldName { get; set; }
         public string Label { get; set; }
         public string Value { get; set; }
         public string PlaceHolder { get; set; }
         public override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
         {
             output.TagName = "div";
             output.Attributes.Add("class", "form-group");
             output.Content.SetHtmlContent(
                 $@"<label for='{FieldName}'>{Label}</label>
                    <input type='text' id='{FieldName}' name='{FieldName}' value='{Value}'>");

             return base.ProcessAsync(context, output);
         }
     }

Enum版Select：

     /// <summary>
     /// Enum版Select
     /// </summary>
     [HtmlTargetElement("select-enum")]
     public class SelectEnumTagHelper : TagHelper
     {
         public Type EnumType { get; set; }
         public object Value { get; set; }
         public string Placeholder { get; set; }
         //public Dictionary<string, object> Attributes { get; set; }
         public override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
         {
             output.TagName = "select";
             StringBuilder buffer = new StringBuilder();
             if (!string.IsNullOrWhiteSpace(this.Placeholder))
             {
                 buffer.Append($"<option value='0'>{this.Placeholder}</option>");
             }
             string selected = string.Empty;
             if (EnumType != null && EnumType.IsEnum)
             {
                 var enumFields = Enum.GetValues(EnumType);
                 foreach (var enumField in enumFields)
                 {
                     selected = (int)Value == (int)enumField ? "selected='selected'" : "";
                     buffer.Append($"<option value='{(int)enumField}' {selected}>{enumField.ToString()}</option>");
                 }
             }
             output.Content.SetHtmlContent(buffer.ToString());

             return base.ProcessAsync(context, output);
         }
     }

Source版select：

     /// <summary>
     /// Source版Select
     /// </summary>
     [HtmlTargetElement("select-source")]
     public class SelectSourceTagHelper : TagHelper
     {
         public string ValueFieldName { get; set; }
         public string TextFieldName { get; set; }

         public IEnumerable<object> Source { get; set; }
         public object Value { get; set; }
         public string Placeholder { get; set; }
         //public Dictionary<string, object> Attributes { get; set; }
         public override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
         {
             output.TagName = "select";
             StringBuilder buffer = new StringBuilder();
             if (!string.IsNullOrWhiteSpace(this.Placeholder))
             {
                 buffer.Append($"<option value='0'>{this.Placeholder}</option>");
             }
             string selected = string.Empty;
             if (this.Source != null && this.Source.Count() > )
             {
                 Type sourceType = Source.FirstOrDefault().GetType();
                 var tProperty = sourceType.GetProperty(this.TextFieldName, System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.IgnoreCase);
                 var vProperty = sourceType.GetProperty(this.ValueFieldName, System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.IgnoreCase);
                 if (tProperty != null && vProperty != null)
                 {
                     object text = null;
                     object value = null;
                     foreach (var item in Source)
                     {
                         text = tProperty.GetValue(item, null);
                         value = vProperty.GetValue(item, null);

                         selected = (int)this.Value == (int)value ? "selected='selected'" : "";
                         buffer.Append($"<option value='{(int)value}' {selected}>{text}</option>");
                     }
                     output.Content.SetHtmlContent(buffer.ToString());
                 }
             }

             return base.ProcessAsync(context, output);
         }
     }

 @using MVCCoreDemo
 @addTagHelper *,MVCCoreDemo
 @{
     List<Person> personList = new List<Person> {
     new Person{ ID=,Name="zhao"},
     new Person{ ID=,Name="qian"},
     new Person{ ID=,Name="sun"},
     new Person{ ID=,Name="li"}
     };

 }

 <label-input field-name="UserName" label="用户名：" placeholder="请输入用户名" value="zhangsan"></label-input>
 <select-enum id="select1" name="select1" class="c1" enum-type="@typeof(ECustomerLevel)" Value="" placeholder="请选择"></select-enum>
 <select-source id="select2" name="select2" class="c1" source="@personList" Value="" value-field-name="ID" text-field-name="Name" placeholder="请选择"></select-source>