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 == 0 || !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() > 0)
            {
                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=1,Name="zhao"},
    new Person{ ID=2,Name="qian"},
    new Person{ ID=3,Name="sun"},
    new Person{ ID=4,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="3" placeholder="请选择"></select-enum>
<select-source id="select2" name="select2" class="c1" source="@personList" Value="3" value-field-name="ID" text-field-name="Name" placeholder="请选择"></select-source>