<!--標(biāo)簽助手版form-->
<form asp-controller="Home" asp-action="Index" class="form-horizontal" method="post">

</form>
<!--Html幫助類版form-->
@using (Html.BeginForm("Index", "Home", FormMethod.Post,, new { Class = "form-horizontal" }))
{

}

public class SignUpViewModel
 {
 [Required]
 [Display(Name ="用戶名")]
 [MaxLength(30,ErrorMessage = "用戶名不能超過30")]
 public string UserName { get; set; }

 [Required]
 [DataType(DataType.Password)]
 [RegularExpression(@"((?=.*\d)(?=.*\D)|(?=.*[a-zA-Z])(?=.*[^a-zA-Z]))^$",ErrorMessage ="密碼至少包含兩種以上字符")]
 [Display(Name ="密碼")]
 public string Password { get; set; }

 [DataType(DataType.MultilineText)]
 public string Description { get; set; }
 }

<form asp-controller="Home" asp-action="SignUp" method="post" class="form-horizontal">
 <div class="form-group">
 <label asp-for="UserName"></label>
 <input asp-for="UserName" />
 <span asp-validation-for="UserName"></span>
 </div>
 <div class="form-group">
 @Html.LabelFor(m=>m.Password)
 @Html.PasswordFor(m=>m.Password)
 @Html.ValidationMessageFor(m=>m.Password)
 </div>
 <div class="form-group">
 <label asp-for="Description"></label>
 <textarea asp-for="Description"></textarea>
 <span asp-validation-for="Description"></span>
 </div>
 <div class="form-group">
 <input type="submit" value="提交" />
 <input type="reset" value="重置" />
 </div>
</form>

public IActionResult SignUp(SignUpViewModel model)
 {
 if (ModelState.IsValid)
 {
 return RedirectToAction("Index");
 }
 else
 {
 return RedirectToAction("Index",model);
 }
 }

protected IHtmlGenerator Generator { get; }

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

 /// <summary>
 /// An expression to be evaluated against the current model.
 /// </summary>
 [HtmlAttributeName(ForAttributeName)]
public ModelExpression For { get; set; }

//自定義標(biāo)簽助手名為bg-form
 [HtmlTargetElement("bg-form")]
 public class FormTagHelper : TagHelper
 {
 [ViewContext]
 [HtmlAttributeNotBound]
 public ViewContext ViewContext { get; set; }

 [HtmlAttributeName("asp-for")]
 public ModelExpression For { get; set; }

 protected IHtmlGenerator Generator { get; }

 public FormTagHelper(IHtmlGenerator generator)
 {
 Generator = generator;
 }

 [HtmlAttributeName("asp-controller")]
 public string Controller { get; set; }

 [HtmlAttributeName("asp-action")]
 public string Action { get; set; }

 //異步方法
 public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
 {
 output.TagName = "form";
 if (!string.IsNullOrWhiteSpace(Controller))
 {
 output.Attributes.Add("action", "/" + Controller + "/" + Action);
 }

 output.Attributes.Add("class", "form-horizontal");

 //獲取子屬性
 var props = For.ModelExplorer.Properties;
 foreach (var prop in props)
 {
 //生成表單
 var div = new TagBuilder("div");
 div.AddCssClass("form-group");
 var label = Generator.GenerateLabel(ViewContext, prop, null, prop.Metadata.DisplayName, null);
 var input = Generator.GenerateTextBox(ViewContext, prop, prop.Metadata.PropertyName, null, null, null);
 var span = Generator.GenerateValidationMessage(ViewContext, prop, prop.Metadata.PropertyName, null, ViewContext.ValidationMessageElement, null);
 div.InnerHtml.AppendHtml(label);
 div.InnerHtml.AppendHtml(input);
 div.InnerHtml.AppendHtml(span);
 output.Content.AppendHtml(div);
 }
 //添加按鈕
 var btn = new TagBuilder("div");
 btn.AddCssClass("form-group");
 var submit = new TagBuilder("input");
 submit.Attributes.Add("type", "submit");
 submit.Attributes.Add("value", "提交");
 var reset = new TagBuilder("input");
 reset.Attributes.Add("type", "reset");
 reset.Attributes.Add("value", "重置");
 btn.InnerHtml.AppendHtml(submit);
 btn.InnerHtml.AppendHtml(reset);
 output.Content.AppendHtml(btn);
 //將原有的內(nèi)容添加到標(biāo)簽內(nèi)部
 output.Content.AppendHtml(await output.GetChildContentAsync());

 }
 }

<bg-form asp-controller="Home" asp-action="SignUp" asp-for="@Model">
</bg-form>