Question

我正在尝试将htmlAttributes添加到现有帮助程序中：

public static MvcHtmlString ExCheckBox (this HtmlHelper helper, string name, bool? value, bool readOnly)
{
  return ExCheckBox(helper, name, value, readOnly, "");
}

public static MvcHtmlString ExCheckBox (this HtmlHelper helper, string name, bool? value, bool readOnly, string Label)
{
  var HTML = ExCheckBox(helper, name, value, readOnly, Label, new Dictionary<string, string>());
  return new MvcHtmlString(HTML.ToString());
}

public static MvcHtmlString ExCheckBox4 (this HtmlHelper helper, string name, bool? value, bool readOnly, string Label, object htmlAttributes)
{
  var HTML = ExCheckBox(helper, name, value, readOnly, Label, new RouteValueDictionary(htmlAttributes), new Dictionary<string, string>());
  return new MvcHtmlString(HTML.ToString());
}

public static MvcHtmlString ExCheckBox (this HtmlHelper helper, string name, object value, bool readOnly, string Label, IDictionary<string, string> Params)
    {
    string HTML = "";
    if (readOnly)
        HTML = String.Format("<label for='{0}'>{1}</label>", name, value == null ? "" : ((bool?)value == true ? "Yes" : "No"));
    else
        {
        string DropDownList = AddEmptyOption(System.Web.Mvc.Html.SelectExtensions.DropDownList(helper, name, GetDropDownListItems(value == null ? "" : value.ToString())).ToString());
        HTML += DropDownList;
        }
    HTML = AddCellsAndLabel(HTML, name, Label, Params);
    return new MvcHtmlString(HTML);
    }

public static List<SelectListItem> GetDropDownListItems (string currentValue)
    {
    var list = new List<SelectListItem>();
    var item = new SelectListItem();

    item.Text = "No";
    item.Value = "false";
    if (currentValue == false.ToString())
        item.Selected = true;
    list.Add(item);
    item = new SelectListItem();
    item.Text = "Yes";
    item.Value = "true";
    if (currentValue == true.ToString())
        item.Selected = true;
    list.Add(item);

    return list;
    }

   private static string AddCellsAndLabel (string ControlHTML, string name, string Label, IDictionary<string, string> Params)
            {
            if (!String.IsNullOrEmpty(Label))
                {
                string ControlColSpan = "";
                string LabelColSpan = "";
                if (Params.ContainsKey(HtmlHelperParams.ControlColSpan))
                    {
                    ControlColSpan = "colspan='" + Params[HtmlHelperParams.ControlColSpan] + "'";
                    }
                if (Params.ContainsKey(HtmlHelperParams.LabelColSpan))
                    {
                    LabelColSpan = "colspan='" + Params[HtmlHelperParams.LabelColSpan] + "'";
                    }
                ControlHTML = String.Format("<td " + LabelColSpan + "  class=\"Label\"><label for=\"{0}\">{1}</label></td>", name, Label) + "<td " + ControlColSpan + " class=\"ControlCell\">" + ControlHTML + "</td>";
                }
            return ControlHTML;
            }

前两个助手工作得很好，第三个ExCheckBox4我得到了这个错误：

没有超载方法＆＃39; ExCheckBox＆＃39;需要7个参数

感谢您的建议。

Answer 1

您的代码存在许多问题，包括

没有强烈打字
您覆盖控件名称属性，因此它不会绑定到您的回帖后的模特
你在表格中使用它，假设这是在for中呈现的循环，您的渲染重复id（无效的HTML）和name 属性（不会在回发后绑定到你的收藏）。
您的呈现<label>元素只读它但不是与控件相关联（语义不正确）。
您的扩展程序接受值为object的值，但会抛出如果不是nullable bool

尝试以下

public static MvcHtmlString XCheckBox<TModel>(this HtmlHelper<TModel> helper, Expression<Func<TModel, bool?>> expression, bool isReadOnly, int labelColumns, int controlColumns, object htmlAttributes)
{
  ModelMetadata metaData = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);
  string label = metaData.GetDisplayName();
  string name = ExpressionHelper.GetExpressionText(expression);
  StringBuilder html = new StringBuilder();      
  if (isReadOnly)
  {
    html.Append(ReadonlyLabelCell(label, labelColumns));
    html.Append(ReadonlyValueCell((bool?)metaData.Model, controlColumns));
  }
  else
  {
    html.Append(LabelCell(label, name, labelColumns));
    html.Append(ControlCell(name, (bool?)metaData.Model, controlColumns, htmlAttributes));
  }     
  return MvcHtmlString.Create(html.ToString());
}

private static string ReadonlyLabelCell(string label, int colSpan)
{
  TagBuilder span = new TagBuilder("span");
  span.InnerHtml = label;
  TagBuilder cell = new TagBuilder("td");
  cell.AddCssClass("label");
  cell.MergeAttribute("colspan", colSpan.ToString());
  cell.InnerHtml = span.ToString();
  return cell.ToString();
}

private static string ReadonlyValueCell(bool? value, int colSpan)
{
  TagBuilder span = new TagBuilder("span");
  span.InnerHtml = value.HasValue ? value.Value ? "Yes" : "No" : "Not set";
  TagBuilder cell = new TagBuilder("td");
  cell.AddCssClass("readonly"); // added class for styling
  cell.MergeAttribute("colspan", colSpan.ToString());
  cell.InnerHtml = span.ToString();
  return cell.ToString();
}

private static string LabelCell(string labelText, string controlName, int colSpan)
{
  TagBuilder label = new TagBuilder("label");
  label.MergeAttribute("for", controlName);
  label.InnerHtml = labelText;
  TagBuilder cell = new TagBuilder("td");
  cell.AddCssClass("label");
  cell.MergeAttribute("colspan", colSpan.ToString());
  cell.InnerHtml = label.ToString();
  return cell.ToString();
}

private static string ControlCell(string controlName, bool? value, int colSpan, object htmlAttributes)
{
  StringBuilder html = new StringBuilder();
  TagBuilder option = new TagBuilder("option");
  option.MergeAttribute("value", string.Empty);
  option.InnerHtml = "Not set";
  html.Append(option.ToString());
  option = new TagBuilder("option");
  option.MergeAttribute("value", "true");
  if (value.HasValue && value.Value)
  {
    option.MergeAttribute("selected", "selected");
  }
  option.InnerHtml = "Yes";
  html.Append(option.ToString());
  option = new TagBuilder("option");
  option.MergeAttribute("value", "false");
  if (value.HasValue && !value.Value)
  {
    option.MergeAttribute("selected", "selected");
  }
  option.InnerHtml = "No";
  html.Append(option.ToString());
  TagBuilder select = new TagBuilder("select");
  select.MergeAttribute("name", controlName);
  select.MergeAttribute("id", HtmlHelper.GenerateIdFromName(controlName));
  select.MergeAttributes(HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
  select.InnerHtml = html.ToString();
  TagBuilder cell = new TagBuilder("td");
  cell.AddCssClass("controlcell");
  cell.MergeAttribute("colspan", colSpan.ToString());
  cell.InnerHtml = select.ToString();
  return cell.ToString();
}

然后是其他重载

public static MvcHtmlString XCheckBox<TModel>(this HtmlHelper<TModel> helper, Expression<Func<TModel, bool?>> expression, bool isReadOnly)
{
  return XCheckBox(helper, expression, isReadOnly, 1, 1, null);
}

等

使用如下

@Html.XCheckBoxFor(m => m.Client.Rotates, false, 1, 1, new { @class = "form-control" })

Answer 2

很明显没有接受此参数的方法（在ExCheckBox4正文中）

var HTML = ExCheckBox(helper, name, value, readOnly, Label, new RouteValueDictionary(htmlAttributes), new Dictionary<string, string>());

Answer 3

您可能需要将其更改为

public static MvcHtmlString ExCheckBox4 (this HtmlHelper helper, string name, bool? value, bool readOnly, string Label, object htmlAttributes)
{
 var HTML = helper.ExCheckBox(name, value, readOnly, Label, new RouteValueDictionary(htmlAttributes));
 return new MvcHtmlString(HTML.ToString());
}

MVC5帮助器htmlAttributes

3 个答案: