cómo crear un HTML Helper para extender TextBoxFor() para agregar estilo CSS?

Question

cómo crear un HTML Helper para extender TextBoxFor() para agregar estilo CSS?

@Html.TextBoxFor(model => model.FirstName, new { @class = "txt" }) 

Answer 1

public static System.Web.Mvc.MvcHtmlString DtxTextBoxFor<TModel, TValue> 
     (this System.Web.Mvc.HtmlHelper<TModel> html, 
     System.Linq.Expressions.Expression<System.Func<TModel, TValue>> expression, 
     System.Collections.Generic.IDictionary<string, object> htmlAttributes = null, bool readOnly = false) 
    { 
     if (htmlAttributes == null) 
     { 
      htmlAttributes = 
       new System.Collections.Generic.Dictionary<string, object>(); 
     } 

     System.Web.Mvc.ModelMetadata oModelMetadata = 
      System.Web.Mvc.ModelMetadata.FromLambdaExpression(expression, html.ViewData); 

     if (oModelMetadata == null) 
     { 
      if (readOnly) 
      { 
       if (htmlAttributes.ContainsKey("readonly") == false) 
       { 
        htmlAttributes.Add("readonly", "read-only"); 
       } 
      } 
     } 
     else 
     { 
      if (htmlAttributes.ContainsKey("placeholder") == false) 
      { 
       string strHtmlFieldName = 
        System.Web.Mvc.ExpressionHelper.GetExpressionText(expression); 

       string strLabelText = 
        oModelMetadata.DisplayName ?? 
        oModelMetadata.PropertyName ?? 
        strHtmlFieldName.Split('.').Last(); 

       if (string.IsNullOrEmpty(strLabelText) == false) 
       { 
        htmlAttributes.Add("placeholder", strLabelText); 
       } 
      } 

      if ((readOnly) || (oModelMetadata.IsReadOnly)) 
      { 
       if (htmlAttributes.ContainsKey("readonly") == false) 
       { 
        htmlAttributes.Add("readonly", "read-only"); 
       } 
      } 
     } 

     htmlAttributes.Add("class", "form-control"); 

     System.Linq.Expressions.MemberExpression oMemberExpression = 
      expression.Body as System.Linq.Expressions.MemberExpression; 

     if (oMemberExpression != null) 
     { 
      System.ComponentModel.DataAnnotations.StringLengthAttribute oStringLengthAttribute = 
       oMemberExpression.Member.GetCustomAttributes 
       (typeof(System.ComponentModel.DataAnnotations.StringLengthAttribute), false) 
       .FirstOrDefault() as System.ComponentModel.DataAnnotations.StringLengthAttribute; 

      if (oStringLengthAttribute != null) 
      { 
       if (htmlAttributes.ContainsKey("maxlength") == false) 
       { 
        htmlAttributes.Add("maxlength", oStringLengthAttribute.MaximumLength); 
       } 
      } 
     } 

     return (html.TextBoxFor(expression, htmlAttributes)); 
    } 

Answer 2

sólo tiene que crear un extension method en HtmlHelper:

public static class MyHtmlHelpers 
{ 
    public static MvcHtmlString MyTextBoxFor<TModel, TProperty>(
     this HtmlHelper<TModel> helper, 
     Expression<Func<TModel, TProperty>> expression) 
    { 
     return helper.TextBoxFor(expression, new { @class = "txt" }); 
    } 
} 

A continuación, en su opinión, se puede utilizar como:

@Html.MyTextBoxFor(model => model.FirstName) 

Nota: No se olvide de la @using espacio de nombres de MyHtmlHelpers si sus puntos de vista.

Answer 3

Basándose en @nemesv answer here es una extensión que admite htmlAttributes con atributos personalizados adicionales.

vb.net:

<Extension()> 
Function MyTextBoxFor(Of TModel, TProperty)(ByVal helper As HtmlHelper(Of TModel), ByVal expression As Expression(Of Func(Of TModel, TProperty)), htmlAttributes As Object) As MvcHtmlString   
    'copy htmlAttributes object to Dictionary 
    Dim dicHtmlAttributes As New Dictionary(Of String, Object) 
    For Each prop in htmlAttributes.GetType().GetProperties() 
     dicHtmlAttributes.Add(prop.Name,prop.GetValue(htmlAttributes)) 
    Next 
    'add custom attribute 
    dicHtmlAttributes.Add("foo","bar") 

    Return helper.TextBoxFor(expression, dicHtmlAttributes) 
End Function 

C#:

public static MvcHtmlString MyTextBoxFor<TModel, TProperty>(
    this HtmlHelper<TModel> helper, 
    Expression<Func<TModel, TProperty>> expression, object htmlAttributes) 
{ 
    //copy htmlAttributes object to Dictionary 
    Dictionary<string, object> dicHtmlAttributes = new Dictionary<string, object>; 
    foreach (var prop in htmlAttributes.GetType().GetProperties()) 
    { 
     dicHtmlAttributes.Add(prop.Name, prop.GetValue(htmlAttributes)); 
    } 
    //add custom attribute 
    dicHtmlAttributes.Add("foo", "bar"); 
    return helper.TextBoxFor(expression, dicHtmlAttributes); 
}