发表新帖
发表新帖

How do you create a dropdownlist from an enum in ASP.NET MVC?

后端 未结
关注
30 1948
不知归路
不知归路 2020-11-21 16:36

I\'m trying to use the Html.DropDownList extension method but can\'t figure out how to use it with an enumeration.

Let\'s say I have an enumeration like

30条回答
  • 梦谈多话
    梦谈多话 (楼主)
    2020-11-21 16:54

    Building on Simon's answer, a similar approach is to get the Enum values to display from a Resource file, instead of in a description attribute within the Enum itself. This is helpful if your site needs to be rendered in more than one language and if you were to have a specific resource file for Enums, you could go one step further and have just Enum values, in your Enum and reference them from the extension by a convention such as [EnumName]_[EnumValue] - ultimately less typing!

    The extension then looks like:

    public static IHtmlString EnumDropDownListFor(this HtmlHelper html, Expression> expression)
{            
    var metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData);

    var enumType = Nullable.GetUnderlyingType(metadata.ModelType) ?? metadata.ModelType;

    var enumValues = Enum.GetValues(enumType).Cast();

    var items = from enumValue in enumValues                        
                select new SelectListItem
                {
                    Text = GetResourceValueForEnumValue(enumValue),
                    Value = ((int)enumValue).ToString(),
                    Selected = enumValue.Equals(metadata.Model)
                };


    return html.DropDownListFor(expression, items, string.Empty, null);
}

private static string GetResourceValueForEnumValue(TEnum enumValue)
{
    var key = string.Format("{0}_{1}", enumValue.GetType().Name, enumValue);

    return Enums.ResourceManager.GetString(key) ?? enumValue.ToString();
}



    Resources in the Enums.Resx file looking like
ItemTypes_Movie : Film
    


    One other thing I like to do is, instead of calling the extension method directly, I'd rather call it with a @Html.EditorFor(x => x.MyProperty), or ideally just have the whole form, in one neat @Html.EditorForModel(). To do this I change the string template to look like this
    


    @using MVCProject.Extensions

@{
    var type = Nullable.GetUnderlyingType(ViewData.ModelMetadata.ModelType) ?? ViewData.ModelMetadata.ModelType;

    @(typeof (Enum).IsAssignableFrom(type) ? Html.EnumDropDownListFor(x => x) : Html.TextBoxFor(x => x))
}

    


    If this interests you, I've put a much more detailed answer here on my blog:
    


    http://paulthecyclist.com/2013/05/24/enum-dropdown/
    
    
    
             
    
                                                        
    
            
            
    
              
                
                0
              
                   
                
               讨论(0)
              
                                                  
              
              
    
                          
             
       
          
              
    
                                       
    

    

                
    
                         
          
                              			
        
        
        
    
          
    
            
            
    
              
              
    
            
    


                                 
              
    
            
    
                          
    

        
         
    
                
                
    
                  
                
    
                
    
                   看不清?
                
    
              
    
                                  
    
                    
   
                 
             
              
    提交回复
    
            
    
          
    
        
    
      
       
      
    
    
    
          
 
     
 
    
        
    热议问题