asp.net mvc - How to set default value to select list in MVC during run time -

i have view in loop through model , display details in editable mode. 1 of model value select list below

@if (model != null)     {     (int = 0; < model.provider_service_dtls.count; i++)      {     <tr>     <td> @html.dropdownlistfor(m => m.provider_service_dtls[i].activity_code_type,  (selectlist)@viewbag.activity_code_type, "--- select activity code type ---", new { @class = "m-wrap" })</td>     <td>@html.textboxfor(m => m.provider_service_dtls[i].activity_name)</td>         </tr>      }     }  

here viewbag.activity_code_type contain values internal & standard when submitting if user selected internal value 1 pass controller , if standard 2 , here default value "--- select activity code type ---"

now when open same request in edit mode if model value provider_service_dtls[i].activity_code_type 1 select list should default select internal , standard if 2.

i coded this

    @html.dropdownlistfor(m => m.provider_service_dtls[i].activity_code_type,  (selectlist)@viewbag.activity_code_type, model.provider_service_dtls[i].activity_code_type) 

but not working expected giving result below picture

here should default selected internal. change achieve same?

edited

model

public partial class provider_service_dtls     {         [key]         [databasegenerated(databasegeneratedoption.identity)]         public long service_id { get; set; }          public long preapproval_id { get; set; }          public string activity_code_type { get; set; }         public string activity_type { get; set; }          public string activity_type_name { get; set; }           public string activity_code { get; set; }         public string activity_name { get; set; }         public string internal_activity_code { get; set; }         public string internal_activity_name { get; set; }           [foreignkey("preapproval_id"), inverseproperty("provider_service_dtls")]         public virtual provider_preapproval preapproval { get; set; }       } 

editor template

@model provider.models.provider_preapproval @html.dropdownlistfor(m => m.activity_code_type, (selectlist)viewdata["options"]) 

view

inside loop coded this

  @html.editorfor(m => m.provider_service_dtls, new { options = (selectlist)@viewbag.activity_code_type }) 

i getting error

'system.web.mvc.htmlhelper' not contain definition 'editorfor' , best extension method overload 'system.web.mvc.html.editorextensions.editorfor(system.web.mvc.htmlhelper, system.linq.expressions.expression>, string, object)' has invalid arguments

unfortunately @html.dropdownlistfor() behaves little differently other helpers when rendering controls in loop. has been reported issue on codeplex (not sure if bug or limitation)

create custom editortemplate type in collection.

in /views/shared/editortemplates/provider_service_dtls.cshtml (note name must match name of type)

@model yourassembly.provider_service_dtls  @html.hiddenfor(m => m.service_id) @html.dropdownlistfor(m => m.activity_code_type, (selectlist)viewdata["options"], "--- select activity code type ---") .... // html helpers other properties of provider_service_dtls 

and in main view, pass selectlist editortemplate additionalviewdata

@model yourassembly.provider_preapproval   @using (html.beginform()) {   .... // html helpers other properties of provider_preapproval    @html.editorfor(m => m.provider_service_dtls, new { options = (selectlist)@viewbag.activity_code_type })   ... 

the editorfor() methods accepts ienumerable<t> , generate controls each item in collection

edit

an alternative create new selectlist in each iteration of for loop, need set selected property of selectlist. means viewbag property must ienumerable<t>, not selectlist, example in controller

viewbag.activitycodetypelist = new[] {   new { id = 1, name = "internal" },   new { id = 2, name = "standard" } } 

and in view

for (int = 0; < model.provider_service_dtls.count; i++) {   @html.dropdownlistfor(m => m => m.provider_service_dtls[i].activity_code_type,     new selectlist(viewbag.activitycodetypelist, "id", "name", model.provider_service_dtls[i].activity_code_type),     "--- select activity code type ---") }