Model Binding to a List MVC 4

Question

Is there a pattern to bind an IList of items to the view  I seem to be having issues with the HttpPost  I know Phil Haack wrote a nice article but it is dated and he said they might have a fix with MVC 4

User · Answer

Controller  namespace ListBindingTest Controllers       public class HomeController   Controller                             GET   Home           public ActionResult Index                         List lt String gt  tmp   new List lt String gt                 tmp Add  one                tmp Add  two                tmp Add  Three                return View tmp                       HttpPost          public ActionResult Send IList lt String gt  input                        return View input                             Strongly Typed Index View   model IList lt String gt          Layout   null      lt  DOCTYPE html gt    lt html gt   lt head gt   lt meta name  viewport  content  width device-width    gt   lt title gt Index lt  title gt   lt  head gt   lt body gt       lt div gt       using Html BeginForm  Send    Home    POST                   Html EditorFor x   gt  x           lt br   gt           lt input type  submit  value  Send    gt             lt  div gt   lt  body gt   lt  html gt      Strongly Typed Send View   model IList lt String gt          Layout   null      lt  DOCTYPE html gt    lt html gt   lt head gt   lt meta name  viewport  content  width device-width    gt   lt title gt Send lt  title gt   lt  head gt   lt body gt       lt div gt       foreach var element in  Model                 element          lt br   gt             lt  div gt   lt  body gt   lt  html gt    This is all that you had to do man  change his MyViewModel model to IList

User · Answer

This is how I do it if I need a form displayed for each item  and inputs for various properties   Really depends on what I m trying to do though   ViewModel looks like this   public class MyViewModel      public List lt Person gt  Persons get set       View with BeginForm of course     model MyViewModel    for  int i   0  i  lt  Model Persons Count      i         Html HiddenFor m   gt  m Persons i  PersonId       Html EditorFor m   gt  m Persons i  FirstName        Html EditorFor m   gt  m Persons i  LastName               Action    HttpPost public ViewResult MyViewModel vm          Note that on post back only properties which had inputs available will have values   I e   if Person had a  SSN property  it would not be available in the post action because it wasn t a field in the form   Note that the way MVC s model binding works  it will only look for consecutive ID s   So doing something like this where you conditionally hide an item will cause it to not bind any data after the 5th item  because once it encounters a gap in the IDs  it will stop binding   Even if there were 10 people  you would only get the first 4 on the postback    for  int i   0  i  lt  Model Persons Count      i        if i    4   conditionally hide 5th item           but BUG occurs on postback  all items after 5th will not be bound to the the list        Html HiddenFor m   gt  m Persons i  PersonId         Html EditorFor m   gt  m Persons i  FirstName          Html EditorFor m   gt  m Persons i  LastName

User · Answer

A clean solution could be create a generic class to handle the list  so you don t need to create a different class each time you need it   public class ListModel lt T gt        public List lt T gt  Items   get  set         public ListModel List lt T gt  list            Items   list            and when you return the View you just need to simply do   List lt customClass gt  ListOfCustomClass   new List lt customClass gt       Do as needed    return View new ListModel lt customClass gt  ListOfCustomClass      then define the list in the model    model ListModel lt customClass gt    and ready to go    foreach var element in Model Items        do as needed

[c#] Model Binding to a List MVC 4

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