Question

how can i have this model in the view

public class PostDetailsViewModel
{
    public Post Posts1 { get; set; }
    public IEnumerable<Post> Posts2 { get; set; }
}

view

@model IEnumerable<forum3.ViewModels.PostDetailsViewModel>
@foreach (var item in Model)
{
   <span>@item.Posts1.Title</span><br />  
   <p>@item.Posts1.Question</p><br /><br />   
}   

controller

  public ViewResult PostDetails(int id)
    {
        PostDetailsViewModel postdetailsviewmodel = new PostDetailsViewModel();
        postdetailsviewmodel.Posts1 = postRepository.Find(id);
        postdetailsviewmodel.Posts2 = postRepository.FindPostByParentIds(id);
        List<PostDetailsViewModel> postDetailsList = new List<PostDetailsViewModel>();
        postDetailsList.Add(postdetailsviewmodel);
        return View(postDetailsList);
    }

how can i have post2 in the view which are the answers

Answer 1

Assuming you want to show a list of questions and its answers and have your View model like this.

( I changed Post1 to Question and Posts2 to Answers for better readability)

public class PostDetailsViewModel
{
    public Post Question { get; set; }
    public List<Post> Answers { get; set; }
}
public class Post
{
    public int ID { set; get; }
    public string Title { set; get; }
}

Assuming your controller returns a List of PostDetailsViewModel and PostDetailsViewModel has a Question Property of Type Post and Answers Property of type List

public ActionResult Posts()
{
  List<PostDetailsViewModel> objVMLsit = new List<PostDetailsViewModel>();
  //add the object to objVMList here   

  return View(objVMLsit);
}

This View will give you the output

@model List<MvcApplication1.Models.PostDetailsViewModel>
@foreach (var item in Model)
{
  <h2>@item.Question.Title</h2><br />  
  foreach (var answer in item.Answers)
  {
        <p>@answer.Title</p>
  }   
}

EDIT : After seeing your controller action method, i guess you want to show a specific post ( Question ) and its answers. So Just return one PostViewModel object from the action to your view instead of returning a List of them

public ViewResult PostDetails(int id)
{
    PostDetailsViewModel postdetailsviewmodel = new PostDetailsViewModel();
    postdetailsviewmodel.Question= postRepository.Find(id);
    postdetailsviewmodel.Answers= postRepository.FindPostByParentIds(id);
    return View(postdetailsviewmodel);
}

And change your View like this

@model MvcApplication1.Models.PostDetailsViewModel
<h2>@Model.Question.Title</h2><br />  
@foreach (var answer in Model.Answers)
{
   <p>@answer.Title</p>
}