ARK Posts - Answer Overflow

ARK

•Created by ARK on 2/7/2024 in #help

Display many-to-many table data using view model in controller in ASP.NET Core MVC

I want to display many-to-many table data using a view model in controller but I get this error:

CS0029: Cannot implicitly convert type 'Website.Model.PostModel' to 'System.Collections.GenericList<Website.Model.PostModel>'

Model:

c#
public class PostModel
{
    [Key]
    public int Id { get; set; }

    public List<TagsModel> Tags { get; set; } = new List<TagsModel>();

    public virtual List<PostTagModel> PostTags { get; set; } = new List<PostTagModel>();
}

public class TagsModel
{        
    [Key]
    public int Id { get; set; }

    public List<PostModel> Posts { get; set; }
    public virtual List<PostTagModel> PostTags { get; set; }
}

public class PostTagModel
{
    public int PostId { get; set; }
    public int TagId { get; set; }

    public virtual PostModel Post { get; set; }
    public virtual TagsModel Tag { get; set; }
}

c#
public class PostModel
{
    [Key]
    public int Id { get; set; }

    public List<TagsModel> Tags { get; set; } = new List<TagsModel>();

    public virtual List<PostTagModel> PostTags { get; set; } = new List<PostTagModel>();
}

public class TagsModel
{        
    [Key]
    public int Id { get; set; }

    public List<PostModel> Posts { get; set; }
    public virtual List<PostTagModel> PostTags { get; set; }
}

public class PostTagModel
{
    public int PostId { get; set; }
    public int TagId { get; set; }

    public virtual PostModel Post { get; set; }
    public virtual TagsModel Tag { get; set; }
}

ViewModel:

c#
public class CardsViewModel
{
    public List<PostModel>? PostCard { get; set; }
}

c#
public class CardsViewModel
{
    public List<PostModel>? PostCard { get; set; }
}

Controller:

c#
[HttpGet]
public async Task<IActionResult> Detail(int id)
{
    var TaggedPostVM = new CardsViewModel
    {
        PostCard = await _context.Posts.Include(t => t.PostTags) 
                                    .ThenInclude(p => p.Post)
                                    .SingleAsync(t => t.Id == id);
    };

    return View(TaggedPostVM);
}

c#
[HttpGet]
public async Task<IActionResult> Detail(int id)
{
    var TaggedPostVM = new CardsViewModel
    {
        PostCard = await _context.Posts.Include(t => t.PostTags) 
                                    .ThenInclude(p => p.Post)
                                    .SingleAsync(t => t.Id == id);
    };

    return View(TaggedPostVM);
}

View:

@using RecipeWebsite.ViewModels.CardsViewModel

@model CardsViewModel

@foreach (var item in Model.PostCard)
{
   <!-- HTML -->
}

@using RecipeWebsite.ViewModels.CardsViewModel

@model CardsViewModel

@foreach (var item in Model.PostCard)
{
   <!-- HTML -->
}

When the controller is used without view model, it works without error. Example:

c#
[HttpGet]
public async Task<IActionResult> Detail(int id)
{
    var Tag = await _context.Posts
                            .Include(t => t.PostTags) 
                            .ThenInclude(p => p.Post)
                            .SingleAsync(t => t.Id == id);

    return View(Tag);
}

c#
[HttpGet]
public async Task<IActionResult> Detail(int id)
{
    var Tag = await _context.Posts
                            .Include(t => t.PostTags) 
                            .ThenInclude(p => p.Post)
                            .SingleAsync(t => t.Id == id);

    return View(Tag);
}

11 replies

Gaming

Programming