将数据从模型传递到View模型并返回JSON MVC 5

Question

I need to show nested table and i'm getting data using Ajax.

I tried to return directly from database as JSON but that gave me Circular Exception Reference.

So i created a View Model similar to my model but i can't to figure out how to pass data from it without having to write a lot of code with loops and pass by property

here are the models

public class Inventory
{
    public int Id { get; set; }
    public decimal Name{ get; set; }

    public ICollection<StorageUnit> StorageUnits { get; set; }      
}

public class StorageUnits
{
    public int Id { get; set; }
    public string Name{ get; set; }

    public virtual Inventory Inventory  { get; set; }      
}

public class InventoryViewModel
{
    public int Id { get; set; }
    public string Name{ get; set; }

    public ICollection<StorageUnit> StorageUnits { get; set; }      
}

public class StorageUnitsViewModel
{
    public int Id { get; set; }
    public string Name{ get; set; }

    public virtual Inventory Inventory  { get; set; }      
}

and the controller

    public async  Task<ActionResult> GetInventories()
    {
        var inventories = await db.Inventory
            .Include(i => i.StorageUnits)
            .ToListAsync();

        var inventoryViewList = new List<InventoryViewModel>();

        foreach (var item in inventories)
        {
            inventoryViewList.Add(new InventoryViewModel
            {
                Id = item.Id,        
                Name = item.Name,
                StorageUnit = item.StorageUnit // Gives error missing cast
            });
        }

        return Json(inventoryViewList, JsonRequestBehavior.AllowGet);
    }

Answer 1

Inventory model that Name property is decimal and in InventoryViewModel property Name is string, is it right? you can use this code instead of loops:

var inventoryViewList = inventories.Select(x => new InventoryViewModel()
            {
                Id = x.Id,
                Name = x.Name.ToString(),
                StorageUnits = x.StorageUnits
            }).ToList();

you have a error because your object is null and should change your InventoryViewModel to:

public class InventoryViewModel
    {
        public InventoryViewModel()
        {
            this.StorageUnits = new List<StorageUnit>();
        }
        public int Id { get; set; }
        public string Name { get; set; }

        public ICollection<StorageUnit> StorageUnits { get; set; }
    }

Answer 2

You can use a library - AutoMapper

Like this

        Mapper.Initialize(cfg=>cfg.CreateMap<Inventory, InventoryViewModel>());

        var inventories =
            Mapper.Map<IEnumerable<Inventory>, List<InventoryViewModel>>(repo.GetAll());