通过JSON将复杂对象发布到MVC Web API

Question

I know this is possible because I do it all the time with other API's. The issue that I am having is that my related sub-object ICollection comes in null when I post the below JSON. Any help would be greatly appreciate as to what I am doing wrong. Here are my objects:

public class PartsExpressOrder
{
    [Key]
    public int OrderId { get; set; }
    public int CustomerId { get; set; }
    public DateTime? OrderDate { get; set; }
    public double SubTotal { get; set; }
    public double Freight { get; set; }
    public double Taxes { get; set; }
    public double Total { get; set; }
    public string OrderStatus { get; set; }
    public string CompanyName { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Phone { get; set; }
    public string Email { get; set; }
    public string ShipToName { get; set; }
    public string ShipToAddress { get; set; }
    public string ShipToCity { get; set; }
    public string ShipToState { get; set; }
    public string ShipToZip { get; set; }
    public string ShipToPhone { get; set; }
    public string BillToName { get; set; }
    public string BillToAddress { get; set; }
    public string BillToCity { get; set; }
    public string BillToState { get; set; }
    public string BillToZip { get; set; }

    public virtual ICollection<PartsExpressOrderItem> PartsExpressOrderItems { get; set; }
}

public class PartsExpressOrderItem
{
    [Key]
    public int OrderItemId { get; set; }
    public int OrderId { get; set; }
    public int MasterPartId { get; set; }
    public string Description { get; set; }
    public int Quantity { get; set; }
    public double Price { get; set; }
    public double Total { get; set; }
}

Here is what I am posting via JSON:

{
  "CustomerId": 1,
  "OrderDate": "2018-07-01",
  "SubTotal": 65.68,
  "Freight": 15.00,
  "Taxes": 5.00,
  "Total": 85.68,
  "OrderStatus": "Sent",
  "CompanyName": "Test Company A",
  "FirstName": "Bob",
  "LastName": "Dobalina",
  "Phone": "5035551212",
  "Email": "bdobalina@testcompanya.com",
  "ShipToName": "Bob Dobalina",
  "ShipToAddress": "5512 Test Company A Blvd. Suite 503",
  "ShipToCity": "Seattle",
  "ShipToState": "WA",
  "ShipToZip": "98103",
  "ShipToPhone": "5035551212",
  "BillToName": null,
  "BillToAddress": null,
  "BillToCity": null,
  "BillToState": null,
  "BillToZip": null,
"PartsExpressOrderItem":
[{
  "MasterPartId": 1,
  "Description": "Widget",
  "Quantity": 2,
  "Price": 20.34,
  "Total": 40.68
},
{
  "MasterPartId": 2,
  "Description": "Sprocket",
  "Quantity": 5,
  "Price": 5.00,
  "Total": 25.00
}]
}

Lastly here is my controller:

 // POST: api/PartsExpressOrders
    [ResponseType(typeof(PartsExpressOrder))]
    public IHttpActionResult PostPartsExpressOrder(PartsExpressOrder partsExpressOrder)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        db.PartsExpressOrder.Add(partsExpressOrder);
        db.SaveChanges();

        foreach(var item in partsExpressOrder.PartsExpressOrderItems)
        {
            item.OrderId = partsExpressOrder.OrderId;
            db.PartsExpressOrderItem.Add(item);
            db.SaveChanges();
        }

        return CreatedAtRoute("DefaultApi", new { id = partsExpressOrder.OrderId }, partsExpressOrder);
    }

Answer 1

It looks like the json representation you have for your ICollection<PartsExpressOrderItem> PartsExpressOrderItems isn't valid. It should look something like:

"PartsExpressOrderItems" : [
    { 
        "MasterPartId": 2,
        "Description": "Sprocket",
        "Quantity": 5,
         "Price": 5.00,
         "Total": 25.00
    },
    { 
        "MasterPartId": 3,
        "Description": "Something",
        "Quantity": 10,
         "Price": 12.00,
         "Total": 47.00
    }
]

The names between json representation and C# need to match unless you have a custom serialization scheme implemented (ie: needed to use PartsExpressOrderItems as the key instead of PartsExpressOrderItem ). Also, you're C# property you're looking at is an ICollection so you need to utilize a json array instead of putting in multiple objects with the same key