ViewModels

We want to have more control over the Orders rest API:

1. We want to make the Order ID automatically set for new rows.
2. We want to validate that the customer id exists.
3. We want to validate that the shipper id exists.

To do that we'll create a View Model and manipulate it.

Adding a view model

We'll add a folder called ViewModels under the MVC root folder and in it we'll add a new item using the ViewModel template and call it OrdersViewModel

using System;
using System.Collections.Generic;
using System.Text;
using Firefly.Box;
using ENV;
using ENV.Web;

namespace MVC.ViewModels
{
    class OrdersViewModel : ViewModel
    {
        public OrdersViewModel()
        {
        }
    }
} 

Register the OrdersViewModel instead of the Orders entity in the Controllers\DataApiController.cs

static DataApiController()
{
    _dataApi.Register(typeof(Northwind.Models.Categories),true);
-   _dataApi.Register(typeof(Northwind.Models.Orders),true);
    _dataApi.Register(typeof(ViewModels.OrdersViewModel));
    _dataApi.Register("orderDetails",typeof(Northwind.Models.Order_Details),true);
    _dataApi.Register(typeof(Northwind.Models.Customers)); 

Set the Orders as the From of the ViewModel

class OrdersViewModel : ViewModel
{
    Northwind.Models.Orders Orders = new Northwind.Models.Orders();
    public OrdersViewModel()
    {
        From = Orders;
    }
} 

Make the ViewModel updatable

class OrdersViewModel : ViewModel
{
    Northwind.Models.Orders Orders = new Northwind.Models.Orders();
    public OrdersViewModel()
    {
        From = Orders;
        AllowUpdate = true;
        AllowInsert = true;
        AllowDelete = true;
    }
} 

• Automatically Generating Order Id on a new row
• Server side Validation made easy
• Controlling which columns are included in the api
• Server Side Expression
• Filtering data on the server
• Server side Relation
• Server Side Validation
• Restricting which columns can be updated in the web api
• Saving and loading Entity Data using JSON

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