EntityFramework Core auto generate key id property

asp.net-core, asp.net-core-mvc, c#, data-annotations, entity-framework-core

Solution

You need to change your data annotations for your `ExampleModel` so that it auto generates a unique ID.

ExampleModel

public class ExampleModel
{
    [ScaffoldColumn(false)]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    public string SomeData { get; set; }
}

Problem

Using .Net Core MVC. I need to setup my model so that EntityFrameworkCore will auto generate the ID property. I thought that just adding the `[Key]` annotation would do this, but it doesn't. As a matter of fact, it produces an error when the ID field is left blank, which is always because I'm hiding it from the user. I need it to instead Autogenerate a unique ID for the model every time. How do I go about doing this? My ID property is currently of type `int`. ExampleModel ``` public class ExampleModel { [Key] public int ID { get; set; } public string SomeData { get; set; } } ``` ExampleView ``` @model MyNamespace.Models.ExampleModel <form asp-action="Create" asp-controller="ExampleModel"> @Html.EditorForModel() <input type="submit" name="Submit" value="Create"/> </form> ``` ExampleController ``` public IActionResult Create () { return View(); } public IActionResult Create (ExampleModel model) { if (ModelState.IsValid) { _context.ExampleModels.Add(model); _context.SaveChanges(); return RedirectToAction("Index"); } return View(model); } ```

Original source