How can we get list of IDs of last inserted set of rows using C# and EF Core

Question

I have a set of images and I tried to add them into a table (ImageGalleries) using EF Core. The insertion goes well. After the insertion I need IDs (there is an identity column in the table) of inserted records. I tried below post in StackOverflow. But I couldn't get reach.

get ids of inserted rows

public ActionResult Save(IEnumerable<IFormFile> images,RoomGalleryVM vm)
        {
            if (images!= null)
            {
                string fileName = "";
                foreach (var image in images)
                {
                    var fileContent = ContentDispositionHeaderValue.Parse(image.ContentDisposition);
                    fileName = Path.GetFileName(fileContent.FileName.ToString().Trim('"'));
                    var gallery = new RoomGallery()
                    {
                        RoomId = vm.RoomId,
                        Description=fileName,
                        Status="A"
                    };
                    Context.RoomGalleries.Add(gallery);
                }
                Context.SaveChanges();
                //var Ids = vm.Select(c => c.Id).ToList();
            }
            return View("RoomGalleryIndex");
        }

RoomGalleryVM

 public class RoomGallery
    {
        public int Id { get; set; }
        public int RoomId { get; set; }
        public Room Room { get; set; }
        [StringLength(100)] public string Description { get; set; }
        [StringLength(10)] public string Status { get; set; }
    }

Index page

<form method="post" asp-action="Save" asp-controller="RoomGallery">
<h6 style="margin-top: 2em;">Room:</h6>
    @(Html.Kendo().DropDownList()
            .Name("RoomId")
            .HtmlAttributes(new { style = "width:100%" })
            .OptionLabel("Select room...")
            .DataTextField("RoomName")
            .DataValueField("Id")           
            .DataSource(source =>
            {
                source.Read(read =>
                {
                    read.Action("GetRooms", "Reservation");
                })
                .ServerFiltering(true);
            })
            .Enable(false)
            .AutoBind(false)
    )
    <br />    
    <div class="demo-section">
        @(Html.Kendo().Upload()
            .Name("images")
            .HtmlAttributes(new { aria_label = "files" })
        )
        <p style="padding-top: 1em; text-align: right">
            <button>Submit</button>
        </p>
    </div>
</form>

You are creating new instance of gallery and adding it to the dbContext. So the gallery should contain new id. Your vm doesn't reference newly created gallery objects. — SlobodanT, May 21 '22 at 03:50

score 1 · Accepted Answer · answered May 21 '22 at 06:06

Just remember all the gallery you make, and retrieve their Id after you save:

            var newRGs = new List<RoomGallery>();
            foreach (var image in images)
            {
                var fileContent = ContentDispositionHeaderValue.Parse(image.ContentDisposition);
                fileName = Path.GetFileName(fileContent.FileName.ToString().Trim('"'));
                var gallery = new RoomGallery()
                {
                    RoomId = vm.RoomId,
                    Description=fileName,
                    Status="A"
                };
                Context.RoomGalleries.Add(gallery);
                newRGs.Add(gallery);
            }

Then you can get the IDs for whatever you need after you have saved (the value the db calculated will be patched back into the local object)

var ids = newRGs.Select(rg => rg.Id).ToList();

If you want to use them in your view, don't forget to patch them back into your view model (what you want to use them for is unclear to me; the main point of this answer is "if you remember which objects you add to a context before you save then you can enumerate them for any db calculated values after you have saved")

Thank you for your explanation. It helps to understand the way of correcting the issue as suggested by the SolobodanT. — chandrasiri, May 21 '22 at 12:46

score 0 · Answer 2 · answered May 21 '22 at 11:25

Update your code to below,

public ActionResult Save(IEnumerable<IFormFile> images,RoomGalleryVM vm)
    {
        List<int> Ids=new List<int>();
        if (images!= null)
        {
            string fileName = "";
            foreach (var image in images)
            {
                var fileContent = ContentDispositionHeaderValue.Parse(image.ContentDisposition);
                fileName = Path.GetFileName(fileContent.FileName.ToString().Trim('"'));
                var gallery = new RoomGallery()
                {
                    RoomId = vm.RoomId,
                    Description=fileName,
                    Status="A"
                };
                Context.RoomGalleries.Add(gallery);
                Context.SaveChanges();
                Ids.Add(gallery.Id)
            }
        }
        var data = Ids; // here you will get list of ids
        return View("RoomGalleryIndex");
    }

Thank you for your explanation. It helps to understand the way of correcting the issue as suggested by the SolobodanT. — chandrasiri, May 21 '22 at 12:44
There was already a similar answer offering a better performance option than this approach, when you posted this answer. Saving changes upon every pass of the images loop is not ideal — Caius Jard, May 22 '22 at 01:41

How can we get list of IDs of last inserted set of rows using C# and EF Core

2 Answers2