How to update an entity in Entity Framework?

Question

When I update this entity I get this error:

My Class for database is different with my class in viewmodel

but I convert it.

Please help me and send me the correct code.

Thanks

My error:

Attaching an entity of type 'DomainModel.Models.Tbl_Images' failed because another entity of the same type already has the same primary key value. This can happen when using the 'Attach' method or setting the state of an entity to 'Unchanged' or 'Modified' if any entities in the graph have conflicting key values. This may be because some entities are new and have not yet received database-generated key values. In this case use the 'Add' method or the 'Added' entity state to track the graph and then set the state of non-new entities to 'Unchanged' or 'Modified' as appropriate

My code:

public bool Update(ImagesEditVM model)
{
        bool result = false;

        try
        {
            DomainModel.Models.Tbl_Images img = new Tbl_Images
            {
                Id = model.Id,
                Code = model.Code,
                Image = model.Image,
                Language = model.Language,
                Title = model.Title
            };

            db.Tbl_Images.Attach(img);
            db.Entry<DomainModel.Models.Tbl_Images>(img).State = EntityState.Modified;
            db.SaveChanges();      

            result = true;
            return result;
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
}

Win · Accepted Answer · 2018-10-02 21:53:50Z

1

One way is to query the image first. Then update the values and explicitly call SaveChanges or SaveChangesAsync.

try
{
    var updatingImage = _db.Tbl_Images.FirstOrDefault(i => i.Id == model.Id);

    if (updatingImage != null)
    {
        // either manually map those values or use auto mapper.
        updatingImage.Code = model.Code;
        updatingImage.Image = model.Image;
        updatingImage.Language = model.Language;
        updatingImage.Title = model.Title;

        _db.Tbl_Images.Update(updatingImage);
        _db.SaveChanges();
    }
    ...
}
catch (Exception ex)
{
    throw new Exception(ex.Message);
}

answered Oct 2, 2018 at 21:53

Win

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1 Comment

Mahdi Anjam Over a year ago

I Changed db.Tbl_Images.Update(updatingImage); to db.Tbl_Images.Attach(updatingImage); db.Entry<DomainModel.Models.Tbl_Images>(updatingImage).State = EntityState.Modified; Work it .THanks

henoc salinas · Accepted Answer · 2018-10-02 22:09:09Z

1

you can try with this:

    public bool Update ( ImagesEditVM model )
    {
        bool result = false;
        try
        {

            var existing = db.Tbl_Images.Find ( model.Id );
            if ( existing == null )
            {
                context.Add ( model );
            }
            else
            {
                db.Entry ( existing ).CurrentValues.SetValues ( model);
            }

            context.SaveChanges ( );


            result = true;
            return result;
        }
        catch ( Exception ex )
        {
            throw new Exception ( ex.Message );
        }
    }

see this Link

answered Oct 2, 2018 at 22:09

henoc salinas

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