Attaching an entity of type 'X' failed because another entity of the same type already has the same primary key value

Question

ErrorMessage :

Attaching an entity of type \'FaridCRMData.Models.Customer\' failed because another entity of the same type already has the same prim

Answer 1

have you tried to mark your entity as modified BEFORE attach it to the context?

like this:

public bool Update(TEntity entity)
{
    var entry = context.Entry(entity);
    if (entry.State == EntityState.Detached || entry.State == EntityState.Modified)
    {
        entry.State = EntityState.Modified; //do it here

        context.Set<TEntity>().Attach(entity); //attach

        context.SaveChanges(); //save it
    }
    return true;
}

Answer 2

I believe you might have invoked Select before the update, By default, DBContext will cache the record when they are fethced (Selected), use "AsNoTracking()" in your select call while fetching record.

Answer 3

Try simple change state for entity wich you trying update and SaveChanges()

public bool Update(TEntity entity)
{

        context.Entry(entity).State = System.Data.EntityState.Modified;
        context.SaveChanges();
        return true;
}

Answer 4

If you are selecting some data in between Update operation (as i was getting problem). Don't use .ToList() or .Find() .... Instead of that use as IQueryable , then use .AsNoTracking()..... Problem solved.

Answer 5

You need to detach the local version first and then do the update process

var localEntity = dbContext.Set<theModel>()
    .Local
    .FirstOrDefault(f => f.Id == theModel.Id);
if (localEntity != null)
{
    dbContext.Entry(localEntity).State = EntityState.Detached;
}
dbContext.Entry(appModel).State = EntityState.Modified;