保存或接受更改失败，因为多个类型的实体具有相同的主键值

Question

I use repository pattern in asp.net mvc 5, I select the data from table and then add one entity in this data with value and I want to set this data in database with added entity value but Saving or accepting changes failed because more than one entity of type 'BlogPost.DAL.Entity.BlogPost.Blog' have the same primary key value error is occured but in database this row is inserted what I need to do avoid this error.

model = await _IBlogSerices.BlogGetByID(Id);
Blog data = _db.Blog.Find(Id);
_db.Blog.Remove(data);
_db.SaveChanges();
model.IsPublish = true;
await _IBlogSerices.CreateBlog(model);
return View();

Answer 1

it seem there is not problem if you BlogGetByID(Id) function like

public Task<Blog> BlogGetByID(int id){
  return _db.Blog.FirstOrDefaultAsync(p => p.Id ==id);
}