插入记录实体框架

Question

So I was trying to insert a record in a database using entity Framework well I tried this simple code

TestEntities DB = new TestEntities();
List<Article> Articles = BD.Articles.ToList();
Articles.Add(new Article() { Id = 0, Category = "Category1",  Title = "Title1"});
Articles.Add(new Article() { Id = 0, Category = "Category2", Title = "Title2" });
DB.SaveChanges();

The records got added to the Articles list but not to the database can someone please explain to me how does this work.

Answer 1

Articles is just an in-memory copy of the DbSet . You should add the items to the DbSet as well if you want to be able to persist them to the database:

var art = new Article() { Id = 0, Category = "Category1",  Title = "Title1"};
Articles.Add(art);
BD.Articles.Add(art);

The List<Article> is not "connected" to the DbSet , DbContext nor the database in any way.

Answer 2

using(TestEntities DB = new TestEntities())
{
    BD.Articles.Add(new Article() { Id = 0, Category = "Category1",  Title = "Title1"});
    BD.Articles.Add(new Article() { Id = 0, Category = "Category2", Title = "Title2" });
    DB.SaveChanges();
}

1. Add the new article to the DbSet, not the retrieved List which is just an in memory representation.
2. Always wrap your types that implement IDisposable in using statements. In this case it ensures that the db connection is closed when the code exists.