Can I return the 'id' field after a LINQ insert?

Question

When I enter an object into the DB with Linq-to-SQL can I get the id that I just inserted without making another db call? I am assuming this is pretty easy, I just don't know how.

Thank you.

Answer 1

After you commit your object into the db the object receives a value in it's ID field. So:

myObject.Field1 = "value";

// Db is the datacontext
db.MyObjects.InsertOnSubmit(myObject);
db.SubmitChanges();

// You can retrieve the id from the object
int id = myObject.ID;

Answer 2

When inserting the generated ID is saved into the instance of the object being saved (see below):

protected void btnInsertProductCategory_Click(object sender, EventArgs e)
{
  ProductCategory productCategory = new ProductCategory();
  productCategory.Name = “Sample Category”;
  productCategory.ModifiedDate = DateTime.Now;
  productCategory.rowguid = Guid.NewGuid();
  int id = InsertProductCategory(productCategory);
  lblResult.Text = id.ToString();
}

//Insert a new product category and return the generated ID (identity value)
private int InsertProductCategory(ProductCategory productCategory)
{
  ctx.ProductCategories.InsertOnSubmit(productCategory);
  ctx.SubmitChanges();
  return productCategory.ProductCategoryID;
}

reference: http://blog.jemm.net/articles/databases/how-to-common-data-patterns-with-linq-to-sql/#4