使用linq-to-sql更新记录列表

Question

I have a table that has 2 columns: FruitID, FruitSize. I want to write a query that takes in a list of FruitIDs and a FruitSize and that sets the new FruitSize for all the fruits.

This is what I have so far:

public void ChangeFruitSizes(List<long> TheFruitIDs, long NewFruitSize)
{
   using (SomeDC MyDC = new SomeDC())
   {
      var TheFruits = (from f in MyDC.Fruits
                       where TheFruitIDs.Contains(f.FruitID)
                       select f).ToList();

      foreach (Fruits f in TheFruits)
      {
          f.FruitSize = NewFruitSize;
      }

      MyDC.SubmitChanges();

   }
}

It's currently not bugging but the fields in the database aren't updated. Thanks for your suggestions.

Answer 1

To write this in more concise way, you can try ForEach() in list like below:

using (SomeDC MyDC = new SomeDC())
{
    (from f in MyDC.Fruits
               where TheFruitIDs.Contains(f.FruitID)
               select f).ToList().ForEach(F => F.FruitSize = NewFruitSize);

    MyDC.SubmitChanges();

}

Answer 2

Just looking at the code everything is correct. Probably the error is at what is not shown: The model. I suspect you don't have a primary key defined. Define a primary key on the ID field and re-create the model (remove the table from the designer and add it back).