Question

What could be the best preferable way of returning back a modified list grabbed from an Entity Framework to our database.

Question In a simpler form :

How to return a Custom List e.g List of about 100,000 records to the database
these are the modified version of our entities in an offline Thread-safe manner.

The Code :

        var query = From context.Products
                    select p;

        var listQuery = query.ToList();

Edit : Seems that all the attached Lists to Entities will cause Thread-Safety errors.
So we have to make a cloned version of the list, something like List
and after edition insert all the items in a regular time-consuming or a shorthand way,
Any Ideas ?

Sample Steps :

1. Make and fill an Custom List Array of our defined type from an entity DataContext
2. Iterate through the List ( about 100,000 items)
3. Edit the List
4. Finally Return it back to the database

How to pass listQuery to the database ?

Iterating through each of them and find the equivalent entity or record via Entity/Linq and change the item ?? could it be the best idea or do we have any shorthand or best practice doing this ?
Any suggestion or idea ?

Answer 1

First, there is a slight error in your code example. You need to add ‘from p in context.Products’ rather than ‘from context.Products’

If I am understanding correctly, the way i typically edit a list of records is:

            var products = dbContext.Products.ToList(); // Gets As List
            foreach (var product in products)
            {
                // edit the value, EF manages what is changed
                product.someField = "some new value";
            }
            dbContext.SaveChanges(); // Saves All Changes

I prefer to use method syntax. If you prefer to use query syntax, you can replace the first line with:

var products = (from p in products
                select p).ToList();