Insert rows using Linq

Question

Can anyone tell where I make a mistake ? :( I want to insert a row using this. It's just not working. I also tried to use "context.SaveChanges();" but nothing changed. No insert at all, and no exception.

public List<string> Add_Address(string address, int selected_item)
        {
            List<string> list = new List<string>();

            using(var context = new RSS_Reader_Database())
            {
                Address Address = new Address();
                Category_Address Category_Address = new Category_Address();

                Address.URL = address.ToString();                               

                int max_id = Convert.ToInt32(context.Addresses.OrderByDescending(t => t.ID_Address).FirstOrDefault());

                Category_Address.ID_Address = max_id;                
                Category_Address.ID_Category = selected_item+1;


                var select_query = from t in context.Addresses select t.URL;


                foreach (var element in select_query)
                {
                    list.Add(element);
                }

            }            

            return list;
}

Edit: Following all Your advices, I made something that works. Looking at this code above, I have no idea what I was trying to do yesterday. Thanks a lot.

public List<string> Add_Address(string address, int selected_item)
        {
            List<string> list = new List<string>();

            using(var context = new RSS_Reader_Database())
            {
                Address Address = new Address() { URL = address };                

                context.Addresses.Add(Address);
                context.SaveChanges();

                int max_id = context.Addresses.Max(u => u.ID_Address);

                Category_Address Category_Address = new Category_Address() { ID_Address = max_id, ID_Category = selected_item + 1 };

                context.Categories_Addresses.Add(Category_Address);
                context.SaveChanges();

                var query = from t in context.Addresses
                            select t.URL;

                var data = query.ToList();

                foreach (var element in data)
                {
                    list.Add(element);   
                }               

            }            

            return list;

        }

You set a property in an object, but you didn't do anything with the object. — SLaks
– SLaks, Commented Oct 27, 2015 at 21:39

Bradford Dillon · Accepted Answer · 2015-10-28 01:01:32Z

1

Saving with Entity Framework generally works like this. Using your above code as a starting point.

using(var context = new RSS_Reader_Database())
{
    Address address = new Address();

    // Set address properties

    context.Addresses.Add(address);
    context.SaveChanges();
 }

You need to add the object to the DbSet<T> where T is the type of the entity that is defined on the DbContext. You then need to call SaveChanges() on the context.

I would suggest reading this. It is an easy to follow introduction to Entity Framework.

edited Oct 28, 2015 at 1:01

answered Oct 28, 2015 at 0:53

Bradford Dillon

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Lair Jr · Accepted Answer · 2015-10-27 21:48:35Z

1

Not sure exactly what you are trying to do.

But if you are expecting to insert the data by the list.Add(element); command it won't work.

If you are planning to insert data into the same DB, you need to use one property from the context to represent the List collection add a new element on this property.

Something like:

context.Lists.Add(element);

answered Oct 27, 2015 at 21:48

Lair Jr

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user2989845 · Accepted Answer · 2015-10-27 21:44:44Z

0

if you want retrieve data, you should not call SaveChanges() !,

try get all values from one query like this:

            List<string> select_query = (from t in context.Addresses select t.URL).ToList();

answered Oct 27, 2015 at 21:44

user2989845

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