Optimizing simple usage of Linq in C#

Question

I have replicated a stripped-down version of my code that has recently been re-written to use linq to access the database.

However, in my opinion, the linq is really simple and could probably be optimized quite a bit, especially around line 90 where there is a linq statement inside a foreach loop.

It'd be really helpful to see how someone else would go about writing this simple task using linq. Thanks in advance! Below is a snippet of my source code.

    // Model objects - these are to be populated from the database,
// which has identical fields and table names.
public class Element
{
    public Element()
    {
        Translations = new Collection<Translation>();
    }

    public int Id { get; set; }
    public string Name { get; set; }
    public Collection<Translation> Translations { get; set; }

    public class Translation
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string Content { get; set; }
        public Language Lang { get; set; }
    }
}
public class Language
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Code { get; set; }
}

// Stripped-down functions for adding and loading Element
// objects to/from the database:

public static class DatabaseLoader
{
    // Add method isn't too bulky, but I'm sure it could be optimised somewhere.
    public static void Add(string name, Collection<Translation> translations)
    {
        using (var db = DataContextFactory.Create<ElementContext>())
        {
            var dbElement = new Database.Element()
            {
                Name = name
            };
            db.Elements.InsertOnSubmit(dbElement);
            // Must be submit so the dbElement gets it's Id set.
            db.SubmitChanges();

            foreach (var translation in translations)
            {
                db.Translations.InsertOnSubmit(
                    new Database.Translation()
                        {
                            FK_Element_Id = dbElement.Id,
                            FK_Language_Id = translation.Lang.Id,
                            Title = translation.Title,
                            Content = translation.Content
                        });
            }

            // Submit all the changes outside the loop.
            db.SubmitChanges();
        }
    }

    // This method is really bulky, and I'd like to see the many separate linq
    // calls merged into one clever statement if possible (?).
    public static Element Load(int id)
    {
        using (var db = DataContextFactory.Create<ElementContext>())
        {
            // Get the database object of the relavent element.
            var dbElement =
                (from e in db.Elements
                 where e.Id == id
                 select e).Single();

            // Find all the translations for the current element.
            var dbTranslations =
                from t in db.Translations
                where t.Fk_Element_Id == id
                select t;

            // This object will be used to buld the model object.
            var trans = new Collection<Translation>();

            foreach (var translation in dbTranslations)
            {
                // Build up the 'trans' variable for passing to model object.
                // Here there is a linq statement for EVERY itteration of the
                // foreach loop... not good (?).
                var dbLanguage =
                    (from l in db.Languages
                     where l.Id == translation.FK_Language_Id
                     select l).Single();

                trans.Add(new Translation()
                    {
                        Id = translation.Id,
                        Title = translation.Title,
                        Content = translation.Content,
                        Language = new Language()
                            {
                                Id = dbLanguage.Id,
                                Name = dbLanguage.Name, 
                                Code = dbLanguage.Code
                            }
                    });
            }

            // The model object is now build up from the database (finally).
            return new Element()
                {
                    Id = id,
                    Name = dbElement.Name,
                    Translations = trans
                };
        }
    }
}

Cut your code sample down to the few small blocks you want ideas for, this much code makes it read like you just want us to do your full refactor for you. — Jimmy Hoffa
– Jimmy Hoffa, Commented Aug 27, 2010 at 14:38
@Jimmy Hoffa: sorry about the long code snippet - I thought that showing you the whole context would be helpful in seeing what my problem was - the nested linq statements ... but believe me, this is massively stripped down from what the project code is really. — Greg
– Greg, Commented Aug 27, 2010 at 15:06

Ocelot20 · Accepted Answer · 2010-08-27 15:07:18Z

1

Using some made-up constructors to oversimplify:

public static Element Load(int id)
{
    using (var db = DataContextFactory.Create<ElementContext>())
    {
        var translations = from t in db.Translations
                           where t.Fk_Element_Id == id
                           join l in db.Languages on t.FK_Language_Id equals l.Id
                           select new Translation(t, l);

        return new Element(db.Elements.Where(x => x.Id == id).Single(), translations);
    }
}

answered Aug 27, 2010 at 15:07

Ocelot20

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1 Comment

Greg Over a year ago

That's the kind of thing I was hoping for - I'm not too sure how lambda expressions work, but with your example I hope I'll learn faster. Thanks!

Jimmy Hoffa · Accepted Answer · 2010-08-27 14:46:45Z

0

First thing I don't like in here is all the "new Translation() { bla = bla } because they're big blocks of code, I would put them in a method where you hand them the objects and they return the new for you.

Translations.InsertOnSubmit(CreateDatabaseTranslation(dbElement, translation));

and

trans.Add(CreateTranslationWithLanguage(translation, dbLanguage));

etc, wherever you have code like this, it just muddles the readability of what you're doing in here.

edited Aug 27, 2010 at 14:46

answered Aug 27, 2010 at 14:41

Jimmy Hoffa

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