LINQ to Entity: How to cast a complex type to a DTO

Question

Background:

1. I have created a function import which is available in my context object as GetJournalViewItemsQuery()

2. The function import returns a complex type called JournalViewItem.

3. Now when I try to load the JournalViewItem into my application DTO called JournalEntry I come up with error:

   Error 7 Cannot implicitly convert type 'MyApp.Infrastructure.Models.JournalEntry' to 'MyApp.SqlData.JournalViewItem'

This is the code:

             var journalEntry =  Context.GetJournalViewItemsQuery()
                .Where(i => i.JournalItemId == _journalEntryId)
                .Select(x => new JournalEntry(x.JournalItemId,
                    x.HeaderText,x.JournalText, x.LastUpdatedOn,
                    x.JournalItemTypeId)).Single();

The error happens at the "new JournalEntry" line.

My question: How can I cast the JournalViewItem complex type to my DTO ?

Thank you

After @JanR suggestion I still have the same problem. The modified code is:

       var journalEntry = Context.GetJournalViewItemsQuery()
             .Where(i => i.JournalItemId == _journalEntryId)
             .Select(x => new JournalEntry
             {
                 JournalEntryNumber = x.JournalItemId,
                 HeaderText = x.HeaderText,
                 BodyText = x.JournalText,
                 LastUpdatedOn = x.LastUpdatedOn,
                 JournalEntryType = x.JournalItemTypeId
             }).Single();

I found out the reason for my problem. I failed to mention (my apologies) that I'm working off generated code from WCF RIA Domain Services for Silverlight application. As such the Context.GetJournalViewItemsQuery() needs to be executed and THEN I can query the results on my callback method using the LINQ expression that @Chuck.Net and JanR have suggested.

Here's the working code to those who might be interested:

        public IList<JournalEntryHeader> GetJournalEntryHeaders()
    {
        PerformQuery<JournalViewItem>(Context.GetJournalViewItemsQuery(), GetJournalEntryHeadersFromDbComplete);

        return _journalHeaders;
    }

    void PerformJournalEntryHeadersQuery(EntityQuery<JournalViewItem> qry,
                            EventHandler<EntityResultsArgs<JournalViewItem>> evt)
    {
        Context.Load<JournalViewItem>(qry, r =>
        {
            if (evt != null)
            {
                try
                {
                    if (r.HasError)
                    {
                        evt(this, new EntityResultsArgs<JournalViewItem>(r.Error));
                    }
                    else if (r.Entities.Count() > 0)
                    {
                        evt(this, new EntityResultsArgs<JournalViewItem>(Context.JournalViewItems));
                    }
                    else if (r.Entities.Count() == 0 && _currentJournalItemsPage > 0)
                    {
                        GetPrevPageJournalEntryHeadersAsync();
                    }
                }
                catch (Exception ex)
                {
                    evt(this, new EntityResultsArgs<JournalViewItem>(ex));
                }
            }
        }, null);
    }


    void GetJournalEntryHeadersFromDbComplete(object sender, EntityResultsArgs<JournalViewItem> e)
    {
        if (e.Error != null)
        {
            string errMsg = e.Error.Message;
        }
        else
        {
            _journalHeaders = e.Results
                .Select(
            x => new JournalEntryHeader(x.JournalItemId,
                                     x.ProjectName,
                                     x.TopicName,
                                     x.HeaderText,
                                     x.EntryTypeName,
                                     x.LastUpdatedOn)).ToList();

            GetJournalEntryHeadersComplete(this, new JournalEntryHeaderItemsEventArgs(_journalHeaders));
        }
    }

Answer 1

I found out the reason for my problem. I failed to mention (my apologies) that I'm working off generated code from WCF RIA Domain Services for Silverlight application. As such the Context.GetJournalViewItemsQuery() needs to be executed and THEN I can query the results on my callback method using the LINQ expression that @Chuck.Net and JanR have suggested.

You'll find the answer in the original post where I entered the question.