Any reason why this statement is working in Linq and not in Linq To LLBLGen

Dim md As New LinqMetaData()
Dim P As PersonEntity = md.Perons.Single(Function(o) o.First = "Mario" And o.Last = "Rossi")

Insteda this one work in both:

Dim md As New LinqMetaData()
Dim P As PersonEntity = md.Perons.Single(Function(o) o.First = "Mario")

Can I use the And statement in a .Single construct like in Linq to SQL?

Thanks.

Please provide more information: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=12769

Version 2.6 Final 12 September 2008

Using Linq to SQL no prob.

Using LLBL i get: An object or column name is missing or empty. For SELECT INTO statements, verify each column has a name. For other statements, look for empty alias names. Aliases defined as "" or [] are not allowed. Add a name or single space as the alias name.

That seems like if with the And construct in .Single the LLBL has built a "wrong" SELECT.

md.Perons.Single(Function(o) o.First = "Mario" And o.Last = "Rossi")

the problem is very easy to reproduce.

Anyway I have also attached the stack

A weird message in this context :

http://codebetter.com/blogs/david.hayden/archive/2008/10/31/linq-to-sql-is-dead-read-between-the-lines.aspx

This was fixed on October 17th. The fix isn't out yet, but you can get the latest build with that fix from this message: http://www.llblgen.com/TinyForum/GotoMessage.aspx?MessageID=81455&ThreadID=14606

Thanks, I will try an let You Know.

No, The problem is the same...

The best I was able to do is to build a small solution You will find: 1) the dal project LLBLGen Fiel 2) A solution with two projs: the Dal and the test App. 3) A small MDF file to attach to Your SQL 4) 3 lines of code

I have moved the dll to a different file.zip named bin to take less space on the attachments. (to be copied on both Dal and App bin folders)

You will need to change the PW to your server pw on the config file..

Please let me knwon, Thanks.

Just to confirm that wih Linq to SQL is working...

      Dim Md As New LinqMetaData()
      Dim Db As New DataClasses1DataContext

      ' Working LLBLGen
      ' Dim A As PersonEntity = md.Person.Single(Function(o) o.Name = "Mario Rossi")

      ' Working with Linq to SQL
      ' Dim A As Person = Db.Person.Single(Function(o) o.Name = "Mario Rossi" And o.DateOfBirth > #1/1/1950#)

      ' Not working in LLBLGen! (With And...)
      Dim A As PersonEntity = Md.Person.Single(Function(o) o.Name = "Mario Rossi" And o.DateOfBirth > #1/1/1950#)

      With Me.DataGridView1
          .DataSource = A.Dog
      End With

Will look into it.

The 'And' is converted by the vb.net compiler in a bitwise Expression type 'And', you should use AndAlso instead of 'And' in these kind of predicates.

Not working, even with AndAlso, You can try on the solution I posted changing the code to:

Dim A As PersonEntity = Md.Person.Single(Function(o) o.Name = "Mario Rossi" AndAlso o.DateOfBirth > #1/1/1950#)

... for me same result.

Antonio wrote:

Not working, even with AndAlso, You can try on the solution I posted changing the code to:

Dim A As PersonEntity = Md.Person.Single(Function(o) o.Name = "Mario Rossi" AndAlso o.DateOfBirth > #1/1/1950#)

... for me same result.

Hmm... works in C#, will see what the VB.NET specifics are of this... (as the VB.NET compiler sometimes creates different expression trees)

I confirm in c# is Working:

LinqMetaData Md = new LinqMetaData();
DateTime D = new DateTime(1950, 1, 1, 0, 0, 0);
PersonEntity A = Md.Person.Single(o => o.Name == "Mario Rossi" && o.DateOfBirth.Value > D);
dataGridView1.DataSource = A.Dog;

... as You have said only with && .... but in VB with AndAlso is not working anyway.

... bha!!!

Antonio wrote:

I confirm in c# is Working:

LinqMetaData Md = new LinqMetaData();
DateTime D = new DateTime(1950, 1, 1, 0, 0, 0);
PersonEntity A = Md.Person.Single(o => o.Name == "Mario Rossi" && o.DateOfBirth.Value > D);
dataGridView1.DataSource = A.Dog;

... as You have said only with && .... but in VB with AndAlso is not working anyway.

... bha!!!

With VB.NET:

<Test()> _
    Public Sub SimpleSingleCallWithMultiplePredicatesUsingAnd()
        Using adapter As New DataAccessAdapter()
            Dim metaData As New LinqMetaData(adapter)
            Dim q = metaData.Customer.Single(Function(c) c.CustomerId = "CHOPS" AndAlso c.Country = "Switserland")
            Assert.IsNotNull(q)
        End Using
    End Sub

Works OK.

With 'And' it doesn't. (It is hard to determine what the user wants in that case with the expression tree at hand, so please use AndAlso)

Be aware that 'Single' will throw an exception if 0 or 2 or more rows are returned, your query has to return exactly 1 row. That's how 'Single' is defined by Microsoft. It's IMHO not really a practical method. You can also use First() with the same filter, which doesn't throw an exception. So I'm interested in what exception you're getting with the build I pointed you to. (looking at your predicates, I can imagine more than 1 row or 0 rows are returned)

Dear Frans,

No. As You can see from my previous posts... I have tried the same code in two ways...

Staight Linq to SQL and works... LLBL Gen Linq with && in C# and works...

With VB release 6Oct, DLL Linq support updated, Self Servicing and 'AndAlso'.... And non work!

'Mario Rossi' anyway returns only one row, as obvius from the above two statements... (Work in Linq To SQL and LLBLGEN C#)

I'm not so expert to give You the right debug infos... on LINQ... That's why i have done a little demo project and I have posted to You.

To debug You can just attach the little test database... copy the bin files... and run the project! .... and You will be, better than me able to trace the error.

Thanks. Antonio.

Sorry for the delay, we always try to add a reprocase to our own tests so we keep it around.

I see that your case is different than the one I tested: you have a Nullable(Of T) type in the predicate. If you use: Dim A As PersonEntity = md.Person.Single(Function(o) o.Name = "Mario Rossi" AndAlso o.DateOfBirth.Value > #1/1/1950#)

instead of Dim A As PersonEntity = md.Person.Single(Function(o) o.Name = "Mario Rossi" AndAlso o.DateOfBirth > #1/1/1950#)

It works. The reason is explained here (Second Note box under 'Aggregates').

This is indeed unfortunate, however we were unable to provide proper code which always works for this particular situation.

This might sound like a lame excuse but the problem is that there is no documentation about what a compiler produces exactly, given a linq query, so it's for us, outside Microsoft, not clear what to expect in all situations, hence the workaround for this situation instead of a routine which does work properly for this particular situation.

My respect to all people who taking care of the work like You Thanks for all.