Alex (Xtensive) wrote:

It seems there is a bug in Domain model builder allowing you to use [Association(PairTo = ...)] on both sides of relationship - that's wrong, this attribute must be used only on one side. The side it is applied to becomes "virtual": no data structures are created for it, it relies on structures created for another side instead.

Try to fix this issue first. I'll create a bug report about this.

Btw, I think you must switch from using "Doctors" and "Specialities" to "Doctor" and "Speciality". Plural class names are quite untypical in .NET world.

Alex (Xtensive) wrote:

Ok, I just implemented everything in test. Conclusions:

1) Bug in code you've provided: for (var r in list) ... doesn't compile - by obvious reason.

2) Absence of [HierarchyRoot] at your types was leading to this exception:

System.ArgumentException : Type 'Speciality' is not registered.
at Xtensive.Storage.Model.TypeInfoCollection.get_Item(Type key) in TypeInfoCollection.cs: line 65
at Xtensive.Storage.Key.Create(Domain domain, Type type) in Key.cs: line 341
at Xtensive.Storage.Entity..ctor() in Entity.cs: line 623
at Xtensive.Storage.Tests.Issues.Issue679And681.Speciality..ctor()
at Xtensive.Storage.Tests.Issues.Issue679And681Test.BuildTest() in Issue679,681_EntitySetRelatedBugs.cs: line 67

3) Bug with [PairTo] was actually a "feature" - i.e. everything was ok if you declare pairing on both sides. I added the following check: if multiplicity is one-to-one or many-to-many, an exception will be thrown, since in this case it's impossible to determine which side of relationship must be "virtual". Before this new check this was dependent on type registration order, which is wrong (reg. order change would lead to schema change).

So now you can use such declarations only with many-to-one relationship. But I should mention everything worked fine even without this fix.

Test code is here: http://goo.gl/qaWW

Its output:

Speciality1 Doctor1 email1@host.com
Speciality1 Doctor2 email2@host.com

Alex (Xtensive) wrote:

Just checked your case:

1032/7     INFO Core.Diagnostics         Core.Diagnostics log initialized.
 1095/7     INFO Core.Diagnostics         Storage.Building log initialized.
 1218/7     INFO Core.Diagnostics             Storage log initialized.
 1819/7     INFO Core.Diagnostics             Storage.Providers.Sql log initialized.
 2724/7     INFO Core.Diagnostics             Modelling log initialized.
 4208/7     INFO Core.Diagnostics         Storage.Tests log initialized.
 4209/7    ERROR Storage.Tests            Xtensive.Storage.Tests.Issues.Issue679And681Test
 4210/7    ERROR Storage.Tests            Exception!
Original error:
Xtensive.Storage.DomainBuilderException: Paired field 'Speciality' was not found in 'Doctor' type.
   at Xtensive.Storage.Building.Builders.AssociationBuilder.BuildPairedAssociation(AssociationInfo slave, String masterFieldName) in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Building\Builders\AssociationBuilder.cs:line 49
   at Xtensive.Storage.Building.Builders.ModelBuilder.BuildAssociations() in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Building\Builders\ModelBuilder.cs:line 152
   at Xtensive.Storage.Building.Builders.ModelBuilder.BuildModel() in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Building\Builders\ModelBuilder.cs:line 102
   at Xtensive.Storage.Building.Builders.ModelBuilder.Run() in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Building\Builders\ModelBuilder.cs:line 58
   at Xtensive.Storage.Building.Builders.DomainBuilder.BuildModel() in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Building\Builders\DomainBuilder.cs:line 213
   at Xtensive.Storage.Building.Builders.DomainBuilder.BuildDomain(DomainConfiguration configuration, DomainBuilderConfiguration builderConfiguration) in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Building\Builders\DomainBuilder.cs:line 60
   at Xtensive.Storage.Upgrade.UpgradingDomainBuilder.BuildStageDomain(UpgradeStage stage) in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Upgrade\UpgradingDomainBuilder.cs:line 74
   at Xtensive.Storage.Upgrade.UpgradingDomainBuilder.Build(DomainConfiguration configuration) in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Upgrade\UpgradingDomainBuilder.cs:line 54
   at Xtensive.Storage.Domain.Build(DomainConfiguration configuration) in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage\Domain.cs:line 225
   at Xtensive.Storage.Tests.AutoBuildTest.BuildDomain(DomainConfiguration configuration) in E:\My Projects\Hg\DataObjects.Net\Xtensive.Storage\Xtensive.Storage.Tests.Core\AutoBuildTest.cs:line 71

Xtensive.Storage.DomainBuilderException : Paired field 'Speciality' was not found in 'Doctor' type.
at Xtensive.Storage.Building.Builders.AssociationBuilder.BuildPairedAssociation(AssociationInfo slave, String masterFieldName) in AssociationBuilder.cs: line 49
at Xtensive.Storage.Building.Builders.ModelBuilder.BuildAssociations() in ModelBuilder.cs: line 152
at Xtensive.Storage.Building.Builders.ModelBuilder.BuildModel() in ModelBuilder.cs: line 102
at Xtensive.Storage.Building.Builders.ModelBuilder.Run() in ModelBuilder.cs: line 58
at Xtensive.Storage.Building.Builders.DomainBuilder.BuildModel() in DomainBuilder.cs: line 213
at Xtensive.Storage.Building.Builders.DomainBuilder.BuildDomain(DomainConfiguration configuration, DomainBuilderConfiguration builderConfiguration) in DomainBuilder.cs: line 60
at Xtensive.Storage.Upgrade.UpgradingDomainBuilder.BuildStageDomain(UpgradeStage stage) in UpgradingDomainBuilder.cs: line 74
at Xtensive.Storage.Upgrade.UpgradingDomainBuilder.Build(DomainConfiguration configuration) in UpgradingDomainBuilder.cs: line 54
at Xtensive.Storage.Domain.Build(DomainConfiguration configuration) in Domain.cs: line 225
at Xtensive.Storage.Tests.AutoBuildTest.BuildDomain(DomainConfiguration configuration) in AutoBuildTest.cs: line 76
at Xtensive.Storage.Tests.AutoBuildTest.TestFixtureSetUp() in AutoBuildTest.cs: line 31

So likely, there was something different.

Alex (Xtensive) wrote:

Can you send us your sample?

Yes, you can write "select spec.Title + m.FullName + m.Email" there, but in this case this will be executed as SQL, so you will get just this string as result, none of objects will be materialized (i.e. if you'll use them later in the same transaction, they'll need to be fetched).

Dmitri Maximov (Xtensive) wrote:

Hello Diego,

it seems that you have a mistake in the model, I mean, values of PairTo property of Association attribute were wrong. Here is the correct snippet:

[Field]
[Association(PairTo = "Specialities")]
public EntitySet<Doctor> Doctors { get; private set; }

&

[Field]
[Association(PairTo = "Doctors")]
public EntitySet<Speciality> Specialities { get; private set; }

psulek wrote:

First, I have a Windows Service where I use DataObjects. I have a socket server implementation inside them, and I have some operations that I call with a socket client that I have programmed in the socket server. All the operations until now work well, except an operation that relates Speciality and Doctor entities. As you know early we made a LINQ query that list all the doctors that belong to an specific Speciality. The following code makes that: var spec = Query.Single<speciality>(1); var list = from m in spec.Doctors select new { [b]spec.Title, m.FullName, m.Email[/b] }; Trying to obtain the output result, I have the following piece of code: string outResult; foreach (var item in list) //There is an exception { outResult = item.Title + ", " + item.FullName + ", " + item.Email + ";"; } Assuming the definition of the Doctor Entity and Speciality, I have the following: [HierarchyRoot] public class Speciality : Entity { [Field, Key] public int Id { get; private set; } [Field(Length = 50)] public string Title { get; set; } [Field] public bool Activ { get; set; } [Field] [Association(PairTo = "Speciality")] public EntitySet<doctor> Doctors { get; private set; } } } public class Doctor: Entity { [Field, Key] public int Id { get; private set; } [Field(Length = 50)] public string FulllName{ get; set; } [Field] public string Email { get; set; } [Field] [Association(PairTo = "Doctor")] public EntitySet<speciality> Specialities { get; private set; } } I have observed that the exception: {"Invalid TupleDescriptor. Expected descriptor is TupleDescriptor(Int32, Int32, String, Boolean).\r\nParameter name: difference"} relates to the Doctor entity definition, because assuming the data types parameters is the same to the Doctor entity columns, except by the second parameter that belongs the TypeId property that correspond to the DataObjects.net implementation. Really I dont know why I received this exception. Alex if you need more clarification,just tell me.I hope it is understood. Sorry for my poor english. Thanks in advance.

I found 2 errors in your sample: 1. on both classes you missing attribute [HierarchyRoot] 2. you have wrong construction of anonymous type in final select projection, you have:

select new {spec.Title, m.FulllName, m.Email};

But definition must be like that:

select new {Title = spec.Title, FullName = m.FulllName, Email = m.Email};

Important here is that you must specify names of properties for anonymous type like Title, FullName, Email

Here is working code that i update:

var config = DomainConfiguration.Load("Default");
var domain = Domain.Build(config);

using (Session.Open(domain))
{
    using (var transactionScope = Transaction.Open())
    {
        // Creating new persistent object
        var speciality = new Specialities
        {
            Activ = true,
            Title = "Specialist 1",
        };

        speciality.Doctors.Add(new Doctors
                                   {
                                       FulllName = "House MD.",
                                       Email = "house@md.com"
                                   });

        // Committing transaction
        transactionScope.Complete();
    }
}

using (Session.Open(domain))
{
    using (var transactionScope = Transaction.Open())
    {
        var spec = Query.Single<Specialities>(1);
        var list = from m in spec.Doctors
                   select new {Title = spec.Title, FullName = m.FulllName, Email = m.Email};

        string outResult;
        foreach (var item in list) //There is an exception
        {
            outResult = item.Title + ", " + item.FullName + ", " + item.Email + ";";
        }
    }
}

psulek wrote:

And which version of DO4 do you have? I have tested it on 4.3RC2 with success. I dont know how to help you more, can you post sample (zip with solution and project) which does not work for you. Or some details how are named your existing DB, and sample data information you have in existing tables, that i can reconstruct your case properly.

Alex (Xtensive) wrote:

Does this correct: the question isn't about how to perform the LINQ query (that's described in Manual), but how to serialize client-side query, send it to server and get back the results?

If I'm wrong, please describe what you're going to perform more precisely. Unfortunately, I really don't have enough time to figure out this from posted solutions...

psulek wrote:

if you want to pass DO linq query from client to server, you must serialized linq query expression on client side like this:

var query = Query.All<Person>().Where(person => person.Name = "xyz");
var serializedExpression = query.Expression.ToSerializableExpression();
byte[] buffer;
using (MemoryStream serializationStream = new MemoryStream())
{
  new BinaryFormatter().Serialize(serializationStream, serializedExpression);
  buffer = serializationStream.GetBuffer();
}

here buffer will contains byte array of serialized expression which will be passed to server (by any channel-wcf/socket/...)

and deserialize byte array to expression on server side:

byte[] inputData = ...

using(MemoryStream serializationStream = new MemoryStream(buffer))
{
   serializationStream.Position = 0;
   var serializedExpression = (SerializableExpression)new BinaryFormatter().Deserialize(serializationStream);
   var deserializedExpression = serializedExpression.ToExpression();
   var query = new Xtensive.Storage.Linq.Queryable<Person>(expression);
}

// iterate 'query' by foreach, etc...

Here you can also on client side serialize assembly qualified type name of type T you are quering agains Query.All<t> and put this information into buffer. On server side you can deserialize this assembly qualified type name and build runtime Type (Type.GetType(string)). Server side example:

Type entityType = deserializeEntityType();
Type makeGenericType = typeof(Queryable<>).MakeGenericType(entityType);
IQueryable<Entity> queryable = Activator.CreateInstance(makeGenericType, deserializedExpression);

Alex (Xtensive) wrote:

We can download & task the code, but normally we do this for paid customers only. Another reason is language: most of us know English and Russian, but not Spanish. Imagine we'd ask to to study the code with Russian type and field names.

So I'd recommend you to try narrow down the case. Questions like "The problem is HOW CAN I WRITE THE LINQ QUERY" look simply strange, taking into account there is a large part in manual about this. I.e. ask more precise question.

E.g. I simply don't understand what is implied here, although I read everything. If someone else understands the case, I'd be happy to hear the explanation...

I'm sorry for such an answer, but this is the case when it's difficult to help, because there is no precise question.