How to: Merge FluentMetadataSources

This article is relevant to entity models that utilize the deprecated Visual Studio integration of Telerik Data Access. The current documentation of the Data Access framework is available here.

The AggregateMetadataSource can be used to combine other MetadataSource instances and produce a new MetadataContainer that contains the combined metadata. The purpose of this tutorial is to show you how to work with AggregateMetadataSource.

It is not possible to use the AggregateMetadataSource class for merging data from different database.

For this walkthrough, the following projects and classes will be used. In order to use the AggregateMetadataSource, you will need to add references to Telerik.OpenAccess.dll and Telerik.OpenAccess.35.Extensions.dll in your projects.

Project AssemblyA - it contains the following classes:

• Person - the Person object has a reference to Address, which is defined in the AssemblyB.

  using AssemblyB;
  namespace AssemblyA
  {
      public class Person
      {
          public string Name { get; set; }
          public int Id { get; set; }
          public Address Address { get; set; }
      }
  }
  

  Imports AssemblyB
  Public Class Person
      Public Property Name() As String
      Public Property Id() As Integer
      Public Property Address() As Address
  End Class
  

• FluentMetadataSourceA - a custom FluentMedataSource class that provides a mapping configuration for the Person class.

  using System.Collections.Generic;
  using Telerik.OpenAccess.Metadata.Fluent;
  namespace AssemblyA
  {
     public class FluentMetadataSourceA : FluentMetadataSource
     {
         protected override IList<MappingConfiguration> PrepareMapping()
         {
             IList<MappingConfiguration> preparedConfigurations = new List<MappingConfiguration>();
             MappingConfiguration<Person> personConfiguration = new MappingConfiguration<Person>();
             personConfiguration.MapType().ToTable("People");
             preparedConfigurations.Add(personConfiguration);
             return preparedConfigurations;
         }
     }
  }
  

  Imports Telerik.OpenAccess.Metadata.Fluent
  Public Class FluentMetadataSourceA
      Inherits FluentMetadataSource
      Protected Overrides Function PrepareMapping() As IList(Of MappingConfiguration)
          Dim preparedConfigurations As IList(Of MappingConfiguration) = New List(Of MappingConfiguration)()
          Dim personConfiguration As New MappingConfiguration(Of Person)()
          personConfiguration.MapType().ToTable("People")
          preparedConfigurations.Add(personConfiguration)
          Return preparedConfigurations
      End Function
  End Class
  

Project AssemblyB - it contains the following classes:

• Address

  namespace AssemblyB
  {
     public class Address
     {
         public string Country { get; set; }
         public string Street { get; set; }
     }
  }
  

  Public Class Address
      Public Property Country() As String
      Public Property Street() As String
  End Class
  

• FluentMetadataSourceB - a custom FluentMedataSource class that provides a mapping configuration for the Address class.

  using System.Collections.Generic;
  using Telerik.OpenAccess.Metadata.Fluent;
  namespace AssemblyB
  {
     public class FluentMetadataSourceB : FluentMetadataSource
     {
         protected override IList<MappingConfiguration> PrepareMapping()
         {
             IList<MappingConfiguration> preparedConfigurations = new List<MappingConfiguration>();
             MappingConfiguration<Address> addressConfiguration = new MappingConfiguration<Address>();
             addressConfiguration.MapType().ToTable("Addresses");
             preparedConfigurations.Add(addressConfiguration);
             return preparedConfigurations;
         }
     }
  }
  

  Imports Telerik.OpenAccess.Metadata.Fluent
  Public Class FluentMetadataSourceB
      Inherits FluentMetadataSource
      Protected Overrides Function PrepareMapping() As IList(Of MappingConfiguration)
          Dim preparedConfigurations As IList(Of MappingConfiguration) = _
              New List(Of MappingConfiguration)()
          Dim addressConfiguration As New MappingConfiguration(Of Address)()
          addressConfiguration.MapType().ToTable("Addresses")
          preparedConfigurations.Add(addressConfiguration)
          Return preparedConfigurations
      End Function
  End Class
  

The AggregateMetadataSource can be used in the following manner:

AggregateMetadataSource aggregateMetadataSource = new AggregateMetadataSource(
    new FluentMetadataSourceA(), new FluentMetadataSourceB(), AggregationOptions.Late);
MetadataContainer metadataContainer = aggregateMetadataSource.GetModel();

Dim _aggregateMetadataSource As New AggregateMetadataSource(New FluentMetadataSourceA(), _
    New FluentMetadataSourceB(), AggregationOptions.Late)
Dim _metadataContainer As MetadataContainer = _aggregateMetadataSource.GetModel()

The merged metadata container will contain two persistent types - Address and Person.

The AggregateMetadataSource class uses a special algorithm internally to resolve references when merging objects. Suppose you have a class A and a class B, which classes you want to merge. Class A has a reference to class C. In this case, when you merge class A and class B, the AggregateMetadataSource class cannot resolve the reference from A to C out of the box. Reference resolution can be controlled by specifying AggregationOptions in the AggregateMetadataSource. For more information, check out the How to: Control Reference Resolution topic.

You can consume the merged metadata container as described in Passing the Metadata to the OpenAccessContext.