/Prototypes/AomDB/NAomDAL/DAL/EntityRepository.cs

#region Copyright

// 

// Copyright (C) 2008 VirtualStaticVoid <virtualstaticvoid@gmail.com>

// 

// This program is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

// 

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// 

// You should have received a copy of the GNU General Public License

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//

#endregion



using System;

using System.Data.Linq;

using System.Data.Linq.Mapping;

using System.Linq;

using System.Linq.Expressions;

using System.Xml.Linq;

using NAom.Core;



namespace NAom.DAL

{

  public class EntityRepository<TEntity> : IRepository<TEntity>

    where TEntity : class, IEntity  //, new()

  {



    private readonly DynamicType<TEntity> _dynamicType;

    private readonly IDynamicTypeFactory<TEntity> _dynamicTypeFactory;



    private readonly DataContext _dbCtx;

    private readonly ITable _linq2SQLTable;



    public EntityRepository(EntityType entityType)

    {

      EntityType = entityType;



      _dynamicType = CreateDynamicType(entityType);

      _dynamicTypeFactory = _dynamicType.CreateFactory();



      #region Goo



      // since Type.GetType(string) != _dynamicTypeFactory.GeneratedType for dynamic assemblies,

      //  DataContext.GetTable() fails with InvalidOperationException: Could not retrieve a Table for inheritance subtype 'TDynamicType', try Table of TDynamicType instead. 

      // hook up TypeResolve, so that the correct type can be returned to

      //  the DataContext when it's busy reflecting

      Type generatedType = _dynamicTypeFactory.GeneratedType;



      ResolveEventHandler resolveEventHandler = (o, e) =>

      {

        if (String.CompareOrdinal(generatedType.FullName, e.Name) == 0)

          return generatedType.Assembly;

        return null;

      };



      AppDomain.CurrentDomain.TypeResolve += resolveEventHandler;



      #endregion



      _dbCtx = CreateDataContext(entityType, _dynamicTypeFactory.GeneratedType);

      _linq2SQLTable = GetTable(_dynamicTypeFactory.GeneratedType);



      #region Goo



      // clean up, remove handler

      AppDomain.CurrentDomain.TypeResolve -= resolveEventHandler;



      #endregion



#if DEBUG

      _dbCtx.Log = Console.Out;

#endif



    }



    public EntityType EntityType { get; private set; }



    #region IRepository<TEntity> Members



    public TEntity CreateInstance()

    {

      return _dynamicTypeFactory.CreateInstance();

    }



    public IQueryable<TEntity> GetAll()

    {

      return new InternalEntityQueryable<TEntity>

        (

          _dynamicTypeFactory.GeneratedType,

          _linq2SQLTable.AsQueryable().OfType<TEntity>()

        );

    }



    public IQueryable<TEntity> Find(Expression<Func<TEntity, bool>> expression)

    {

      return GetAll().Where(expression);

    }



    public void Add(TEntity entity)

    {

      _linq2SQLTable.InsertOnSubmit(entity);

      _dbCtx.SubmitChanges();

    }



    public void Update(TEntity entity)

    {

      _linq2SQLTable.DeleteOnSubmit(entity);

      _dbCtx.SubmitChanges();

    }



    public void Delete(TEntity entity)

    {

      _linq2SQLTable.DeleteOnSubmit(entity);

      _dbCtx.SubmitChanges();

    }



    public void Delete(Expression<Func<TEntity, bool>> expression)

    {

      foreach (TEntity entity in GetAll().Where(expression))

      {

        _linq2SQLTable.DeleteOnSubmit(entity);

      }

      _dbCtx.SubmitChanges();

    }



    #endregion



    #region Support



    private static DynamicType<TEntity> CreateDynamicType(EntityType entityType)

    {

      Type genericPropertyTypeType = typeof(PropertyType<>);



      DynamicType<TEntity> dynamicType = new DynamicType<TEntity>(entityType.Name);



      // add required property types

      dynamicType.Properties.AddRange(InterfaceSupport.DerivePropertyTypes(typeof(IEntity)));



      // now add user-defined properties

      foreach (IInternalAttributeType attributeType in entityType.AttributeTypes)

      {

        Type propertyTypeType = genericPropertyTypeType.MakeGenericType(attributeType.RealDataType);

        IPropertyType propertyType = (IPropertyType)Activator.CreateInstance(propertyTypeType, new object[] { attributeType.Name });

        dynamicType.Properties.Add(propertyType);



        // store for later

        attributeType.PropertyType = propertyType;

      }



      return dynamicType;



    }



    private static DataContext CreateDataContext(EntityType entityType, Type generatedType)

    {



      // generate Linq2SQL mapping

      XDocument mappingXmlDoc = CreateXmlMappingSource(entityType, generatedType);



      // load it

      XmlMappingSource mappingSource = XmlMappingSource.FromXml(mappingXmlDoc.ToString());



      // create the data context using this mapping

      DataContext dbCtx = new DataContext(Properties.Settings.Default.AomDBConnectionString, mappingSource);



      return dbCtx;

    }



    private ITable GetTable(Type generatedType)

    {

      // get the table for the generated type

      return _dbCtx.GetTable(generatedType);

    }



    private static XDocument CreateXmlMappingSource(EntityType entityType, Type generatedType)

    {

      // NOTE: 

      //  The Name column is set as the primary key, since scope_identity() doesn't work

      //  for views which have "instead of" triggers



      XElement typeXElement;

      XNamespace xmlns = "http://schemas.microsoft.com/linqtosql/mapping/2007";

      XDocument mappingXmlDoc = new XDocument

        (

        new XElement

          (

            xmlns + "Database",

            new XAttribute("xmlns", xmlns.NamespaceName),

            new XAttribute("Name", "AomDB"),

            new XElement

            (

              xmlns + "Table",

              new XAttribute("Name", entityType.GeneratedViewName),

              typeXElement = new XElement

               (

                 xmlns + "Type",

                 new XAttribute("Name", generatedType.FullName),

                 new XElement

                 (

                    xmlns + "Column",

                    new XAttribute("Name", "Id"),

                    new XAttribute("Member", "Id"),

                    new XAttribute("Storage", "_dynamicId"),

                    new XAttribute("AutoSync", "OnInsert"),

                    new XAttribute("IsDbGenerated", true),

                    new XAttribute("CanBeNull", false),

                    new XAttribute("UpdateCheck", "Never")

                 ),

                 new XElement(xmlns + "Column", new XAttribute("Name", "Version"), new XAttribute("Member", "Version"), new XAttribute("Storage", "_dynamicVersion"), new XAttribute("AutoSync", "Always"), new XAttribute("IsDbGenerated", true), new XAttribute("IsVersion", true), new XAttribute("CanBeNull", false), new XAttribute("UpdateCheck", "Never")),

                 new XElement(xmlns + "Column", new XAttribute("Name", "Name"), new XAttribute("Member", "Name"), new XAttribute("Storage", "_dynamicName"), new XAttribute("IsPrimaryKey", true), new XAttribute("CanBeNull", false), new XAttribute("UpdateCheck", "Never"))

               )

            )

          )

        );



      foreach (IInternalAttributeType attributeType in entityType.AttributeTypes)

      {

        typeXElement.Add

          (

            new XElement

              (

                xmlns + "Column",

                new XAttribute("Name", attributeType.Name),

                new XAttribute("Member", attributeType.Name),

                new XAttribute("Storage", "_dynamic" + attributeType.Name),

                new XAttribute("CanBeNull", !attributeType.RealDataType.IsValueType),

                new XAttribute("UpdateCheck", "Never")

              )

          );

      }



      return mappingXmlDoc;

    }



    #endregion



  }

}