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Wednesday, February 22, 2006

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DataManager Class with IsolatedContext for WilsonORMapper

In case someone else would like to know how to create a singleton DataManager class for WilsonORMapper that uses IsolatedContext and works in ASP.NET...

View DataManager.cs

using System.Configuration;
using System.IO;
using System.Reflection;
using System.Web;
using Wilson.ORMapper;

namespace Portal.Data
{
   /// <summary>
   /// The DataManager class is the singleton instance of the ObjectSpace class
   /// </summary>
   public sealed class DataManager
   {
       private const string MAPPING_FILE = "Mapping.config";
        private static readonly Guid CONTEXT_KEY = Guid.NewGuid();

       /// <summary>The application connection string read from app.config</summary>
       /// <example>
       /// Add the following key to the "appSettings" section of your config:
       /// <code><![CDATA[
       ///    <configuration>
       ///           <appSettings>
       ///               <add key="IMI.Portal.Framework.Data.ConnectionString" value="Data Source=(local);Initial Catalog=DATABASE;User ID=USERNAME;Password=PASSWORD;" />
       ///           </appSettings>
       ///    </configuration>
       /// ]]></code>
       /// </example>
       public static readonly string ConnectionString = ConfigurationSettings.AppSettings["ConnectionString"];
       public static readonly string CurrentProvider = ConfigurationSettings.AppSettings["Provider"];

       /// <summary>The singletion instance of an ObjectSpace Class</summary>
       private static ObjectSpace objectSpace; // = GetDefaultInstance();
       private static object syncLock = new object();

       private DataManager()
       { }

       #region public static ObjectSpace ObjectSpace

       /// <summary>The singleton method for retrieving the global ObjectSpace</summary>
       public static ObjectSpace ObjectSpace
       {
           get
           {
               if (objectSpace == null)
               {
                   lock (syncLock)
                   {
                       if (objectSpace == null)
                       {
                           objectSpace = GetDefaultInstance();
                       }
                   }
               }

               HttpContext context = HttpContext.Current;
               if (context != null)
               {
                   ObjectSpace isolatedContext = (ObjectSpace) context.Items[CONTEXT_KEY];
                   if (isolatedContext == null)
                   {
                       // Cache the isolated context in the current request so that it is used
                       // throughout the entire request

                       isolatedContext = objectSpace.IsolatedContext;
                       context.Items[CONTEXT_KEY] = isolatedContext;
                   }
                   return isolatedContext;
               }
               else
               {
                   return objectSpace;
               }
           }
       }

       #endregion

       #region private static ObjectSpace GetDefaultInstance()

       private static ObjectSpace GetDefaultInstance()
       {
           Assembly assembly = Assembly.GetAssembly(typeof(DataManager));

           using (Stream mappingStream = assembly.GetManifestResourceStream(
               typeof(DataManager),
               MAPPING_FILE))
           {

               switch(CurrentProvider)
               {
                   case "MySQL":

                       return new ObjectSpace(
                           mappingStream,
                           ConnectionString,
                           GetMySQLProvider(),
                           20, 5);

                   case "PostgreSQL":

                       return new ObjectSpace(
                           mappingStream,
                           ConnectionString,
                           GetPostgreSQLProvider(),
                           20, 5);

                   // TODO: Oracle?

                   default:

                       return new ObjectSpace(
                           mappingStream,
                           ConnectionString,
                           Provider.MsSql,
                           20, 5);

               }

           }
       }

       #endregion

       #region private static CustomProvider GetMySQLProvider()

       private static CustomProvider GetMySQLProvider()
       {
           //Provider provider;
           CustomProvider provider;
           provider=new CustomProvider("MySql.Data", "MySql.Data.MySqlClient.MySqlConnection", "MySql.Data.MySqlClient.MySqlDataAdapter");
           provider.StartDelimiter="";
           provider.EndDelimiter="";
           provider.LineTerminator=";";
           provider.IdentityQuery= "SELECT LAST_INSERT_ID()";
           provider.SelectPageQuery="SELECT * LIMIT {0} OFFSET {1}";
           provider.ParameterPrefix = "?";
           provider.GuidDelimiter = "'";

           return provider;

       }

       #endregion

       #region private static CustomProvider GetPostgreSQLProvider()

       private static CustomProvider GetPostgreSQLProvider()
       {
           // Npgsql, the .NET provider for PostgreSQL can be found here:
           // http://pgfoundry.org/projects/npgsql

           CustomProvider provider;
           provider=new CustomProvider("Npgsql", "Npgsql.NpgsqlConnection", "Npgsql.NpgsqlDataAdapter");
           provider.StartDelimiter="[";
           provider.EndDelimiter="]";
           provider.LineTerminator=";";
           provider.IdentityQuery= "SELECT currval('{1}_{0}_seq')";
           provider.SelectPageQuery="SELECT * LIMIT {0} OFFSET {1}";
           provider.ParameterPrefix = ":";
           //not sure about this
           provider.GuidDelimiter = "'";

           return provider;

       }

       #endregion
   }
}

Components | Wilson O/R Mapper

Wednesday, February 22, 2006 8:43:01 PM (Central Standard Time, UTC-06:00)