Entity Framework CTP 4 - Code First Custom Database Initializer

Question

I would like to implement a custom database initialization strategy so that I can generate the database schema and apply it to an EXISTING EMPTY SQL database using a supplie

Answer 1

I too was looking for a good solution since godaddy does not allow drop/creation of database and thus no tables created. Since the newer version of Entity Framework has obsoleted EDMData, I modified Alex's code to see if a DropMeToRecreateDatabase table exists or not, if it doesnt exist, it deletes all tables and recreates new tables.

using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Objects;
using System.Linq;

namespace LadyTreble.DatabaseInitializer
{

    public class DontDropExistingDbCreateTablesIfTableDropped : IDatabaseInitializer where T : DbContext
    {
        public bool TryInitializeDatabase(T context)
        {
            var objectContext = ((IObjectContextAdapter)context).ObjectContext;
            if (objectContext.ExecuteStoreQuery(GetTableCount).FirstOrDefault() == 0)
            {
                this.DeleteExistingTables(objectContext);
                this.CreateTables(objectContext);
            }
            return true;
        }

        public void InitializeDatabase(T context)
        {
            this.TryInitializeDatabase(context);
        }

        private void CreateTables(ObjectContext objectContext)
        {
            string dataBaseCreateScript = objectContext.CreateDatabaseScript();
            objectContext.ExecuteStoreCommand(dataBaseCreateScript);
        }

        private void DeleteExistingTables(ObjectContext objectContext)
        {

            objectContext.ExecuteStoreCommand(DeleteAllTablesScript);
        }

        private const string DeleteAllTablesScript =
            @"declare @cmd varchar(4000)

              DECLARE cmds0 CURSOR FOR 
              SELECT 'ALTER TABLE ' + TABLE_NAME + ' DROP CONSTRAINT ' + CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'

              DECLARE cmds1 CURSOR FOR 
              SELECT 'ALTER TABLE ' + TABLE_NAME + ' DROP CONSTRAINT ' + CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS

              DECLARE cmds2 CURSOR FOR 
              SELECT 'TRUNCATE TABLE ' + TABLE_NAME FROM INFORMATION_SCHEMA.TABLES

              DECLARE cmds3 CURSOR FOR 
              SELECT 'DROP TABLE [' + TABLE_NAME + ']' FROM INFORMATION_SCHEMA.TABLES

              open cmds0
              while 1=1
              begin
                  fetch cmds0 into @cmd
                  if @@fetch_status != 0 break
                  print @cmd
                  exec(@cmd)
              end
              close cmds0
              deallocate cmds0

              open cmds1
              while 1=1
              begin
                  fetch cmds1 into @cmd
                  if @@fetch_status != 0 break
                  print @cmd
                  exec(@cmd)
              end
              close cmds1
              deallocate cmds1

              open cmds2
              while 1=1
              begin
                  fetch cmds2 into @cmd
                  if @@fetch_status != 0 break
                  print @cmd
                  exec(@cmd)
              end
              close cmds2
              deallocate cmds2

              open cmds3
              while 1=1
              begin
                  fetch cmds3 into @cmd
                  if @@fetch_status != 0 break
                  print @cmd
                  exec(@cmd)
              end
              close cmds3
              deallocate cmds3

             CREATE TABLE DropMeToRecreateDatabase(id int IDENTITY(1,1) NOT NULL)";

        private const string GetTableCount =
            @"SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES T WHERE T.TABLE_NAME = 'DropMeToRecreateDatabase'";
    }

}