Sql Server Compact dialect provider for OrmLite

SqlCeOrmLiteDialectProvider.cs

using System;
using System.IO;
using System.Collections.Generic;
using System.Data.SqlServerCe;
using ServiceStack.OrmLite.SqlServer;

namespace Slyngelstat.OrmLite.SqlCe
{
    public class SqlCeOrmLiteDialectProvider : SqlServerOrmLiteDialectProvider
    {
        public SqlCeOrmLiteDialectProvider()
        {
            // Sql Ce only supports NVARCHAR's with a length of up to 4000 (VARCHAR not supported)
            // "GetColumnDefinition" will change this to NTEXT when creating a table with a string column larger that 4000
            base.DefaultStringLength = 4000;
            base.StringColumnDefinition = "NVARCHAR(4000)";
            base.StringLengthColumnDefinitionFormat = "NVARCHAR({0})";
            base.StringLengthNonUnicodeColumnDefinitionFormat = "NVARCHAR({0})";
            base.StringLengthUnicodeColumnDefinitionFormat = "NVARCHAR({0})";

            // Sql Ce only supports blob with a length up to 8000
            // "GetColumnDefinition" will change this to IMAGE when creating a table with a blob column larger that 8000
            base.BlobColumnDefinition = "VARBINARY(8000)";

            base.InitColumnTypeMap();
        }

        public override System.Data.IDbConnection CreateConnection(string connectionString, Dictionary<string, string> options)
        {
            if (options != null)
            {
                SqlCeConnectionStringBuilder builder = new SqlCeConnectionStringBuilder(connectionString);

                foreach (var option in options)
                {
                    if (option.Key.ToLower() == "read only")
                    {
                        if (option.Value.ToLower() == "true")
                        {
                            builder.FileMode = "Read Only";

                            // Sql Ce requires a temp path when in read only mode. 
                            // But OrmLite can not provide the temp path so we need to roll our own, 
                            // setting it to the path where the db file is
                            builder.TempFilePath = new FileInfo(builder.DataSource).Directory.FullName;
                        }
                    }
                    else
                    {
                        builder.Add(option.Key, option.Value);
                    }
                }

                return new SqlCeConnection(builder.ConnectionString);
            }

            return new SqlCeConnection(connectionString);
        }

        public override string GetColumnDefinition(string fieldName, Type fieldType, bool isPrimaryKey, bool autoIncrement, bool isNullable, int? fieldLength, int? scale, string defaultValue)
        {
            string defaultColumnDefinition = base.GetColumnDefinition(fieldName, fieldType, isPrimaryKey, autoIncrement, isNullable, fieldLength, scale, defaultValue);

            if (fieldLength.HasValue)
            {
                if (fieldType == typeof(string) && fieldLength > 4000)
                {
                    // NVARCHAR greater than 4000 is not supported in Sql Ce so use NTEXT
                    return defaultColumnDefinition.Replace(string.Format(base.StringLengthColumnDefinitionFormat, fieldLength), "NTEXT");
                }

                if (fieldType == typeof(byte[]) && fieldLength > 8000)
                {
                    // VARBINARY greater than 8000 is not supported in Sql Ce so use IMAGE
                    return defaultColumnDefinition.Replace("VARBINARY(8000)", "IMAGE");
                }
            }

            return defaultColumnDefinition;
        }

        public override long GetLastInsertId(System.Data.IDbCommand dbCmd)
        {
            // Sql Ce does not support SCOPE_IDENTITY();
            dbCmd.CommandText = "SELECT @@IDENTITY";
            object result = dbCmd.ExecuteScalar();
            if (result is DBNull)
            {
                return 0L;
            }
            if (result is decimal)
            {
                return Convert.ToInt64((decimal)result);
            }
            return (long)result;
        }
    }
}