Generate Dart Classes from table or Views

GenerateClass.sql

CREATE OR ALTER PROCEDURE [dbo].[GenerateDartClass] (@TableName sysname = null)
AS
BEGIN
    DECLARE @Result VARCHAR(MAX) = ''

    DECLARE the_cursor CURSOR FAST_FORWARD
    FOR
    SELECT TABLE_NAME
    FROM INFORMATION_SCHEMA.TABLES
    WHERE (TABLE_TYPE = 'BASE TABLE' OR TABLE_TYPE = 'VIEW') AND ISNULL(@TableName, TABLE_NAME) = TABLE_NAME
    ORDER BY TABLE_TYPE, TABLE_NAME
    OPEN the_cursor
    FETCH NEXT FROM the_cursor INTO @TableName

    WHILE @@FETCH_STATUS = 0
    BEGIN
        SET @Result = @Result + '
	/// Class for ' + @TableName + '
	class ' + REPLACE(REPLACE(REPLACE(@TableName, ' ', '_'), '.', '_'), '~', '_') + '
	{
		///Table Name
		const String SQLTableName = "[' + @TableName + ']";

		///DataBase Name
		const String SQLDataBaseName = "[' + DB_NAME() + ']";

		///Return a SELECT Query for ' + @TableName + '
		String get query => "SELECT * FROM " + SQLDataBaseName + "." + SQLTableName;

		///Return a SELECT Query for ' + @TableName + '
		@override
		String ToString() => getQuery();

		/// Convert from JSON Map to ' + @TableName + ' object
		factory ' + REPLACE(REPLACE(REPLACE(@TableName, ' ', '_'), '.', '_'), '~', '_') + '.fromJson(Map<String, dynamic> json) {
			return ' + REPLACE(REPLACE(REPLACE(@TableName, ' ', '_'), '.', '_'), '~', '_') + '(
				' + STUFF((
                    SELECT ',
				json["' + ColumnName + '"] as ' + ColumnName
                    FROM
                        (
                            SELECT
                                REPLACE(REPLACE(REPLACE(col.name, ' ', '_'), '.', '_'), '~', '_') ColumnName,
                                column_id ColumnId
                            FROM sys.columns col
                            WHERE object_id = OBJECT_ID(@TableName)
                        ) t
                    ORDER BY ColumnId
                    FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 1, '') + '
			);
		}

		/// Convert from ' + @TableName + ' object to JSON Map
		Map<String, dynamic> toJson() {
			return {
				' + STUFF((
                    SELECT ',
				"' + ColumnName + '": this.' + ColumnName
                    FROM
                        (
                            SELECT
                                REPLACE(REPLACE(REPLACE(col.name, ' ', '_'), '.', '_'), '~', '_') ColumnName,
                                column_id ColumnId
                            FROM sys.columns col
                            WHERE object_id = OBJECT_ID(@TableName)
                        ) t
                    ORDER BY ColumnId
                    FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 1, '') + '
			};
		}
		' + STUFF((
                SELECT '
		///Name: [' + ColumnName + '] | Type: ' + ColumnType + ' | Scale: ' + CAST(scale AS VARCHAR) + ' | Precision: ' + CAST(precision AS VARCHAR) + ' | Max Length: ' + CAST(max_length AS VARCHAR) + ' | Allow Null: ' + IIF(is_nullable = 1, 'Yes', 'No') + '
		public ' + ColumnType + NullableSign + ' ' + ColumnName + ';' + '
		'
                FROM
                    (
                        SELECT
                            REPLACE(REPLACE(REPLACE(col.name, ' ', '_'), '.', '_'), '~', '_') ColumnName,
                            column_id ColumnId,
                            CASE typ.name
                                WHEN 'bigint' THEN 'int'
                                WHEN 'binary' THEN 'List<int>'
                                WHEN 'bit' THEN 'bool'
                                WHEN 'char' THEN 'String'
                                WHEN 'date' THEN 'DateTime'
                                WHEN 'datetime' THEN 'DateTime'
                                WHEN 'datetime2' THEN 'DateTime'
                                WHEN 'datetimeoffset' THEN 'DateTime'
                                WHEN 'decimal' THEN 'double'
                                WHEN 'float' THEN 'double'
                                WHEN 'image' THEN 'List<int>'
                                WHEN 'int' THEN 'int'
                                WHEN 'money' THEN 'double'
                                WHEN 'nchar' THEN 'String'
                                WHEN 'ntext' THEN 'String'
                                WHEN 'numeric' THEN 'double'
                                WHEN 'nvarchar' THEN 'String'
                                WHEN 'real' THEN 'double'
                                WHEN 'smalldatetime' THEN 'DateTime'
                                WHEN 'smallint' THEN 'int'
                                WHEN 'smallmoney' THEN 'double'
                                WHEN 'text' THEN 'String'
                                WHEN 'time' THEN 'Duration'
                                WHEN 'timestamp' THEN 'int'
                                WHEN 'tinyint' THEN 'int'
                                WHEN 'uniqueidentifier' THEN 'String'
                                WHEN 'varbinary' THEN 'List<int>'
                                WHEN 'varchar' THEN 'String'
                                ELSE 'dynamic'
                            END ColumnType,
                            CASE
                                WHEN col.is_nullable = 1 THEN '?'
                                ELSE ''
                            END NullableSign,
                            col.scale,
                            col.precision,
                            col.is_nullable,
                            col.max_length
                        FROM sys.columns col
                        JOIN sys.types typ ON col.system_type_id = typ.system_type_id AND col.user_type_id = typ.user_type_id
                        WHERE object_id = OBJECT_ID(@TableName)
                    ) t
                ORDER BY ColumnId
                FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 1, '') + '
	}'

        FETCH NEXT FROM the_cursor INTO @TableName

    END

    CLOSE the_cursor
    DEALLOCATE the_cursor

    SET @Result = @Result + '

}'

    PRINT @result
    SELECT @Result
END