How to generate model from database using Dapper?

Question

I am coming from PetaPoco camp. PetaPoco has a T4 template which generates model from the database. Is anything similar available for Dapper?

I installed Dapper using NuGet and added SqlHelper.cs, but I didn't find anything which generates model from the database.

Answer 1

Calling the stored procedure from a cursor

If you combine the sp mattritchies mentioned (see answer above) and call it from a cursor you can generate the poco class for every table in your database

USE YourDataBaseName
GO 
    DECLARE @field1 nvarchar(400)
    DECLARE cur CURSOR LOCAL for

    SELECT TABLE_NAME FROM information_schema.tables
    OPEN cur
    FETCH NEXT FROM cur INTO @field1 --, @field2
    WHILE @@FETCH_STATUS = 0 BEGIN          
        exec Helper_CreatePocoFromTableName @field1 -- , @field2            
        fetch next from cur into @field1 -- , @field2
    END

close cur
deallocate cur

Stored Procedure mattritchies mentioned

I took the sql from mattritchies answer (see above) and created the stored procedure he mentioned and modified it a bit so that it adds the class name as well. If you put Management Studio into Text-Output-Mode and remove the output of the column names you get copy paste text for all classes:

CREATE PROCEDURE [dbo].[Helper_CreatePocoFromTableName]    
    @tableName varchar(100)
AS
BEGIN
SET NOCOUNT ON;

-- Subquery to return only the copy paste text
Select PropertyColumn from (
    SELECT 1 as rowNr, 'public class ' + @tableName + ' {' as PropertyColumn
    UNION
    SELECT 2 as rowNr, 'public ' + a1.NewType + ' ' + a1.COLUMN_NAME + ' {get;set;}' as PropertyColumn
    -- ,* comment added so that i get copy pasteable output
     FROM 
    (
        /*using top because i'm putting an order by ordinal_position on it. 
        putting a top on it is the only way for a subquery to be ordered*/
        SELECT TOP 100 PERCENT
        COLUMN_NAME,
        DATA_TYPE,
        IS_NULLABLE,
        CASE 
            WHEN DATA_TYPE = 'varchar' THEN 'string'
            WHEN DATA_TYPE = 'nvarchar' THEN 'string' 
            WHEN DATA_TYPE = 'datetime' AND IS_NULLABLE = 'NO' THEN 'DateTime'
            WHEN DATA_TYPE = 'datetime' AND IS_NULLABLE = 'YES' THEN 'DateTime?'
            WHEN DATA_TYPE = 'smalldatetime' AND IS_NULLABLE = 'NO' THEN 'DateTime'
            WHEN DATA_TYPE = 'datetime2' AND IS_NULLABLE = 'NO' THEN 'DateTime'
            WHEN DATA_TYPE = 'smalldatetime' AND IS_NULLABLE = 'YES' THEN 'DateTime?'
            WHEN DATA_TYPE = 'datetime2' AND IS_NULLABLE = 'YES' THEN 'DateTime?'
            WHEN DATA_TYPE = 'int' AND IS_NULLABLE = 'YES' THEN 'int?'
            WHEN DATA_TYPE = 'int' AND IS_NULLABLE = 'NO' THEN 'int'
            WHEN DATA_TYPE = 'smallint' AND IS_NULLABLE = 'NO' THEN 'Int16'
            WHEN DATA_TYPE = 'smallint' AND IS_NULLABLE = 'YES' THEN 'Int16?'
            WHEN DATA_TYPE = 'decimal' AND IS_NULLABLE = 'NO' THEN 'decimal'
            WHEN DATA_TYPE = 'decimal' AND IS_NULLABLE = 'YES' THEN 'decimal?'
            WHEN DATA_TYPE = 'numeric' AND IS_NULLABLE = 'NO' THEN 'decimal'
            WHEN DATA_TYPE = 'numeric' AND IS_NULLABLE = 'YES' THEN 'decimal?'
            WHEN DATA_TYPE = 'money' AND IS_NULLABLE = 'NO' THEN 'decimal'
            WHEN DATA_TYPE = 'money' AND IS_NULLABLE = 'YES' THEN 'decimal?'
            WHEN DATA_TYPE = 'bigint' AND IS_NULLABLE = 'NO' THEN 'long'
            WHEN DATA_TYPE = 'bigint' AND IS_NULLABLE = 'YES' THEN 'long?'
            WHEN DATA_TYPE = 'tinyint' AND IS_NULLABLE = 'NO' THEN 'byte'
            WHEN DATA_TYPE = 'tinyint' AND IS_NULLABLE = 'YES' THEN 'byte?'
            WHEN DATA_TYPE = 'char' THEN 'string'                       
            WHEN DATA_TYPE = 'timestamp' THEN 'byte[]'
            WHEN DATA_TYPE = 'varbinary' THEN 'byte[]'
            WHEN DATA_TYPE = 'bit' AND IS_NULLABLE = 'NO' THEN 'bool'
            WHEN DATA_TYPE = 'bit' AND IS_NULLABLE = 'YES' THEN 'bool?'
            WHEN DATA_TYPE = 'xml' THEN 'string'
        END AS NewType
        FROM INFORMATION_SCHEMA.COLUMNS 
        WHERE TABLE_NAME = @tableName
        ORDER BY ORDINAL_POSITION
        ) AS a1 
    UNION 
    SELECT 3 as rowNr,  '} // class ' + @tableName
    ) as t Order By rowNr asc
END

P.S.: I would have done it as an edit suggestion to his answers but my experience is that often edit suggestions get rejected.

Update

User chris-w-mclean suggested the following changes (see his suggested-edit) which i have not tried myself:

• Replace SELECT 1 as rowNr, 'public class ' with SELECT 1.0 as rowNr, 'public class '
• Replace SELECT 2 as rowNr, 'public ' with SELECT 2 + a1.ORDINAL_POSITION/1000 as rowNr, 'public '
• Replace SELECT TOP 100 PERCENT COLUMN_NAME, with SELECT COLUMN_NAME,
• add between IS_NULLABLE, CASE this line cast(ORDINAL_POSITION as float) as ORDINAL_POSITION,
• remove ORDER BY ORDINAL_POSITION
• change SELECT 3 as to SELECT 3.0 as

Answer 2

Try this version I optimized a bit, so that the result doesn't need to be piped to Text output. Instead, the PRINT statement allows the output to be copy/pasted easily. I've also removed the subquery and added declarations for nvarchar/ntext types.

This is for a single table, but it can be converted to a stored proc to use one of the cursor suggestions above.

SET NOCOUNT ON
DECLARE @tbl as varchar(255)
SET @tbl = '@@@@'

DECLARE @flds as varchar(8000)
SET @flds=''

SELECT -1 as f0, 'public class ' + @tbl + ' {' as f1 into #tmp

INSERT #tmp
SELECT 
    ORDINAL_POSITION, 
    '    public ' + 
    CASE 
        WHEN DATA_TYPE = 'varchar' THEN 'string'
        WHEN DATA_TYPE = 'nvarchar' THEN 'string'
        WHEN DATA_TYPE = 'text' THEN 'string'
        WHEN DATA_TYPE = 'ntext' THEN 'string'
        WHEN DATA_TYPE = 'char' THEN 'string'
        WHEN DATA_TYPE = 'xml' THEN 'string'
        WHEN DATA_TYPE = 'datetime' AND IS_NULLABLE = 'NO' THEN 'DateTime'
        WHEN DATA_TYPE = 'datetime' AND IS_NULLABLE = 'YES' THEN 'DateTime?'
        WHEN DATA_TYPE = 'int' AND IS_NULLABLE = 'YES' THEN 'int?'
        WHEN DATA_TYPE = 'int' AND IS_NULLABLE = 'NO' THEN 'int'
        WHEN DATA_TYPE = 'smallint' AND IS_NULLABLE = 'NO' THEN 'Int16'
        WHEN DATA_TYPE = 'smallint' AND IS_NULLABLE = 'YES' THEN 'Int16?'
        WHEN DATA_TYPE = 'decimal' AND IS_NULLABLE = 'NO' THEN 'decimal'
        WHEN DATA_TYPE = 'decimal' AND IS_NULLABLE = 'YES' THEN 'decimal?'
        WHEN DATA_TYPE = 'numeric' AND IS_NULLABLE = 'NO' THEN 'decimal'
        WHEN DATA_TYPE = 'numeric' AND IS_NULLABLE = 'YES' THEN 'decimal?'
        WHEN DATA_TYPE = 'money' AND IS_NULLABLE = 'NO' THEN 'decimal'
        WHEN DATA_TYPE = 'money' AND IS_NULLABLE = 'YES' THEN 'decimal?'
        WHEN DATA_TYPE = 'bigint' AND IS_NULLABLE = 'NO' THEN 'long'
        WHEN DATA_TYPE = 'bigint' AND IS_NULLABLE = 'YES' THEN 'long?'
        WHEN DATA_TYPE = 'tinyint' AND IS_NULLABLE = 'NO' THEN 'byte'
        WHEN DATA_TYPE = 'tinyint' AND IS_NULLABLE = 'YES' THEN 'byte?'
        WHEN DATA_TYPE = 'timestamp' THEN 'byte[]'
        WHEN DATA_TYPE = 'varbinary' THEN 'byte[]'
        WHEN DATA_TYPE = 'bit' AND IS_NULLABLE = 'NO' THEN 'bool'
        WHEN DATA_TYPE = 'bit' AND IS_NULLABLE = 'YES' THEN 'bool?'
    END + ' ' + COLUMN_NAME + ' {get;set;}'
FROM INFORMATION_SCHEMA.COLUMNS 
        WHERE TABLE_NAME = @tbl

INSERT #tmp SELECT 999, '}'

SELECT @flds=@flds + f1 +'
' from #tmp order by f0

DROP TABLE #tmp

PRINT @flds

Answer 3

Dapper itself provides few extension methods (Query, Execute) for the connection object and does not have "model generator." Perhaps some other framework can be used to generate POCO's based on the db schema.

Update:

Database tables to C# POCO classes T4 template

<#@ template language="C#" debug="True" #>

<#@ assembly name="System" #>
<#@ assembly name="System.Data" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="System.Xml" #>

<#@ assembly name="Microsoft.SqlServer.ConnectionInfo" #>
<#@ assembly name="Microsoft.SqlServer.Management.Sdk.Sfc" #>
<#@ assembly name="Microsoft.SqlServer.Smo" #>

<#@ import namespace="System" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Xml" #>
<#@ import namespace="Microsoft.SqlServer.Management.Smo" #>
<#@ import namespace="System.Data.SqlClient" #>
<#@ import namespace="Microsoft.SqlServer.Management.Common" #>

namespace Namespace
{

<#         
   var databaseName = "testDb";
            var serverConnection = new SqlConnection(
                    @"Data Source=.\SQLEXPRESS; Integrated Security=true; Initial Catalog=" + databaseName);
            var svrConnection = new ServerConnection(serverConnection);

   Server srv = new Server(svrConnection);
            foreach (Table table in srv.Databases[databaseName].Tables)
            {

#>
        class <#= table.Name #>
        {
            <#
                foreach (Column col in table.Columns)
                {
                #>
                    public <#= GetNetDataType(col.DataType.Name) #> <#= col.Name #> { get; set; }
                <#
                }
             #>
        }

<#            }
#>
}



<#+
        public static string GetNetDataType(string sqlDataTypeName)
        {

            switch (sqlDataTypeName.ToLower())
            {
                case "bigint":
                    return "Int64";
                case "binary":
                    return "Byte[]";
                case "bit":
                    return "bool";
                case "char":
                    return "char";
                case "cursor":
                    return string.Empty;
                case "datetime":
                    return "DateTime";
                case "decimal":
                    return "Decimal";
                case "float":
                    return "Double";
                case "int":
                    return "int";
                case "money":
                    return "Decimal";
                case "nchar":
                    return "string";
                case "numeric":
                    return "Decimal";
                case "nvarchar":
                    return "string";
                case "real":
                    return "single";
                case "smallint":
                    return "Int16";
                case "text":
                    return "string";
                case "tinyint":
                    return "Byte";
                case "varbinary":
                    return "Byte[]";
                case "xml":
                    return "string";
                case "varchar":
                    return "string";
                case "smalldatetime":
                    return "DateTime";
                case "image":
                    return "byte[]";

                default:
                    return string.Empty;
            }



        }
#>

Answer 4

I've just recently written a sql query to do the job for myself. And updating it with extra types when i need. Just replace the table name where it says @@@@.

To make alot of tables i created a temp stored procedure to call. eg. exec createTablePOCO(@tableName)

SELECT 
'public ' + a1.NewType + ' ' + a1.COLUMN_NAME + ' {get;set;}'
,*
 FROM 
(
/*using top because i'm putting an order by ordinal_position on it. 
putting a top on it is the only way for a subquery to be ordered*/
SELECT TOP 100 PERCENT
COLUMN_NAME,
DATA_TYPE,
IS_NULLABLE,
CASE 
    WHEN DATA_TYPE = 'varchar' THEN 'string'
    WHEN DATA_TYPE = 'datetime' AND IS_NULLABLE = 'NO' THEN 'DateTime'
    WHEN DATA_TYPE = 'datetime' AND IS_NULLABLE = 'YES' THEN 'DateTime?'
    WHEN DATA_TYPE = 'int' AND IS_NULLABLE = 'YES' THEN 'int?'
    WHEN DATA_TYPE = 'int' AND IS_NULLABLE = 'NO' THEN 'int'
    WHEN DATA_TYPE = 'smallint' AND IS_NULLABLE = 'NO' THEN 'Int16'
    WHEN DATA_TYPE = 'smallint' AND IS_NULLABLE = 'YES' THEN 'Int16?'
    WHEN DATA_TYPE = 'decimal' AND IS_NULLABLE = 'NO' THEN 'decimal'
    WHEN DATA_TYPE = 'decimal' AND IS_NULLABLE = 'YES' THEN 'decimal?'
    WHEN DATA_TYPE = 'numeric' AND IS_NULLABLE = 'NO' THEN 'decimal'
    WHEN DATA_TYPE = 'numeric' AND IS_NULLABLE = 'YES' THEN 'decimal?'
    WHEN DATA_TYPE = 'money' AND IS_NULLABLE = 'NO' THEN 'decimal'
    WHEN DATA_TYPE = 'money' AND IS_NULLABLE = 'YES' THEN 'decimal?'
    WHEN DATA_TYPE = 'bigint' AND IS_NULLABLE = 'NO' THEN 'long'
    WHEN DATA_TYPE = 'bigint' AND IS_NULLABLE = 'YES' THEN 'long?'
    WHEN DATA_TYPE = 'tinyint' AND IS_NULLABLE = 'NO' THEN 'byte'
    WHEN DATA_TYPE = 'tinyint' AND IS_NULLABLE = 'YES' THEN 'byte?'
    WHEN DATA_TYPE = 'char' THEN 'string'
    WHEN DATA_TYPE = 'timestamp' THEN 'byte[]'
    WHEN DATA_TYPE = 'varbinary' THEN 'byte[]'
    WHEN DATA_TYPE = 'bit' AND IS_NULLABLE = 'NO' THEN 'bool'
    WHEN DATA_TYPE = 'bit' AND IS_NULLABLE = 'YES' THEN 'bool?'
    WHEN DATA_TYPE = 'xml' THEN 'string'
END AS NewType
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = '@@@@'
ORDER BY ORDINAL_POSITION
) AS a1

Answer 5

Here's dapper-pocos I made for generating POCOs for Dapper. The solution uses SQL Server's "sp_HELP" and "sp_describe_first_result_set". Give it the name of a stored procedure, or give it a select statement, and it will generate the related POCOs for use with Dapper. The app just passes the stored procedure or select statement to sp_Help and sp_describe_first_result_set, and maps the results to C# data types.