Does Dapper support SQL 2008 Table-Valued Parameters?

Question

Does anyone know if is possible to pass table-valued parameter data to a stored procedure with Dapper?

Answer 1

There is now (n Dapper 1.26 and higher) direct support for table-valued parameters baked into dapper. In the case of stored procedures, since the data type is built into the sproc API, all you need to do is supply a DataTable:

var data = connection.Query<SomeType>(..., new {
    id=123, name="abc", values = someTable
}, ...);

For direct command-text you have two other options:

• use a helper method to tell it the custom data type:

  var data = connection.Query<SomeType>(..., new {
      id=123, name="abc", values = someTable.AsTableValuedParameter("mytype")
  }, ...);
  

• tell the data-table itself what custom data type to use:

  someTable.SetTypeName("mytype");
  var data = connection.Query<SomeType>(..., new {
      id=123, name="abc", values = someTable
  }, ...);        
  

Any of these should work fine.

Answer 2

Yes, we support them but you will need to code your own helpers.

For example:

class IntDynamicParam : Dapper.SqlMapper.IDynamicParameters
{
    IEnumerable<int> numbers;
    public IntDynamicParam(IEnumerable<int> numbers)
    {
        this.numbers = numbers;
    }

    public void AddParameters(IDbCommand command)
    {
        var sqlCommand = (SqlCommand)command;
        sqlCommand.CommandType = CommandType.StoredProcedure;

        List<Microsoft.SqlServer.Server.SqlDataRecord> number_list = new List<Microsoft.SqlServer.Server.SqlDataRecord>();

        // Create an SqlMetaData object that describes our table type.
        Microsoft.SqlServer.Server.SqlMetaData[] tvp_definition = { new Microsoft.SqlServer.Server.SqlMetaData("n", SqlDbType.Int) };

        foreach (int n in numbers)
        {
            // Create a new record, using the metadata array above.
            Microsoft.SqlServer.Server.SqlDataRecord rec = new Microsoft.SqlServer.Server.SqlDataRecord(tvp_definition);
            rec.SetInt32(0, n);    // Set the value.
            number_list.Add(rec);      // Add it to the list.
        }

        // Add the table parameter.
        var p = sqlCommand.Parameters.Add("@ints", SqlDbType.Structured);
        p.Direction = ParameterDirection.Input;
        p.TypeName = "int_list_type";
        p.Value = number_list;

    }
}

// SQL Server specific test to demonstrate TVP 
public void TestTVP()
{
    try
    {
        connection.Execute("CREATE TYPE int_list_type AS TABLE (n int NOT NULL PRIMARY KEY)");
        connection.Execute("CREATE PROC get_ints @ints int_list_type READONLY AS select * from @ints");

        var nums = connection.Query<int>("get_ints", new IntDynamicParam(new int[] { 1, 2, 3 })).ToList();
        nums[0].IsEqualTo(1);
        nums[1].IsEqualTo(2);
        nums[2].IsEqualTo(3);
        nums.Count.IsEqualTo(3);
        connection.Execute("DROP PROC get_ints");
        connection.Execute("DROP TYPE int_list_type");

    }
}

Make sure you properly test performance for table valued params. When I tested this for passing int lists it was significantly slower than passing in multiple params.

I am totally not against having some SQL Server specific helpers for dapper in the contrib project, however the core dapper avoids adding vendor specific tricks where possible.

Answer 3

I know this ticket is OLD, very old, but wanted to let you know that I have published Dapper.Microsoft.Sql package, which supports generic TVPs.

https://www.nuget.org/packages/Dapper.Microsoft.Sql/

Sample use:

List<char> nums = this.connection.Query<char>(
  "get_ints", 
  new TableValuedParameter<char>(
    "@ints", "int_list_Type", new[] { 'A', 'B', 'C' })).ToList();

It is based on the original classes from Dapper test project.

Enjoy!

Answer 4

today it isn't. We actually investigated table-valed-parameters for our cheeky "in" implementation (where col in @values), but were very unimpressed by performance. However in the context of a SPROC it makes sense.

Your best bet is to log this as an issue on the project site so we can track/prioritise it. It sounds like something will be doable, though, probably similar to the DbString or DynamicParameters options.

But today? No.