Using Dapper with Oracle User-Defined Types

Question

Is there a way to use Dapper with Oracle User-Defined Types returned by stored procedures? Dapper seems to work with stored procedures (see Using Dapper with Oracle stored procedures which return cursors).

var p = new OracleDynamicParameters();
p.Add("param_list", null, OracleDbType.Object, ParameterDirection.Output);
p.Add("param_reco", null, OracleDbType.Object, ParameterDirection.Output);

In my example I've added a UDT collection object as output parameter (param_list). I'm using the custom OracleDynamicParameters posted in Dapper – Micro ORM for Oracle and Microsoft .NET.

The more I read ORM related stuff, the more I see Oracle UDT objects as an obstacle. In this case plain ADO.NET and generated C# entity classes seem to be the only way to go. Maybe automapper.org might be useful for mapping domain objects to UDT objects.

Answer 1

Look into using OracleCustomTypeMapping attribute and the OracleObjectMapping attribute. Can't recall where I got this idea from but...

public interface INullableOracleCustomType: INullable,  IOracleCustomType
    {
    }

[OracleCustomTypeMapping("<YOUR_SCHEMA_NAME>.<UDT_OBJECT_NAME>")]
    public class ParameterObject : INullableOracleCustomType
    {
        private bool objectIsNull;

        #region constructor

        public ParameterObject()
        { }

        public ParameterObject(string parameterName, string parameterValue)
        {
            this.ParameterName = parameterName;
            this.ParameterValue = parameterValue;
        }

        #endregion

        #region properties
        [OracleObjectMappingAttribute("PARAMETERNAME")]
        public string ParameterName { get; set; }

        [OracleObjectMappingAttribute("PARAMETERVALUE")]
        public string ParameterValue { get; set; }

        public static ParameterObject Null
        {
            get
            {
                ParameterObject parameterObject = new ParameterObject();
                parameterObject.objectIsNull = true;
                return parameterObject;
            }
        }

        #endregion

        #region INullable Members

        public bool IsNull
        {
            get { return objectIsNull; }
        }

        #endregion

        #region IOracleCustomType
        public void FromCustomObject(Oracle.DataAccess.Client.OracleConnection con, IntPtr pUdt)
        {
            // Convert from the Custom Type to Oracle Object
            if (!string.IsNullOrEmpty(ParameterName))
            {
                OracleUdt.SetValue(con, pUdt, "PARAMETERNAME", ParameterName);
            }
            if (!string.IsNullOrEmpty(ParameterValue))
            {
                OracleUdt.SetValue(con, pUdt, "PARAMETERVALUE", ParameterValue);
            }
        }

        public void ToCustomObject(Oracle.DataAccess.Client.OracleConnection con, IntPtr pUdt)
        {
            ParameterName = (string)OracleUdt.GetValue(con, pUdt, "PARAMETERNAME");
            ParameterValue = (string)OracleUdt.GetValue(con, pUdt, "PARAMETERVALUE");
        }

        #endregion
    }

example usage ...

public static OracleParameter CreateCustomTypeArrayInputParameter<T>(string name, string oracleUDTName, T value)
            where T : INullableOracleCustomType
        {
            OracleParameter parameter = new OracleParameter();
            parameter.ParameterName = name;
            parameter.OracleDbType = OracleDbType.Array;
            parameter.Direction = ParameterDirection.Input;
            parameter.UdtTypeName = oracleUDTName;
            parameter.Value = value;
            return parameter;
        }

Oracle seems fussy about the schema/type/object names being in ALLCAPS