NHibernate Oracle XMLType 问题

Question

我们在 oracle 10g 数据库中有一个函数，它返回一个 XMLTYPE 值。我们正在尝试使用命令对象中的 ParameterDirection.ReturnValue 从函数中获取返回值。

但是我们遇到了错误

System.Data.OracleClient.OracleException (0x80131938)：ORA-06550：第 1 行，第 27 列： PLS-00382：表达式类型错误 ORA-06550：第 1 行，第 7 列： PL/SQL：语句被忽略

如何解决？

Answer 1

自从我从事这个工作以来已经有一段时间了，目前我没有一个工作项目来验证这个问题，但是，我相信这会解决你的问题。

我解决这个问题的方法是自定义构建 nHibernate 项目。我用下面的编辑编辑了 OracleDataClientDriver.cs 文件。您应该注意，我刚刚下载了该文件的当前版本，并且在我进行修复后的过去 2 年中它略有变化。如果您从 nHibernate 存储库获取文件的当前版本，并使用我要粘贴的代码对文件进行区分，您将看到更改。我的更改位于第 26、45、82-85 行（根据我的编辑）。

修复的主题是我必须添加一个从 nHibernate 映射文件类型到 XML 的 Oracle 数据类型的映射。 Oracle 驱动程序将处理这种类型，但缺少在 nHibernate 中使用它的逻辑。以下是解决此问题的方法。

开始粘贴-----

using System.Data;
using System.Reflection;
using NHibernate.AdoNet;
using NHibernate.Engine.Query;
using NHibernate.SqlTypes;
using NHibernate.Util;

namespace NHibernate.Driver
{
    /// <summary>
    /// A NHibernate Driver for using the Oracle.DataAccess DataProvider
    /// </summary>
    /// <remarks>
    /// Code was contributed by <a href="http://sourceforge.net/users/jemcalgary/">James Mills</a>
    /// on the NHibernate forums in this 
    /// <a href="http://sourceforge.net/forum/message.php?msg_id=2952662">post</a>.
    /// </remarks>
    public class OracleDataClientDriver : ReflectionBasedDriver, IEmbeddedBatcherFactoryProvider
    {
        private const string driverAssemblyName = "Oracle.DataAccess";
        private const string connectionTypeName = "Oracle.DataAccess.Client.OracleConnection";
        private const string commandTypeName = "Oracle.DataAccess.Client.OracleCommand";
        private static readonly SqlType GuidSqlType = new SqlType(DbType.Binary, 16);
        private readonly PropertyInfo oracleDbType;
        private readonly object oracleDbTypeRefCursor; 
        private readonly object oracleDbTypeXmlType;

        /// <summary>
        /// Initializes a new instance of <see cref="OracleDataClientDriver"/>.
        /// </summary>
        /// <exception cref="HibernateException">
        /// Thrown when the <c>Oracle.DataAccess</c> assembly can not be loaded.
        /// </exception>
        public OracleDataClientDriver()
            : base(
            driverAssemblyName,
            connectionTypeName,
            commandTypeName)
        {
            System.Type parameterType = ReflectHelper.TypeFromAssembly("Oracle.DataAccess.Client.OracleParameter", driverAssemblyName, false);
            oracleDbType = parameterType.GetProperty("OracleDbType");

            System.Type oracleDbTypeEnum = ReflectHelper.TypeFromAssembly("Oracle.DataAccess.Client.OracleDbType", driverAssemblyName, false);
            oracleDbTypeRefCursor = System.Enum.Parse(oracleDbTypeEnum, "RefCursor");
            oracleDbTypeXmlType = System.Enum.Parse(oracleDbTypeEnum, "XmlType");
        }

        /// <summary></summary>
        public override bool UseNamedPrefixInSql
        {
            get { return true; }
        }

        /// <summary></summary>
        public override bool UseNamedPrefixInParameter
        {
            get { return true; }
        }

        /// <summary></summary>
        public override string NamedPrefix
        {
            get { return ":"; }
        }

        /// <remarks>
        /// This adds logic to ensure that a DbType.Boolean parameter is not created since
        /// ODP.NET doesn't support it.
        /// </remarks>
        protected override void InitializeParameter(IDbDataParameter dbParam, string name, SqlType sqlType)
        {
            // if the parameter coming in contains a boolean then we need to convert it 
            // to another type since ODP.NET doesn't support DbType.Boolean
            switch (sqlType.DbType)
            {
                case DbType.Boolean:
                    base.InitializeParameter(dbParam, name, SqlTypeFactory.Int16);
                    break;
                case DbType.Guid:
                    base.InitializeParameter(dbParam, name, GuidSqlType);
                    break;
                case DbType.Xml:
                    dbParam.ParameterName = base.FormatNameForParameter(name);
                    oracleDbType.SetValue(dbParam, oracleDbTypeXmlType, null);
                    break;
                default:
                    base.InitializeParameter(dbParam, name, sqlType);
                    break;
            }
        }

        protected override void OnBeforePrepare(IDbCommand command)
        {
            base.OnBeforePrepare(command);

            CallableParser.Detail detail = CallableParser.Parse(command.CommandText);

            if (!detail.IsCallable)
                return;

            command.CommandType = CommandType.StoredProcedure;
            command.CommandText = detail.FunctionName;

            IDbDataParameter outCursor = command.CreateParameter();
            oracleDbType.SetValue(outCursor, oracleDbTypeRefCursor, null);

            outCursor.Direction = detail.HasReturn ? ParameterDirection.ReturnValue : ParameterDirection.Output;

            command.Parameters.Insert(0, outCursor);
        }

        #region IEmbeddedBatcherFactoryProvider Members

        System.Type IEmbeddedBatcherFactoryProvider.BatcherFactoryClass
        {
            get { return typeof (OracleDataClientBatchingBatcherFactory); }
        }

        #endregion
    }

结束粘贴-------