Question

我收到以下行的错误 returnMessage = ((command.Parameters[4].Value);

实际上，我的代码通过使用Oracle存储过程将各种类型的List数组作为参数传递给Oracle。代码

List<string> AccNo = new List<string>();
List<Double> TrnAmt = new List<Double>();
List<int> TranNo = new List<int>();
List<string> rec = new List<string>();

AccNo.Add(data_read3[3].ToString());
TrnAmt.Add( Double.Parse(data_read3[0].ToString()));
TranNo.Add(trnno);

rec = cn_new.Call_Procedure_Host("Host_to_Host.host_record", AccNo, TrnAmt, 
TranNo, CONNECTION_STRING_other);

现在Call_Procedure_Host将返回参数，该参数也是一个数组列表。给出的代码

public List<string> Call_Procedure_Host(string a, List<string> b, List<double> c, List<int> d,string cn)
{
    OracleParameter op = null;
    try
    {

        connection.Close();
        connection.ConnectionString = cn;
        connection.Open();
        OracleCommand command = connection.CreateCommand();
        command.CommandText = a;
        command.CommandType = CommandType.StoredProcedure;

        var arry = command.Parameters.Add("Accno", OracleDbType.Varchar2);
        //op = new OracleParameter("Accno", OracleDbType.Varchar2);
        arry.Direction = ParameterDirection.Input;
        arry.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
        arry.Value = b.ToArray();
        arry.Size = b.Count();
        arry.ArrayBindSize = b.Select(_ => _.Length).ToArray();
        arry.ArrayBindStatus = Enumerable.Repeat(OracleParameterStatus.Success, b.Count()).ToArray();
        //op.Value = b;
        //command.Parameters.Add(op);


        var arry1 = command.Parameters.Add("Trnamount", OracleDbType.Double);
        //op = new OracleParameter("Accno", OracleDbType.Varchar2);
        arry1.Direction = ParameterDirection.Input;
        arry1.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
        arry1.Value = c.ToArray();
        arry1.Size = c.Count();
        arry1.ArrayBindSize = c.Select(_ => _.ToString().Length).ToArray();
        arry1.ArrayBindStatus = Enumerable.Repeat(OracleParameterStatus.Success, c.Count()).ToArray();
        //op.Value = b;
        //command.Parameters.Add(op);

        var arry2 = command.Parameters.Add("Trnno", OracleDbType.Int32);
        //op = new OracleParameter("Accno", OracleDbType.Varchar2);
        arry2.Direction = ParameterDirection.Input;
        arry2.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
        arry2.Value = d.ToArray();
        arry2.Size = d.Count();
        arry2.ArrayBindSize = d.Select(_ => _.ToString().Length).ToArray();
        arry2.ArrayBindStatus = Enumerable.Repeat(OracleParameterStatus.Success, d.Count()).ToArray();


        var arry3 = command.Parameters.Add("returnMessage", OracleDbType.Varchar2);
        //op = new OracleParameter("Accno", OracleDbType.Varchar2);
        arry3.Direction = ParameterDirection.Output;
        arry3.CollectionType = OracleCollectionType.PLSQLAssociativeArray;

        arry3.Size = d.Count();
        arry3.ArrayBindSize = c.Select(_ => _.ToString().Length).ToArray();
        arry3.ArrayBindStatus = Enumerable.Repeat(OracleParameterStatus.Success, d.Count()).ToArray();


        int r = command.ExecuteNonQuery();
        connection.Close();


        List<string> returnMessage = new List<string>();
                    returnMessage = ((command.Parameters[4].Value);                                    
        return returnMessage;


    }

现在我在第returnMessage = ((command.Parameters[4].Value);行

上收到错误

错误CS0266无法将类型'object'隐式转换为'System.Collections.Generic.List'。存在显式转换（您是否错过了演员？）

请帮我解决这个问题。

Answer 1

您的代码无法编译，因为command.Parameters[4].Value的编译时类型为object。

如果存储过程在输出参数中返回PL / SQL关联字符串数组，则ODP.NET将在存储过程调用完成后将参数值设置为C＃数组。然后，您需要获取该数组并将其转换为List<string>。

如果您使用的是Oracle托管数据访问（Oracle.ManagedDataAccess.dll），则该数组是C＃string的数组。要将其转换为List<string>，请使用：

    string[] returnMessage = (string[])(command.Parameters[4].Value);
    return returnMessage.ToList();

如果您使用的是非托管驱动程序（Oracle.DataAccess.dll），则该阵列将以OracleString的数组形式返回。从中获取这些字符串的工作可悲得多：

    OracleString[] returnMessage = (OracleString[])(command.Parameters[4].Value);
    List<string> strings = returnMessage.Select(os => os.IsNull ? null : os.Value).ToList();
    return strings

在C＃中检索PLSQLAssociativeArray的值

1 个答案: