使用带有输出参数的实体框架调用 Oracle 存储过程？

Question

我有一个简单的 Oracle 存储过程，它传入三个参数，并有一个输出参数：

CREATE OR REPLACE PROCEDURE RA.RA_REGISTERASSET
(
    INPROJECTNAME IN VARCHAR2
    ,INCOUNTRYCODE IN VARCHAR2
    ,INLOCATION IN VARCHAR2
    ,OUTASSETREGISTERED OUT VARCHAR2
)
AS
BEGIN
  SELECT 
      INPROJECTNAME || ', ' || INLOCATION || ', ' || INCOUNTRYCODE
  INTO
      OUTASSETREGISTERED
  FROM
      DUAL;     
END RA_REGISTERASSET;

我正在尝试使用 Entity Framework 6.1 来取回 OutAssetRegistered 值，但是，在调用 SqlQuery 后我得到一个空值，无一例外：

public class CmdRegisterAssetDto
{
        public string inProjectName { get; set; }
        public string inCountryCode { get; set; }
        public string inLocation { get; set; }
        public string OutAssetRegistered { get; set; }
}

//--------------------------------------------- ---------------

string projectName = "EXCO";
string location = "ANYWHERE";
string countryCode = "XX";

using (var ctx = new RAContext())
{
    var projectNameParam = new OracleParameter("inProjectName", OracleDbType.Varchar2, projectName, ParameterDirection.Input);
    var countryCodeParam = new OracleParameter("inCountryCode", OracleDbType.Varchar2, countryCode, ParameterDirection.Input);
    var locationParam = new OracleParameter("inLocation", OracleDbType.Varchar2, location, ParameterDirection.Input);
    var assetRegisteredParam = new OracleParameter("OutAssetRegistered", OracleDbType.Varchar2, ParameterDirection.Output);

    var sql = "BEGIN RA.RA_RegisterAsset(:inProjectName, :inCountryCode, :inLocation, :OutAssetRegistered); END;";
    var query = ctx.Database.SqlQuery<CmdRegisterAssetDto>(sql, projectNameParam, countryCodeParam, locationParam, assetRegisteredParam
    );

    assetRegistered = (string)assetRegisteredParam.Value;
}

我一直在努力让这个工作无济于事，检查了不同的博客，所有其他的 crud 操作都有效，谁能帮助并指导我哪里出错了？

Answer 1

在这种情况下，你不应该打电话：

var query = ctx.Database.SqlQuery<CmdRegisterAssetDto>(sql, projectNameParam, countryCodeParam, locationParam, assetRegisteredParam);

而是调用：

var result = ctx.Database.ExecuteSqlCommand(sql, projectNameParam, countryCodeParam, locationParam, assetRegisteredParam);

请注意，唯一有效的区别是 SqlQuery<CmdRegisterAssetDto> 被替换为 ExecuteSqlCommand。这也意味着 DTO 是不必要的。否则，您的代码看起来应该可以工作。这是您的完整原始代码以及我提到的更改：

string projectName = "EXCO";
string location = "ANYWHERE";
string countryCode = "XX";

using (var ctx = new RAContext())
{
    var projectNameParam = new OracleParameter("inProjectName", OracleDbType.Varchar2, projectName, ParameterDirection.Input);
    var countryCodeParam = new OracleParameter("inCountryCode", OracleDbType.Varchar2, countryCode, ParameterDirection.Input);
    var locationParam = new OracleParameter("inLocation", OracleDbType.Varchar2, location, ParameterDirection.Input);
    var assetRegisteredParam = new OracleParameter("OutAssetRegistered", OracleDbType.Varchar2, ParameterDirection.Output);

    var sql = "BEGIN RA.RA_RegisterAsset(:inProjectName, :inCountryCode, :inLocation, :OutAssetRegistered); END;";
    var result = ctx.Database.ExecuteSqlCommand(sql, projectNameParam, countryCodeParam, locationParam, assetRegisteredParam);

    assetRegistered = (string)assetRegisteredParam.Value;
}

为了证明我的理论，我复制了您遇到的空行为，然后进行了一次更改。它挂了一会儿（可能是为了让 EF 启动），但此后每次都快速执行。在每种情况下，我都在 out 参数中找到了一个等待值。

如果有人遇到了麻烦，有一个简单的变体可以为您处理脚本细节：

string projectName = "EXCO";
string location = "ANYWHERE";
string countryCode = "XX";

using (var ctx = new RAContext())
using (var cmd = ctx.Database.Connection.CreateCommand())
{
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.CommandText = "RA.RA_REGISTERASSET";

    var projectNameParam = new OracleParameter("inProjectName", OracleDbType.Varchar2, projectName, ParameterDirection.Input);
    var countryCodeParam = new OracleParameter("inCountryCode", OracleDbType.Varchar2, countryCode, ParameterDirection.Input);
    var locationParam = new OracleParameter("inLocation", OracleDbType.Varchar2, location, ParameterDirection.Input);
    var assetRegisteredParam = new OracleParameter("OutAssetRegistered", OracleDbType.Varchar2, ParameterDirection.Output);
    cmd.Parameters.AddRange(new[] { projectNameParam, countryCodeParam, locationParam, assetRegisteredParam });

    cmd.Connection.Open();
    var result = cmd.ExecuteNonQuery();
    cmd.Connection.Close();

    assetRegistered = (string)assetRegisteredParam.Value;
}

作为事后的想法，如果您在之后立即调用查询（即query.FirstOrDefault()），从技术上讲，您可以使用原始解决方案。查询的返回值将始终为 null，但您的 out 参数至少会被填充。这是因为 EF 查询使用延迟执行。

Answer 2

如果您需要传入和/或传出日期：

        public DateTime GetDate(string dateIn)
        {
            Regex regex = new Regex(@"(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z)");

            if (!regex.IsMatch(dateIn))
            {
                throw new ArgumentException($"dateIn must be given in the YYYY-MM-DD\"T\"hh24:mi:ss\"Z\" format. " +
                    $"Value given: {dateIn}");
            }

            OracleParameter dateInParam = new OracleParameter("DATE_IN_", dateIn);
            createdParam.OracleDbType = OracleDbType.TimeStampTZ;
            OracleParameter dateOutParam= new OracleParameter("DATE_OUT_", OracleDbType.Date, System.Data.ParameterDirection.Output);

            var sql = "BEGIN " +
                $"Get_Date(:DATE_IN_, TO_TIMESTAMP_TZ('{dateIn}','YYYY-MM-DD\"T\"hh24:mi:ss\"Z\"'), :DATE_OUT_ ); " +
                "END;";

#pragma warning disable EF1000 // Possible SQL injection vulnerability.
            context.Database.ExecuteSqlCommand(sql, dateInParam, dateOutParam);
#pragma warning restore EF1000 // Possible SQL injection vulnerability.

            return (DateTime)(OracleDate)dateOutParam.Value;
        }