使用带有输出参数的Entity Framework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;

我试图使用Entity Framework 6.1来获取OutAssetRegistered值,但是,我在调用之后得到一个null SqlQuery,没有异常:

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操作工作,任何人都可以协助并指导我在哪里出错？

Answer 1

在这种情况下，您不应该调用：

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

但改为调用：

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，我重现了您正在经历的空行为，然后进行了这一更改。它挂起了一段时间（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 参数中找到了等待的值。

如果有人遇到麻烦，有一个普通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 ），那么从技术上讲，您可以采用原始解决方案query.FirstOrDefault()。查询的返回值始终为空，但您的输出参数至少会被填充。这是因为 EF 查询使用延迟执行。