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存储过程获取传入三个参数，并且有一个输出参数：

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; 

我试图使用实体框架6.1找回OutAssetRegistered值，但是，我得到一个空拨打SqlQuery后无一例外：

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; 
} 

我一直在努力争取这个工作无济于事，检查了不同的博客，所有其他crud操作工作，任何人都可以请协助，并指示我哪里出错了？

Answer 1

在这种情况下，你不应该叫：

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

而是应该呼吁：

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

注意，唯一有效的区别是SqlQuery<CmdRegisterAssetDto>与ExecuteSqlCommand取代。这也意味着DTO是不必要的。否则，你的代码看起来应该起作用。这是你的原代码，将其全部与我提到的更改：

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，我转载你所遇到的无效行为，然后做出一个改变。它挂了一下（可能让EF启动），但之后每次都快速执行。在每种情况下，我都在out参数中找到了一个值。

如果有人在那里运行陷入困境，有一个手写的变化是需要照顾的脚本细节为您提供：

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; 
} 

在事后，你在技术上可以与你原来的解决方案去，如果你调用查询后立即（即query.FirstOrDefault()）。查询的返回值将始终为空，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。