我试图在EF中调用SQL SCALAR函数。我尝试了各种各样的例子，但我一直在努力：
y类型上指定的方法x无法转换为LINQ 到实体存储表达式。
我正在使用...
QUERY：
注意我在SELECT ...
public IQueryable<MeterDataItem> Query()
{
var query = from meter in UnitOfWork.Meter
join meterType in UnitOfWork.MeterType on meter.MeterTypeId equals meterType.Id into meterTypeLEFTJOIN
from meterType in meterTypeLEFTJOIN.DefaultIfEmpty()
join company in UnitOfWork.Company on meter.CompanyId equals company.Id
join meterPosition in UnitOfWork.EFMMeterPosition on meter.EFMMeterPositionId equals meterPosition.Id into meterPositionLEFTJOIN
from meterPosition in meterPositionLEFTJOIN.DefaultIfEmpty()
join flowType in UnitOfWork.FlowType on meter.FlowTypeId equals flowType.Id into flowTypeLEFTJOIN
from flowType in flowTypeLEFTJOIN.DefaultIfEmpty()
join fluidType in UnitOfWork.FluidType on meter.FluidTypeId equals fluidType.Id into fluidTypeLEFTJOIN
from fluidType in fluidTypeLEFTJOIN.DefaultIfEmpty()
join runStatus in UnitOfWork.RunStatus on meter.RunStatusId equals runStatus.Id into runStatusLEFTJOIN
from runStatus in runStatusLEFTJOIN.DefaultIfEmpty()
join pipeline in UnitOfWork.Pipeline on meter.PipelineId equals pipeline.Id into pipelineLEFTJOIN
from pipeline in pipelineLEFTJOIN.DefaultIfEmpty()
// Device portion
join device in UnitOfWork.Device on meter.DeviceId equals device.Id into deviceLEFTJOIN
from device in deviceLEFTJOIN.DefaultIfEmpty()
join rtuDevice in UnitOfWork.RTUDevice on device.Id equals rtuDevice.DeviceId into rtuDeviceLEFTJOIN
from rtuDevice in rtuDeviceLEFTJOIN.DefaultIfEmpty()
// Contact portion
join measureTech in UnitOfWork.User on rtuDevice.MeasurementTechnicianId equals measureTech.Id into measureTechLEFTJOIN
from measureTech in measureTechLEFTJOIN.DefaultIfEmpty()
join commTech in UnitOfWork.User on rtuDevice.CommunicationTechnicianId equals commTech.Id into commTechLEFTJOIN
from commTech in commTechLEFTJOIN.DefaultIfEmpty()
// Connection portion
join deviceCircuit in UnitOfWork.DeviceCircuit on device.Id equals deviceCircuit.DeviceId into deviceCircuitLEFTJOIN
from deviceCircuit in deviceCircuitLEFTJOIN.DefaultIfEmpty()
join circuit in UnitOfWork.Circuit on deviceCircuit.CircuitId equals circuit.Id
join circuitConnection in UnitOfWork.CircuitConnection on circuit.Id equals circuitConnection.CircuitId
join connection in UnitOfWork.Connection on circuitConnection.ConnectionId equals connection.Id
where
deviceCircuit.IsPrimary == true
select new MeterDataItem()
{
MeterId = meter.Id,
MeterNumber = meter.MeterNumber,
MeterName = meter.MeterName,
MeterTypeId = meterType.Id,
MeterTypeName = meterType.MeterTypeName,
MeterPositionCategory = meterPosition.EFMMeterPositionCategory,
FlowTypeName = flowType.FlowTypeName,
FluidTypeCategory = fluidType.FluidTypeCategory,
RunStatusCategory = runStatus.RunStatusCategory,
PipelineName = pipeline.PipelineName,
CompanyName = company.CompanyName,
ConnectionValue = GetConnection(circuitConnection.Id, connection.ConnectionTypeName),
DeviceId = device.Id,
DeviceName = device.DeviceName,
MeasurementTechnicianId = measureTech.Id,
MeasurementTechnicianFirstName = measureTech.FirstName,
MeasurementTechnicianLastName = measureTech.LastName,
CommunicationTechnicianId = commTech.Id,
CommunicationTechnicianFirstName = commTech.FirstName,
CommunicationTechnicianLastName = commTech.LastName,
MeterObjectStateName = null, //<-- Default Value
FavoriteId = 0 //<-- Default Value
};
return query.OrderBy(x => x.MeterNumber);
}
CSHARP-FUNCTION：
我猜它由于某种原因无法找到这个功能......
[Function(FunctionType.ComposableScalarValuedFunction, nameof(svfn_GetMeterConnection), Schema = "dbo")]
[return: Parameter(DbType = "VARCHAR(100)")]
public string svfn_GetMeterConnection([Parameter(DbType = "INT")]int circuitConnectionId, [Parameter(DbType = "VARCHAR(50)")]string connectionTypeName)
{
ObjectParameter circuitConnectionIdParameter = new ObjectParameter("@CircuitConnectionId", circuitConnectionId);
ObjectParameter connectionTypeNameParameter = new ObjectParameter("@ConnectionTypeName", connectionTypeName);
return UnitOfWork.DbContext.ObjectContext().ExecuteFunction<string>(nameof(this.svfn_GetMeterConnection), circuitConnectionIdParameter, connectionTypeNameParameter).SingleOrDefault();
}
SQL-FUNCTION：
我所有的名字和参数名称引用看起来正确...
ALTER FUNCTION [dbo].[svfn_GetMeterConnection]
(
@CircuitConnectionId INT,
@ConnectionTypeName VARCHAR(50)
)
RETURNS VARCHAR(100)
AS
BEGIN
DECLARE @Value VARCHAR(100) = NULL;
-- DIAL-UP
IF(@ConnectionTypeName = 'Dial-Up')
BEGIN
SELECT
@Value = circuitConnectionConfiguration.ConnectionPropertyValue
FROM [dbo].[CircuitConnectionConfiguration] circuitConnectionConfiguration
JOIN [dbo].[ConnectionConfiguration] connectionConfiguration ON connectionConfiguration.Id = circuitConnectionConfiguration.ConnectionConfigurationId
JOIN [dbo].[ConnectionProperty] connProperty ON connProperty.Id = connectionConfiguration.ConnectionPropertyId
WHERE
circuitConnectionConfiguration.CircuitConnectionId = @CircuitConnectionId
AND connProperty.ConnectionPropertyName = 'Dial-Up Number'
END
-- INTERNET PROTOCOL (IP)
IF(@ConnectionTypeName = 'Internet Protocol (IP)')
BEGIN
SELECT @Value =
((SELECT circuitConnectionConfiguration.ConnectionPropertyValue
FROM [dbo].[CircuitConnectionConfiguration] circuitConnectionConfiguration
JOIN [dbo].[ConnectionConfiguration] connectionConfiguration ON connectionConfiguration.Id = circuitConnectionConfiguration.ConnectionConfigurationId
JOIN [dbo].[ConnectionProperty] connProperty ON connProperty.Id = connectionConfiguration.ConnectionPropertyId
WHERE
circuitConnectionConfiguration.CircuitConnectionId = @CircuitConnectionId
AND connProperty.ConnectionPropertyName = 'IP Address')
+ ':' +
(SELECT circuitConnectionConfiguration.ConnectionPropertyValue
FROM [dbo].[CircuitConnectionConfiguration] circuitConnectionConfiguration
JOIN [dbo].[ConnectionConfiguration] connectionConfiguration ON connectionConfiguration.Id = circuitConnectionConfiguration.ConnectionConfigurationId
JOIN [dbo].[ConnectionProperty] connProperty ON connProperty.Id = connectionConfiguration.ConnectionPropertyId
WHERE
circuitConnectionConfiguration.CircuitConnectionId = @CircuitConnectionId
AND connProperty.ConnectionPropertyName = 'Port'))
END
-- Return the result of the function
RETURN @Value
END
更新 - 回答：
我需要的一些改变包括：
CONCRETE DBCONTEXT：
包括命名空间......
using EntityFramework.Functions;
using StructureMap;
using System.Configuration;
using System.Data.Entity;
using System.Data.Entity.Core.Objects;
using System.Linq;
public class MeasurementContractsDbContext : BaseDbContext
{
#region <Constructors>
[DefaultConstructor]
public MeasurementContractsDbContext() : base(Settings.ConnectionString.Database.MeasurementContractsDb)
{
Database.SetInitializer<MeasurementContractsDbContext>(null);
Database.CommandTimeout = int.Parse(ConfigurationManager.AppSettings[Settings.Command.TimeoutInterval]);
Configuration.ProxyCreationEnabled = false;
}
#endregion
#region <Methods>
[Function(FunctionType.ComposableScalarValuedFunction, nameof(svfn_GetMeterConnection), Schema = "dbo")]
[return: Parameter(DbType = "varchar")]
public string svfn_GetMeterConnection(int circuitConnectionId, string connectionTypeName)
{
ObjectParameter circuitConnectionIdParameter = new ObjectParameter("CircuitConnectionId", circuitConnectionId);
ObjectParameter connectionTypeNameParameter = new ObjectParameter("ConnectionTypeName", connectionTypeName);
return this.ObjectContext().ExecuteFunction<string>(nameof(this.svfn_GetMeterConnection), circuitConnectionIdParameter, connectionTypeNameParameter).SingleOrDefault();
}
[Function(FunctionType.ComposableScalarValuedFunction, nameof(svfn_GetCurrentObjectStateName), Schema = "dbo")]
[return: Parameter(DbType = "varchar")]
public string svfn_GetCurrentObjectStateName(int contextId, string contextFullName)
{
ObjectParameter contextIdParameter = new ObjectParameter("contextId", contextId);
ObjectParameter contextFullNameParameter = new ObjectParameter("contextFullName", contextFullName);
return this.ObjectContext().ExecuteFunction<string>(nameof(this.svfn_GetCurrentObjectStateName), contextIdParameter, contextFullNameParameter).SingleOrDefault();
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
// ADD Functions
modelBuilder.Conventions.Add(new FunctionConvention<MeasurementContractsDbContext>());
// ...
}
#endregion
}
示例使用：
/// <exception cref="ArgumentNullException">Non-Existent 'Query' value throws this exception</exception>
public IQueryable<MeterDetailDataItem> AuthorizationToFlowMeterDocumentFilter(IQueryable<MeterDetailDataItem> query)
{
if (query == null)
throw new ArgumentNullException("Query");
string contextFullName = typeof(AuthorizationToFlowMeterDocument).FullName;
// Get the ATF (if it exists)
var filteredQuery = (from dataitem in query //<-- QUERY
join document in UnitOfWork.Document on dataitem.RequestToFlowMeterDocumentId equals document.ParentId
// TODO: Figure out if you can move svfn_GetCurrentObjectStateName into an Algorythm class that can be injected
// SQL Function
let objectStateName = ((MeasurementContractsDbContext)UnitOfWork.DbContext).svfn_GetCurrentObjectStateName(document.Id, contextFullName)
select new MeterDetailDataItem()
{
MeterId = dataitem.MeterId,
RequestToFlowMeterDocumentId = dataitem.RequestToFlowMeterDocumentId,
RequestToFlowMeterDocumentObjectStateName = dataitem.RequestToFlowMeterDocumentObjectStateName,
AuthorizationToFlowMeterDocumentId = document.Id,
AuthorizationToFlowMeterDocumentObjectStateName = objectStateName,
FirstDeliveryNoticeDocumentId = dataitem.FirstDeliveryNoticeDocumentId,
FirstDeliveryNoticeDocumentObjectStateName = dataitem.FirstDeliveryNoticeDocumentObjectStateName,
FavoriteId = dataitem.FavoriteId
});
return filteredQuery.OrderBy(x => x.MeterId);
}
答案 0 :(得分：2)
看起来您正在使用EntityFramework.Functions包。然后看看Function主题。您正在使用标量值函数，不可组合，根据包作者
可以像其他上述方法一样直接调用
但
但是，由于它被指定为不可组合，因此LINQ to Entities查询中的实体框架无法将其翻译
和
这是按实体框架设计的
你需要的是标量值函数，可组合，其中
适用于LINQ to Entities查询，但无法直接调用
很快，由于您在LINQ to Entities查询中使用它，因此请在FunctionType.ComposableScalarValuedFunction注释中使用Function。因为它不是直接可调用的，所以它不需要方法体，所以你可以简单地抛出异常：
[Function(FunctionType.ComposableScalarValuedFunction, nameof(svfn_GetMeterConnection), Schema = "dbo")]
public string svfn_GetMeterConnection(int circuitConnectionId, string connectionTypeName)
{
throw new NotSupportedException();
}
并且不要忘记注册链接中显示的功能，否则它们将无效并且您将继续获得NotSupportedException：
modelBuilder.Conventions.Add(new FunctionConvention<TheClassContainingTheFunction>());