Entity Framework 6, Command Interception & Stored Procedures

I was asked to develop auditing for a system at my work. The system has already been completed. I think EF 6's Command Interception should work well for my purposes.

However, there are situations like this where we would want to know who sent a request for leave, and we would like to be able to intercept this Insert query.

using (DataContext context = new DataContext())
    {
      var result = context.CreateLeavePrerequest(
        leaveRequest.LeaveType,
        leaveRequest.StartDate,
        leaveRequest.EndDate,
        leaveRequest.NumberOfDays,
        leaveRequest.EmployeeComment,
        leaveRequest.HasSupportingDocumentation,
        leaveRequest.ResourceTag,
        leaveRequest.RemainingBalance,
        leaveRequest.ApproverResourceTag,
        leaveRequest.CapturerResourceTag,
        leaveRequest.SupportingDocumentID,
        ref id
        );

then the stored procedure is:

CREATE PROCEDURE [dbo].[CreateLeavePrerequest]
(
  @LeaveType VARCHAR(50) ,
  @StartDate DATETIME ,
  @EndDate DATETIME ,
  @NumberOfDays DECIMAL(18, 5) ,
  @EmployeeComment VARCHAR(512) ,
  @SickNoteIndicator BIT ,
  @ResourceTag INT,
  @RemainingBalance DECIMAL,
  @ApproverResourceTag INT,
  @CapturerResourceTag INT,
  @SupportingDocumentID INT,
  @id INT = 0 OUT
)  
AS 
BEGIN
    INSERT  INTO [ESS PER LVE PreRequest]
            ( [Resource Tag] ,
              [Leave Type] ,
              [Start Date] ,
              [End Date] ,
              [No Of Days] ,
              [Employee Comments] ,
              [Sick Note Indicator],
              [Status],
              [Remaining Balance],
              [Approver Resource Tag],
              [Capturer Resource Tag],
              [SupportingDocumentID]
            )
            SELECT  @ResourceTag ,
                    @LeaveType ,
                    @StartDate ,
                    @EndDate ,
                    @NumberOfDays ,
                    @EmployeeComment ,
                    @SickNoteIndicator,
                    'Captured',
                    @RemainingBalance,
                    @ApproverResourceTag,
                    @CapturerResourceTag,
                    @SupportingDocumentID;
SELECT @id
END 

UPDATE:

CreateLeavePrerequest is implemented as follows:

public ISingleResult<CreateLeavePrerequestResult> CreateLeavePrerequest([global::System.Data.Linq.Mapping.ParameterAttribute(Name="LeaveType", DbType="VarChar(50)")] string leaveType, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="StartDate", DbType="DateTime")] System.Nullable<System.DateTime> startDate, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="EndDate", DbType="DateTime")] System.Nullable<System.DateTime> endDate, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="NumberOfDays", DbType="Decimal(18,5)")] System.Nullable<decimal> numberOfDays, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="EmployeeComment", DbType="VarChar(512)")] string employeeComment, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="SickNoteIndicator", DbType="Bit")] System.Nullable<bool> sickNoteIndicator, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="ResourceTag", DbType="Int")] System.Nullable<int> resourceTag, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="RemainingBalance", DbType="Decimal(18,0)")] System.Nullable<decimal> remainingBalance, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="ApproverResourceTag", DbType="Int")] System.Nullable<int> approverResourceTag, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="CapturerResourceTag", DbType="Int")] System.Nullable<int> capturerResourceTag, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="SupportingDocumentID", DbType="Int")] System.Nullable<int> supportingDocumentID, [global::System.Data.Linq.Mapping.ParameterAttribute(DbType="Int")] ref System.Nullable<int> id)
    {
        IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), leaveType, startDate, endDate, numberOfDays, employeeComment, sickNoteIndicator, resourceTag, remainingBalance, approverResourceTag, capturerResourceTag, supportingDocumentID, id);
        id = ((System.Nullable<int>)(result.GetParameterValue(11)));
        return ((ISingleResult<CreateLeavePrerequestResult>)(result.ReturnValue));
    }

UPDATE 2

DBCommandInterceptor registration in Global.asax:

 protected void Application_Start()
 {
     DbInterception.Add(new Auditor());
 }

DBCommandInterceptor implementation:

I implemented this quickly so that I could just see whether I could intercept anything, so it just writes to the Debug window. I have been able to intercept some Select queries, but that's not what we want to audit.

 public class Auditor : IDbCommandInterceptor
{
    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        CreateAuditMessage(command, interceptionContext);
    }
public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext&lt;int&gt; interceptionContext)
{
    CreateAuditMessage(command, interceptionContext);
}

public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext&lt;DbDataReader&gt; interceptionContext)
{
    CreateAuditMessage(command, interceptionContext);
}

public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext&lt;DbDataReader&gt; interceptionContext)
{
    CreateAuditMessage(command, interceptionContext);
}

public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext&lt;object&gt; interceptionContext)
{
    CreateAuditMessage(command, interceptionContext);
}

public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext&lt;object&gt; interceptionContext)
{
    CreateAuditMessage(command, interceptionContext);
}

public static void CreateAuditMessage&lt;T&gt;(DbCommand command, DbCommandInterceptionContext&lt;T&gt; interceptionContext)
{
    string message;

    var parameters = new StringBuilder();
    foreach (DbParameter param in command.Parameters)
    {
        parameters.AppendLine(param.ParameterName + " " + param.DbType + " = " + param.Value);
    }

    if (interceptionContext.Exception == null)
    {
        message = (parameters.ToString() + "  " + command.CommandText);
    }
    else
    {
        message =  (parameters.ToString() + command.CommandText + "  " + interceptionContext.Exception);
    }

    Debug.WriteLine(message);
}

}

Recently, I’ve been reading a lot about Entity Framework, but I am not very knowledgeable. I have implemented the IDbCommandInterface and registered it etc. I am able to see some other queries being intercepted, but since the above situation is such that the stored procedure is being called “outside” I can’t get hold of the parameters.

This is a simple example. Not all the stored procedures that are called in a similar way in the system are so simple.

What would be the best way to change the above situation so that we can apply the interception and thus the auditing?

#c-sharp #sql #sql-server #entity-framework