How to return newly saved record id from wcf service asynchronously

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Hi,

I have a regular requirement for returning newly saved record id from database through wcf service.

I have a service which is used to save the record and at the same time the newly inserted record id (say ConsultationID) need to return from the service.

But unfortunately, the asynchronous service initially returns 0, which is the initial value and after the method executes, it returns the actual value. Can anybody tell me how to retrieve the return value from the service synchronoysly.

Code Sample:

public int SaveConsultation()
{
   ConsultationService client=new ConsultationService();

   ConsultationService.Consultation objConsultaiton =      
        ConsultationService.Consultation();

   objConsultaiton.consultaitonName = "xxxxx";

   objConsultaiton.consultaitonAddress = "yyyyyyy";

   client.saveRecordAsync(objConsultaiton);

   client.saveRecordCompleted += (ss,ee)=> {
       objConsultaiton.consultationID = ss.result;
   };

   return objConsultaiton.consultationID;

}

But " return objConsultaiton.consultationID " is executed before client.saveRecordCompleted event and i am getting the cnsultationID as '0'

Please suggest me the solution.

Posted 2-Dec-09 2:43am

Veerendranadh

Updated 2-Dec-09 3:54am

Chris Maunder772.9K

v2

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raelango · Answer 1 · 2009-12-02T22:23:00

There are 2 errors that I could see:

1. The call to method client.saveRecordAsync(objConsultaiton) should be called *after* attaching the client.saveRecordCompleted event handler.
2. Since the consultationID is available only after the Asynchronous call is returned, you need to wait for the Asynchronous call to complete.

The following changed code should work (I have not tested the code):

public int SaveConsultation() 
{   
ConsultationService client=new ConsultationService();   ConsultationService.Consultation objConsultaiton =             ConsultationService.Consultation();   
objConsultaiton.consultaitonName = "xxxxx";   objConsultaiton.consultaitonAddress = "yyyyyyy";  
AutoResetEvent objAutoReset = new AutoResetEvent(false); //flag to track call back
client.saveRecordCompleted += (ss,ee)=> 
{       
    objConsultaiton.consultationID = ss.result;   
    objAutoReset.Set();  //flag confirming call back
};   
client.saveRecordAsync(objConsultaiton);   
objAutoReset.WaitOne(); //Wait till the flag is set by Async Call back
return objConsultaiton.consultationID;
}