检索Linq到SQL中ID为动态的一行

Question

I have the following code:

var db = new IpsDBDataContext(connectionString);

var record = new IpsJobQueue();

var config = new IpsJobFileConfig();

record.FileName = file.Name;
record.FileNameConventionID = ....?
record.PickupDate = DateTime.Now;

// hard coded to follow suit with "unprocessed" flag in 
// IpsJobProcessCodes table.
record.ProcessStatus = 1; 
record.CreationTime = file.CreationTime;

record.StartTime = null;
record.EndTime = null;

db.IpsJobQueues.InsertOnSubmit(record);

db.SubmitChanges();

The line I am concerned with is record.FilenameConventionID =...?

Here, I need to assign the FileNameConventionID to a ID (as a foreign key) in the IpsJobFileConfig table where the PublisherName column = "Undetermined". Thats easy to do but the issue is the ID that is associated with this record type (Undetermined) will likely change as it gets promoted to production.

So what i perceive I need to do will be in two steps.

1. Find the record whose PublisherName = Undetermined
2. Get the ID on that record (as it will be dynamic).

The question is: How do I reflexively get the ID off the column whose record I am selecting?

Answer 1

Right now you're creating a new IpsJobFileConfig record but not using it. I'm guessing you could get rid of that altogether.

You should be able to get away with (assuming any record in the IpsJobFileConfig table with the correct publisher name will work since there could be multiple rows):

var config = db.IpsJobFileConfigs.First(c => c.PublisherName == "Undetermined");
record.FileNameConventionID = config.Id;

Answer 2

You have a JobQueue instance and a related previously existing JobFileConfig instance.

You should load the JobFileConfig from the database, like this:

JobFileConfig config = db.JobFileConfig.Where(c => c.PublisherName == "Undetermined").FirstOrDefault();

Then you should attach the new instance to the object graph like this:

config.JobQueues.Add(myJobQueue);

Don't assign the ID. Don't InsertOnSubmit the new JobQueue instance. It's connected to the object graph and the DataContext will manage the rest when you call SubmitChanges() . It will save the new instance to the database and populate any IDs back into your instance.

---

PS: DataContext implements IDispoable , so you should using it.

using(IpsDBDataContext db = new IpsDBDataContext(connectionString))
{
  ...
}