Can I clone an IQueryable in linq? For UNION purposes?

Question

I have a table of WorkOrders. The table has a PrimaryWorker & PrimaryPay field. It also has a SecondaryWorker & SecondaryPay field (which can be null).

I wish to run 2 very similar queries & union them so that it will return a Worker Field & Pay field. So if a single WorkOrder record had both the PrimaryWorker and SecondaryWorker field populated I would get 2 records back.

The "where clause" part of these 2 queries is very similar and long to construct. Here's a dummy example

var q = ctx.WorkOrder.Where(w => w.WorkDate >= StartDt && w.WorkDate <= EndDt);

if(showApprovedOnly)
{
   q = q.Where(w => w.IsApproved);
}
//...more filters applied

Now I also have a search flag called hideZeroPay. If that's true I don't want to include the record if the worker was payed $0. But obviously for 1 query I need to compare the PrimaryPay field and in the other I need to compare the SecondaryPay field.

So I'm wondering how to do this.

Can I clone my base query q and make a primary & secondary worker query out of it and then union those 2 queries together?

Answer 1

Hmm, I'm not sure that I understand you intention. But I think cloning is not neccessary. Why don't you split two new queries from your base query?

var baseQuery = ctx.WorkOrder.Where(w => w.WorkDate >= StartDt && w.WorkDate <= EndDt);

IQueryable<WorkOrder> query1;
if (showApprovedOnly)
{
  query1 = baseQuery.Where(w => w.IsApproved);
}
//more filters on query1
...

IQueryable<WorkOrder> query2;
if (/*something*/)
  query2 = baseQuery.Where(w => w.SomeThing);

After defining your queries you can interpret them (per enumeration) and retrieve your different results.

var res1 = query1.ToList();
var res2 = query2.ToList();

Answer 2

When you do your second Where you are actually cloning your query.

Here you create your initial queryable object.

var q = ctx.WorkOrder.Where(w => w.WorkDate >= StartDt && w.WorkDate <= EndDt);

Here you create a new queryable with the where associated

if(showApprovedOnly)
{
   q = q.Where(w => w.IsApproved);
}
//...more filters applied

All you need to do is create a new variable to store the ammended query.

var qw = q.Where(w=> w.IsApproved);

This works because the queryable is created as an object and the query itself is only run once you enumerate it.