I've been having some difficulty working with fetching records from a form based on a lookup field value in that form.

This is for a simple inventory system app for tracking sticks of RAM in our inventory by the RAM Model and Quantity.  Types of RAM models are stored in their own "RAM_Models" form.  The "RAM_Inventory" form has a RAM Model lookup field which allows you to select any model from the RAM_Models form and also a Quantity field for tracking total quantity.  (There are other fields, such as Owner, which is also a lookup, but not directly relevant to this question).

What I am trying to do is fetch ALL records from RAM_Inventory that match the specific RAM_Model specified in the RAM_Model Lookup field in the RAM_Inventory form (so that I can then use a foreach to cycle through and total the quantity of that specific RAM model in RAM_Inventory).

The code looks like this:

2. // get RAM Model string
3. model = RAM_Models[ID = input.RAM_Model].Model;
4. 
   
5. // get totals for that model from Inventory and Project tables
6. modelRecords = RAM_Inventory[RAM_Model = model];
7. 
   
8. // add up quantities
9. totalInvQty = 0;
10. for each record in modelRecords {
11. totalInvQty = totalInvQty + record.Quantity;
12. }

Now, after much googling and painful trial and error I discovered that the input.RAM_Model lookup field doesn't return a string corresponding to the Model field in the RAM_Models form, but rather some kind of special lookup ID (which is why Line 2 queries the Model field directly to get the string rather than this long ID BIGINT).

This seems to make it impossible to fetch all records in RAM_Inventory with the model specified in the lookup input field.  Both of these return no records:

1. modelRecords = RAM_Inventory[RAM_Model = input.RAM_Model];

and attempting to get the RAM Model string and query this way doesn't work either:

1. model = RAM_Models[ID = input.RAM_Model].Model;
2. modelRecords = RAM_Inventory[RAM_Model = model];

Is there any way to get around this so that I can fetch all records in RAM_Inventory that have the same model as specified in RAM_Models in their associated lookup field?  Or is this simply not possible?