This is what I am trying to accomplish:

• Each user will receive a link to a published Nintex form.  The form acts as a purchase order.
• Each link will include a unique, obfuscated URL parameter, like:  "Code=AG13AS", which will be available to the form as a variable.
• Each code corresponds to several values stored in a separate data source (like a SharePoint list).  For example, the code might represent commercial terms that are unique to that user, which can be retrieved based on the code.  The data source has these columns:  Code, Price, NumberOfUsers, Duration.
• I want to show in the form that the user completes the terms from the data source, so the user knows what they are agreeing to purchase.  Each term would be stored as a variable with read-only access.  I also want those variables available for the entire workflow, such as to save elsewhere, include in a generated document, etc.

Is there a way to take a URL parameter for a form and perform a data lookup which then populates several other form variables?  I was hoping to use the Data Lookup feature, that but appears only to populate a choice field and there does not seem to be a way to limit what is returned based on a variable (like Code) in the form.

I could perform the lookup AFTER the form is submitted, but I need the lookup information to be shown in the form.