Error when accessing data within a query transformer

App Building
1

I'm trying to write a query transformer that relies on data from a previous query:

// type your code here
// example: return formatDataAsArray(data).filter(row => row.quantity > 20)

const programs_custom_question_ids =  {{  get_program.data.fields.custom_questions}}
//const programs_custom_question_ids  = ["rec7RuWdgx85aI5UU","recpT1GD6gnqsEu3A","recvy87rX2DovnorF"];
      
return data.records.filter(row => programs_custom_question_ids.includes(row.id)).map(row => row.fields)

The query that has this transformer is manually triggered on success when the preceding query (get_program) has completed. However since anything in {{}} is evaluated before the query / transformer runs, I get this error on page load:

Could not evaluate transformer in get_custom_questions_from_program: Error: Cannot read properties of null (reading 'records')

If I remove the {{}} and replace with a hardcoded array (see commented out line in transformer) there is no issue. I also tried adding some conditionals / optional chaining to no success.

Here are some related threads that describe this issue (without solutions):

What is the suggested approach here? Again, the transformer works as I need it to except for this erroneous error when Retool is attempting to evaluate the transformer before its needed. Thanks!

2

Hello! Retool team, any help here? This seems like fairly straightforward functionality...

3

Hi @r0meboards, Happy to help here! You could move this script to a Run JS code query that runs on success of the previous query. Alternatively, you add logic to this transformer to account for the case where {{ get_program.data }} is null. I hope that helps!

4

Thank you! For future reference, the error was being triggered not by the item in the scope (get_program.data) but rather the data variable in the transformer itself. This resolved the issiue:

const programs_custom_question_ids =  {{  get_program.data.fields.custom_questions }};
    
if(data !== null) {
    return data.records.filter(row => programs_custom_question_ids.includes(row.id)).map(row => row.fields)
} else {
    return [];
}