Using variables outside queries.

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1

Hello, I’m tring to use result variable outside quert results (to make a-b operation) but i cannot do it because variable is undefined. Can you help me please?

here the code:
export function calcolo()
{
let a;
let b;

  //Totali in lista 
  wixData.query("invitati_autorizzati") 
	.count() 
	.then( (results) => { 
                    a = results; 
} ); 

  //Totali iscritti 
  wixData.query("invitati_autorizzati") 
	.eq("iscritto", true) 
	.count() 
	.then( (results) => { 
            b=results; 
} );

console.log(a-b);
}

thanks
marco

2

Hi Marco,
Accessing data is an asynchronous operation, meaning you get the results at “a later time”.
That means that the order of execution of your code is something like:

  1. wixData.query(“invitati_autorizzati”).count()
  2. wixData.query(“invitati_autorizzati”).eq(“iscritto”, true).count()
  3. console.log(a-b)
  4. a = results;
  5. b=results;

Note that steps 4 and 5 can be switched, depending on the network status and how long the query runs on your database (5 can finish before 4), but the point here is that 4 and 5 will always happen after 3, because they are asynchronous.
What you need to do is “wait” for them to finish and only then print the result, something like this:

export function calcolo()
{
	//Totali in lista
	const firstPromise = wixData.query("invitati_autorizzati").count();

	//Totali iscritti
	const secondPromise = wixData.query("invitati_autorizzati")
		.eq("iscritto", true)
		.count();

	Promise.all([firstPromise, secondPromise])
		.then((a, b) => {
			console.log(a-b);
		});
}
3

Thanks a lot, it worked!
Marco