Returning a query result from a class's method

Question

I don’t know if this is possible, since i've do my best and still can’t resolve it here's my code

class account {
        constructor(id){
            this.id = id;
            this.solde = this.getSolde();
        }
     
        async getSolde(){
            const result = await con.query('SELECT solde FROM account WHERE id = ?', [this.id])
            return result[0];
        }
    }

When I call getSolde() I’ve either undefined or pending promise with different methods I've tried before, like getter, callback, none seems to work for me, can anyone help me

Thanks in advance

Duplicate of https://stackoverflow.com/questions/43431550/async-await-class-constructor/43433773 — Jagdish Idhate, Dec 31 '19 at 11:18

score 0 · Answer 1 · answered Dec 31 '19 at 11:15

0

getSolde() is async so you need to await it. But you can't do that inside the constructor because it needs to be marked as async, which can't be done.

Since you are returning the value, it should be returned if you just add a then on the promise:

constructor(id) {
    this.id = id;
    this.getSolde().then(result => this.solde = result);
}

answered Dec 31 '19 at 11:15

Shahzad

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i'm getting promise undefined – user9224596 Dec 31 '19 at 19:01
In `getSolde`, can you console.log(result) to confirm that you actually have a result which is an array and the result you want is at index 0. – Shahzad Dec 31 '19 at 19:05
in getSolde i'm getting Promise { } – user9224596 Jan 01 '20 at 20:17
now i managed to get result on console, with < const account = new acount(id); account.getSolde().then(result =>console.log(result)); but i can't assignt result to any variable, i can only console.log inside then method – user9224596 Jan 02 '20 at 23:05
@user9224596 you can do `account.getSolde().then(result => account.solde = result);` Or if you want to log out the result as well, you can put it inside a block: `account.getSolde().then(result => {console.log(result); result = account.solde;});` – Shahzad Jan 03 '20 at 11:29
how could I call account.solde if this isn't defined inside constructor ? – user9224596 Jan 03 '20 at 13:24
Maybe this will help you understand: `const a = new account(1); a.getSolde().then(result => a.solde = result).then(_ => console.log(a.solde));` – Shahzad Jan 03 '20 at 14:18

score 0 · Answer 2 · answered Dec 31 '19 at 11:20

0

It is recommended to avoid asynchronous actions inside your constructor. It would be better to instantiate the class with using id and then externally call getSolde():

const account = new account(id: 1);
await account.getSolde();

answered Dec 31 '19 at 11:20

Daniel Stoyanoff

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i thought it's not possible to wait outside an async function, anyway i've tried and isn't working – user9224596 Dec 31 '19 at 18:57
await account.getSolde() ^^^^^ SyntaxError: await is only valid in async function – user9224596 Jan 02 '20 at 23:02
Well, apparently you need to have an async function in order to await another function. If possible, please provide your source code, so we can guide you want to change. – Daniel Stoyanoff Jan 04 '20 at 00:03

Returning a query result from a class's method

2 Answers2