Using while loop in Promise()

Question

I have a user list and i am checking all user with certain details.I am using sequelize js with express.I want to know that can we use while loop like this for searching and saving data in database.Please help me.Thanks In advance.

let royalty_bonus = async (sponsor) => {
    return await new Promise((resolve, reject) => {
        models.RoyaltyUser.findById(sponsor)
            .then(async (sponsorRow) => {
                let user_level = 1;
                let sponsor_id = sponsorRow;

                try {
                    while (sponsor_id != null && user_level <= 3) {
                        let level_length = await getLevel(sponsor_id.id, user_level);
                        if (user_level === 1 && level_length.length === 3) {
                            console.log('Level One Achieved By ', sponsor_id.id);
                        } else if (user_level === 2 && level_length.length === 9) {
                            console.log('Level Two Is Achieved By ', sponsor_id.id);
                        } else {
                            console.log('No Level');
                        }

                        await models.RoyaltyUser.findOne({where: {id: sponsor_id.sId}})
                            .then((sponsor_new_row) => {
                                sponsor_id = sponsor_new_row;
                            })
                            .catch((e) => {
                                console.log(' Inner Catch Error ', e.message);
                                reject();
                            });
                        user_level++;
                    }
                    resolve();
                }
                catch (e) {
                    reject(e);
                }

            })
            .catch((e) => {
                reject('catch ', e.message);
            });
    });

};
router.get('/royalty_user', async (req, res, next) => {
    royalty_bonus(4)
        .then(() => {
            console.log('done');
        })
        .catch((e) => {
            console.log('Catch two', e.message);
        })
});

Avoid the [`Promise` constructor antipattern](https://stackoverflow.com/q/23803743/1048572?What-is-the-promise-construction-antipattern-and-how-to-avoid-it)! And avoid using `then` when you have `async`/`await`! — Bergi, Sep 08 '18 at 08:22
this is working as expected.But i am not sure that this will not fail at certain point.i am new to express.I just want to know that this kind of promise execution is right or wrong. — deep mann, Sep 08 '18 at 08:33
The `while` loop you asked about in the question title is fine, the rest is awful :-) — Bergi, Sep 08 '18 at 08:34
can u tell me how can i remove awful things?? bcz this is out of my scope — deep mann, Sep 08 '18 at 08:45

score 1 · Accepted Answer · answered Sep 08 '18 at 09:32

Avoid the Promise constructor antipattern, avoid return await, and don't mix .then callbacks with async/await syntax. You can simplify a lot:

async function royalty_bonus(sponsor) {
    const sponsorRow = await models.RoyaltyUser.findById(sponsor);
    let user_level = 1;
    let sponsor_id = sponsorRow;

    while (sponsor_id != null && user_level <= 3) {
        let level_length = await getLevel(sponsor_id.id, user_level);
        if (user_level === 1 && level_length.length === 3) {
            console.log('Level One Achieved By ', sponsor_id.id);
        } else if (user_level === 2 && level_length.length === 9) {
            console.log('Level Two Is Achieved By ', sponsor_id.id);
        } else {
            console.log('No Level');
        }

        const sponsor_new_row = await models.RoyaltyUser.findOne({where: {id: sponsor_id.sId}});
        sponsor_id = sponsor_new_row;
        user_level++;
    }    
}

router.get('/royalty_user', (req, res, next) => {
    royalty_bonus(4).then(() => {
        console.log('done');
    }, e => {
        console.log('Catch two', e.message);
    });
});

Using while loop in Promise()

1 Answers1