node.js - expressJs - Wait for a promise inside a loop -


novice question; need create conditional loop makes call database. value returned promise determines if should break out of loop follows:

let id, caged;  {     caged = false;      id = models.cage.generateid();     caged = models.cage.findone({ where: { dispatchlabelid: id } });  } while( caged );

can please advise how can structure code?

you can using promises , recursive function calls:

let getcage = () => {   return models.cage     .generateid()     .then(id => models.cage.findone({ where: { dispatchlabelid: id } }))     .then(caged => {       if (caged) {         return caged;       }       return getcage();     }); }

in case if can use node.js v7.6 or higher can avoid using recursive function calls , implement using async/await:

let getcage = async () => {   try {     {       let id = await models.cage.generateid();       let caged = await models.cage.findone({ where: { dispatchlabelid: id } });       if (caged) {         return caged;       }     } while (true);   } catch (err) {     console.log(err);   } }

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