how to find by an array of ids en mongoose-CodePudding

this is my code:

const query = await Users.findOne({_id: userId}, 'groups');

const arrayOfGroups = [];

//query.groups is an array of strings that contains id´s
await Promise.all([query.groups.forEach(async function (groupId){
   const atributtesOfGroup = await Group.findById(groupId);
   const {grade, group, career} = atributtesOfGroup;
   arrayOfGroups.push(grade   '°'   group   '\n'   career);
})]);

i tried to find documents by an array (query.groups) of id´s and put those into the array "arrayOfGroups"

i also tried a query with $or but it didn´t work

some ideas? i just want an array with looks like this [grade '°' group '\n' career, grade '°' group '\n' career, grade '°' group '\n' career, ...]

CodePudding user response：

You don't have to call the async function inside a loop. You can simply use the $in operator to achieve the expected output.

    const user = await Users.findOne({_id: userId}, 'groups').lean()
    
    const allGroups = await Group.find({ _id: { $in: user.groups } }).lean()
    
    const arrayOfGroups = allGroups.map((group) => `${group.grade}°${group.group}'\n'${group.career}`)
    
    console.log(arrayOfGroups)

CodePudding user response：

A forEach does not return anything, you want to use the map-function. That returns an array of promises, so you don't need to add [...] as a parameter to your Promise.all.

You could also directly return text string in the inner function, no need to define arrayOfGroups upfront.