如何在猫鼬中查询对象数组内的值

Question

I'm trying to get document that it's 'from' field value in 'from' of 'periods' array.

I've tried followings but it doesn't work. how can i?

periods = [{
    from: 333,
    to: 555
},
{
    from: 666,
    to: 777
}]

var eqbookschema = new Schema({
eq_dbId: String,
user_dbId: String,
from: Number,
to: Number,
timestamp: Number,
}, {collection: 'book'});

EQBook = mongoose.model('EQBook', eqbookschema)

EQBook.find({
    eq_dbId: req.body.eq_dbId,
    from: {$in: [periods.from]}
})

The query I have tried only returns empty array although existing.

Answer 1

Because periods is an array of object and you want to find based on from field of each element so you need to map it first:

let froms = periods.map(val => val.from);

Then find with mapped array:

EQBook.find({
  eq_dbId: req.body.eq_dbId,
  from: {$in: froms}
})

Or just:

EQBook.find({
  eq_dbId: req.body.eq_dbId,
  from: {$in: periods.map(val => val.from)}
})

Answer 2

create an array of 'from' values only

periodFrom = periods.map((elem)=>elem.from);

EQBook.find(
  {eq_dbId: req.body.eq_dbId,from:{$in:periodFrom}}
)

Answer 3

You can try this.

const ObjectId = require('mongodb').ObjectId;
let froms = periods.map(data => data.from);
EQBook.aggregate([
{
 $match : {'eq_dbId': ObjectId(req.body.eq_dbId),'from':{$in:[periodFrom]}
}
])