Nested queries in Mongo DB using mongoose and NodeJS

Question

I have this two Collections that I use, I need to query from one of the collection using params from the first collection

Collection expamples:

Collection 1 :{
id: 1234,
lastDate : "2020-09-10T08:30:14.960+00:00"
}

Collection 2 :{
site : 1234,
date : "2020-09-10T08:30:14.960+00:00"
}

I need to get the id and "lastDate" from Collection 1 and use it to query on Collection 2

sorry for bad explanation tell if need more info or anything

ADDED SQL equivalent

SELECT * FROM collection2 
WHERE site IN (SELECT id FROM collection1) and
 date IN (SELECT lastDate FROM collection1);

Kuldeep Mishra · Accepted Answer · 2020-10-06 12:00:20Z

1

 let params  = {_id:1}
 let data = await Collection1.aggregate([
    {$match:params},
   {
      $lookup: {
        from: "collection2",
        localField: "$collection1datefield",
        foreignField: "$collection2datefield",
        as: "collection2Object"
      }
   }
  ])

edited Oct 6, 2020 at 12:00

answered Oct 6, 2020 at 11:21

Kuldeep Mishra

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6 Comments

ShobiDobi Over a year ago

I have more then one in each collection... this is just an example for one document...

Kuldeep Mishra Over a year ago

your means from collection1 you will fetch multiple document then you will match with collection 2?

ShobiDobi Over a year ago

I will fetch multple document from both collections i need the data from collection two, collection one is the query param conditions

ShobiDobi Over a year ago

Sorry i think you didn't understand me ( its my bad not yours ) ill try to be more clear, I need to get All the ids and lastDate and compare them to the site and date on collection 2 i have this sql query that i think suppose to do the same in sql ( i know sql better then mongo so it is more easy from to demonstrate it like this): Added in orignal post

Kuldeep Mishra Over a year ago

try me code it will return all matched data from collection one. then i have done a lookup (Join) with 2nd collection with date. where date from first collection will match in 2nd collection that document you will from 2nd collection.

|

Hemant · Accepted Answer · 2020-10-06 11:29:35Z

0

If you have done referencing into the first collection then you can use simple query i.e

const query = await Collection1.findOne({id: req.params.id}).populate('site lastDate');

answered Oct 6, 2020 at 11:29

Hemant

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1 Comment

ShobiDobi Over a year ago

I need the Date from collection two to be the same as lastDate... and id need to be the same ofcurse. populate will return any popaple lastDate

Tahero · Accepted Answer · 2020-10-06 12:12:19Z

0

 db.FIRST_COLLECTION.aggregate([
  {
    $lookup: {
      from: "FIRST_COLLECTION",
      localField: "id", // local field of first collection
      foreignField: "site", // foreign field at second collection
      as: "liste",
    },
  },
  { $unwind: "$liste" },
  {
    $group: {
      _id: "$site",
      data: {
        $addToSet: {
          site: $site,
          date: $date,
        },
      },
    },
  },
]);

I invite you to read more about Aggregation

edited Oct 6, 2020 at 12:12

answered Oct 6, 2020 at 12:00

Tahero

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2 Comments

ShobiDobi Over a year ago

Already tried this... this will give the data from both collection i need only from collection2

Tahero Over a year ago

i have updated the query to group data using site so you will have just sites

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