MongoDB aggregate query with a where in node.js

Question

I have the following mongodb query in node.js which gives me a list of unique zip codes with a count of how many times the zip code appears in the database.

collection.aggregate( [
    {
        $group: {
            _id: "$Location.Zip",
            count: { $sum: 1 }
        }
    },
    { $sort: { _id: 1 } },
    { $match: { count: { $gt: 1 } } }
], function ( lookupErr, lookupData ) {
        if (lookupErr) {
            res.send(lookupErr);
            return;
        }
        res.send(lookupData.sort());
    });
});

How can this query be modified to return one specific zip code? I've tried the condition clause but have not been able to get it to work.

Verran · Accepted Answer · 2014-06-19 16:11:43Z

2

Aggregations that require filtered results can be done with the $match operator. Without tweaking what you already have, I would suggest just sticking in a $match for the zip code you want returned at the top of the aggregation list.

collection.aggregate( [
{   
    $match: {
        zip: 47421
    }
},
{
    $group: {
...

This example will result in every aggregation operation after the $match working on only the data set that is returned by the $match of the zip key to the value 47421.

answered Jun 19, 2014 at 16:11

Verran

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isaac9A · Accepted Answer · 2014-06-19 16:11:19Z

0

in the $match pipeline operator add

{ $match: { count: { $gt: 1 },
            _id : "10002" //replace 10002 with the zip code you want
}}

As a side note, you should put the $match operator first and in general as high in the aggregation chain as you can.

answered Jun 19, 2014 at 16:11

isaac9A

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Comments

mc100p · Accepted Answer · 2024-05-27 02:32:06Z

0

if your trying to do this for an object id and your not getting any results, try using the mongoose.Types.ObjectId(id)

for example:

   {
        $match: {
          userID: { $eq: new mongoose.Types.ObjectId(id) },
          searchIndex: { $ne: -1 },
        },
      },

answered May 27, 2024 at 2:32

mc100p

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