Searching for a specific value within a hash in MongoDB

Question

Searching for a specific value within a hash in MongoDB

I am working with MongoDB documents formatted like this:

    {
      "_id": ObjectId("5406e4c49b324869198b456a"),
      "phones": {
        "12035508684": 1,
        "13399874497": 0,
        "15148399728": 1,
        "18721839971": 1,
        "98311321109": -1,
      }
    }

The phones field consists of a hash of phone numbers and their frequency of use.

I am trying to select all documents that have at least one phone number with a frequency of zero or less.

I attempted the following query:

    db.my_collection.find({"phones": { $lte: 0} })

Unfortunately, this query did not return the desired results.

Thank you in advance for any advice you can provide.

javascript mongodb mongodb-query

Answer 1

Answer №1

In MongoDB, performing a query like the one you are trying to do may not be straightforward. It is considered an "anti-pattern" to specify part of your data as "keys" in MongoDB. A better approach would be to model your data in a way where the "data" is a value to a key, instead of the other way around:

    {
      "_id": ObjectId("5406e4c49b324869198b456a"),
      "phones": [
        { "number": "12035508684", "value": 1 },
        { "number": "13399874497", "value": 0 },
        { "number": "15148399728", "value": 1 },
        { "number": "18721839971", "value": 1 },
        { "number": "98311321109", "value": -1 },
      }
    }

With this model, your query becomes simpler:

db.collection.find({ "phones.value": { "$lte": 0 } })

Trying to traverse the "keys" of an object/hash in MongoDB natively is not supported. You would need to use JavaScript evaluation for this, which can impact performance. An alternative would be using a $where query, like this:

db.collection.find(function() { 
    var phones = this.phones; 
    return Object.keys(phones).some(function(phone) { 
        return phones[phone] <= 0;
    }) 
})

It is recommended to reconsider the way you model your data in MongoDB and leverage the native operators for better query performance. Most queries in MongoDB require an explicit path to access any "key" inside an object/hash.

Answer 2

In MongoDB, performing a query like the one you are trying to do may not be straightforward. It is considered an "anti-pattern" to specify part of your data as "keys" in MongoDB. A better approach would be to model your data in a way where the "data" is a value to a key, instead of the other way around:

    {
      "_id": ObjectId("5406e4c49b324869198b456a"),
      "phones": [
        { "number": "12035508684", "value": 1 },
        { "number": "13399874497", "value": 0 },
        { "number": "15148399728", "value": 1 },
        { "number": "18721839971", "value": 1 },
        { "number": "98311321109", "value": -1 },
      }
    }

With this model, your query becomes simpler:

db.collection.find({ "phones.value": { "$lte": 0 } })

Trying to traverse the "keys" of an object/hash in MongoDB natively is not supported. You would need to use JavaScript evaluation for this, which can impact performance. An alternative would be using a $where query, like this:

db.collection.find(function() { 
    var phones = this.phones; 
    return Object.keys(phones).some(function(phone) { 
        return phones[phone] <= 0;
    }) 
})

It is recommended to reconsider the way you model your data in MongoDB and leverage the native operators for better query performance. Most queries in MongoDB require an explicit path to access any "key" inside an object/hash.

Searching for a specific value within a hash in MongoDB

Answer №1

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