How to query with conditionals in MongoDB

Question

I am new to MongoDB and am learning how to query for multiple things at once with conditionals. I have a database with a document called 'towns' that contains an id, name, population, date of last census, items it is famous for, and mayor. For example, this is what one of the towns looks like (please keep in mind, this is old, random data, nothing is up to date, it is just an example for me to learn):

{
        "_id" : ObjectId("60232b0bbae1e5336c5ebc96"),
        "name" : "New York",
        "population" : 22200000,
        "lastCensus" : ISODate("2016-07-05T00:00:00Z"),
        "famousFor" : [
                "the MOMA",
                "food"

        ],
        "mayor" : {
                "name" : "Bill de Blasio",
                "party" : "D"
        }

I am trying to find all towns with names that contain an e and that are famous for food or beer. I currently have this query:

db.towns.find({name: {$regex:"e"}}, {$or: [{famousFor:{$regex: 'food'}}, {famousFor:{$regex: 'beer'}}]})

If I split up the name and the $or expression, it works, but together I get errors like:

Error: error: {
        "ok" : 0,
        "errmsg" : "Unrecognized expression '$regex'",
        "code" : 168,
        "codeName" : "InvalidPipelineOperator"

Or, if I switch the query to db.towns.find({name:/e/}, {$or: [{famousFor:/food/}, {famousFor:/beer/}]}) I get the error:

Error: error: {
        "ok" : 0,
        "errmsg" : "FieldPath field names may not start with '$'.",
        "code" : 16410,
        "codeName" : "Location16410"

What am I doing wrong? Is it how I am structuring the query?

Thanks in advance!

Gibbs · Accepted Answer · 2021-02-10 03:19:59Z

1

Problem Is the syntax.

find({condition goes here}, {projection goes here})

You need to put all of your conditions within one curly brace.

db.towns.find({name: {$regex:"e"}, $or: [{famousFor:{$regex: 'food'}}, {famousFor:{$regex: 'beer'}}]})

answered Feb 10, 2021 at 3:19

Gibbs

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1 Comment

Samantha Over a year ago

Ahh! Thank you so much!

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