MongoDB $project for field with spaces in the name

Question

I have a document that goes like this:

{
    "_id" : NumberLong(111603),
    "max" : "Created At",
    "document" : {
        "_id" : ObjectId("54ad61013e016de5798c0582"),
        "testfield1" : "ISUZU (GM)",
        "Model - Range" : "N-series",
        "testfield2" : "N NQR 75",
    }
}

And I would like to aggregate on the collection containing a number of these documents. I'm having an issue with the "Model - Range" in the $project step. Currently I am using

db.AE.aggregate([
    {"$project":{
        "Make":"$document.testfield1",
        "Model":"$document.testfield2",
        "_id":0, 
        "Group": "$document['Model - Range']"
     }}
]);

But for some reason, MongoDB is completely ignoring the Group field and only adding the other two fields.

Is there a way to address fields with spaces/special characters in them when projecting in MongoDB aggregation framework?

Yes it's not a valid way to notate this ( it is a string and not JavaScript code you did notice ) and you really should not name fields like this. Windows taught too many of the younger generation very bad habits. We code and model with consecutiveCamelCasedNames because we have experience and we know what works and what does not. — Neil Lunn
– Neil Lunn, Commented Jan 9, 2015 at 13:38
What if I have no control over the field names, based on the mongoDB documentation, the only characters that are not accepted are "." and ones that start with "$". — Bola
– Bola, Commented Jan 9, 2015 at 13:44
It got answered. I didn't want to because you really should not name properties this way. It only results in someone coming in and fixing your code. Leave a better legacy on the world and do it right the first time. — Neil Lunn
– Neil Lunn, Commented Jan 9, 2015 at 13:54
The fields get created by an external CSV file that I do not control. The entire idea of a noSQL database is that everything should be variable..types, names, etc.. I agree that naming conventions should exist even in noSQL but in this particular case the only way to do it is to re-adjust the field names while importing (again sort of defies the idea behind noSQL) — Bola
– Bola, Commented Jan 9, 2015 at 13:58
You know you can always "map" field names in CSV imports. So there is that. — Neil Lunn
– Neil Lunn, Commented Jan 9, 2015 at 14:00

JohnnyHK · Accepted Answer · 2015-01-09 13:51:30Z

7

You can just use normal dot notation for that field:

db.AE.aggregate([
    {"$project":{
        "Make":"$document.testfield1",
        "Model":"$document.testfield2",
        "_id":0, 
        "Group": "$document.Model - Range"
     }}
]);

But I agree with Neil that field names with spaces in them should be avoided, if possible.

answered Jan 9, 2015 at 13:51

JohnnyHK

313k70 gold badges632 silver badges479 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

MongoDB $project for field with spaces in the name

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related