CODEWITHSUNDEEP
mongodb
disruptive
disruptive

Reputation: 5946

Aggregate Conversion String to Int to with Mongo 3.2.9

The issue I have is making a conversion from a string to an integer in order to create an average. I know to use the $convert in later versions, but I cannot find the correct place to use the $toInt term. I know the conversion using this keyword works on the command line on a single example, but where should I place this within the aggregate framework.

db.my_batch.aggregate([
{ "$unwind": "$current.Data.x" },
{ "$match": { "current.Data.x.Typ": "01", "current.Data.x.Value": { "$lt": "TTTT" } } },
{ "$project": { "current.Data.x.Value": 1, "uId": 1 } },
{ "$group": { "_id": null, "ad": { "$avg": { "$toInt": "$current.Data.x.Value" } } } }]
)

I get the following response:

2018-07-20T17:19:42.707+0200 E QUERY    [thread1] Error: command failed: {
    "ok" : 0,
    "errmsg" : "Unrecognized expression '$toInt'",
    "code" : 168,
    "codeName" : "InvalidPipelineOperator"
} : aggregate failed :

Upvotes: 14

Views: 6715

Answers (2)

Nate Anderson
Nate Anderson

Reputation: 21044

I wanted to convert int to string (the opposite of OP's question).

I'm posting this answer here in case it helps someone. OP wanted $toInt, but I needed the opposite; $toString and/or $convert, but those are too new (MongoDB 4.0)

You can use $substr as seen here:

...
{ stringifiedInt: { $substr: ['$intProperty', 0, -1] } }
...

If you are looking to convert int to text, consider other options here which is very similar - Use Javascript on query results to .forEach and/or .map your results (but then you can't do aggregations)

You could:

Upvotes: 0

Paulius Venclovas
Paulius Venclovas

Reputation: 1598

Because $toInt and $convert operators were only added in mongodb 4.0, it is best for you to change field type in database and query after that.

Upvotes: 6

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