Cannot group with more than one field name

[prusfr]

Pipeline.group() method wont' allow more than 1 field name of class string, whereas doc indicates set or list can be passed.
Example :
Pipeline().group(by=["field1", "field2"]) will throw an error.
Thus, multi-fields group cannot be set and such a syntax : {$group: {$_id : { field1: "$field1", field2: "$field2"}}} cannot be achived

[VianneyMI]

Thanks for the report.

Yes the doc is a bit misleading. I am currently working on creating a proper documentation for the package.
I'll fix this soon.

In the meantime you can still write:

Pipeline().group(    
        query = {
            "field1":"$field1",
            "field2":"$field2",
        }
    )

[VianneyMI]

Fixed in 0.16.2