Mongoengine filtering on a listField with __contains not working

Question

I have a field in my document place_names which is a list of all possible place names for a location. Example New York City with have New York City, NYC, big apple etc. I want the user to be able to query on any of these values or any part of the above values. For example if they search for "apple" i want them to get New York City back. I was trying to use the __contains filter in mongoengine as below

place_names is of type ListField()

pn = request.POST.get('place_name', None)

try:
    places_list = Places.objects()
    if pn is not None and pn != "":
        places_list.filter(place_names__contains = pn)

In the above example the filter doesn't work the way I expect it to. It works as a regular filter and doesn't do the "_contains". The same filter works fine if the type is StringField(). Is it possible to use "_contains" with ListFields? If not is there any way around this? thanks :)

Answer 1

__contains is a string lookup using a regex under the hood. To check if an item is in a listfield you should use the __in however, that does an exact match.

You could denormalise and create a ListField with the place names split into single words and lowercased, then you can use __in to determine if there is a match.