pymongo or mongo solution to list all keys in a collection

Question

I've seen this answer, and am familiar with variety.js

...but I'm wondering if there's any inbuilt mongo command to easily list all the keys in a mongo db collection---the same way I can show dbs, and show collections, it would be great if once within a collection I could "show keys." I use variety.js for overall statistics, but it's a little slow, and sometimes I just want the list of keys.

If this functionality does not exist, what's the easiest, fastest, or most compact way to get this list? (It'd be great to get all 3 solutions with some comparison!)

Do you need keys from all subdocuments too? Or just the first level there `_id` is? — alecxe, Jun 17 '13 at 17:48
Does [this](http://stackoverflow.com/a/2308036/771848) work for you? — alecxe, Jun 17 '13 at 18:24
Those seem to point toward variety, even the changed answer that includes nested keys? — Mittenchops, Jun 17 '13 at 18:27
Yeah, when it comes to subdocuments it becomes even more complicated, and, yes, these threads points toward `variety`. — alecxe, Jun 17 '13 at 18:34

score 2 · Answer 1 · edited Mar 20 '19 at 17:19

Had/have a similar question. Came up with this less than elegant solution in the mean time, using Python 3.4 and Pymongo (thus assumes the argument "collection" is an iterator full of dicts).

This is minimally tested:

def find_all_keys(collection):
    def find_keys_in_doc(doc, pre=""):
        found_keys = []
        append = found_keys.append

        for k,v in doc.items():
            if type(v) is dict:
                found_keys += find_keys_in_doc(v, pre=pre+k+".")
            else:
                append(k)

        return found_keys

    all_keys = []

    for doc in collection:
        all_keys += find_keys_in_doc(doc)

    return sorted(set(all_keys))

You correctly formatted you code! So I took out your apology. — msanford, Mar 10 '17 at 20:19

score 0 · Accepted Answer · answered Jul 22 '13 at 18:09

0

As of July 22, 2013, there is no mongodb-native way of accomplishing this. You'll need to use variety.js.

answered Jul 22 '13 at 18:09

Mittenchops

18,633
33
128
246

score 0 · Answer 3 · answered Aug 13 '17 at 19:41

0

I do

db.users.find({}).limit(1).map(docs  => Object.keys(docs))

answered Aug 13 '17 at 19:41

zarehb

21
7

score 0 · Answer 4 · answered Aug 13 '19 at 12:29

Try to achieve the same goal. I use Python 3.x and Pymongo.

My solution work for nested dict and nested list (amazing uh ?)

This function return a list of string that contains all path.

Let's take this nested mongo document :

{
    "_id" : ObjectId("5d5166ab7773870c1e57c638"),
    "eventId" : NumberLong(1),
    "estimatedCharacterization" : {
        "snrVerticalAxis" : 5.0,
        "snrHorizontalAxis" : 5.0,
        "distance" : 0.0,
        "magnitude" : 0.0
    },
    "definition" : {
        "requestType" : "DUST_DEVIL",
        "requestedChannels" : [ 
            {
                "startTime" : {
                    "utc" : ISODate("2003-06-25T22:35:37.000Z"),
                    "utcString" : "2003-176T22:35:37.000",
                    "lmst" : "-5482T10:06:09.956",
                    "sclk" : NumberLong(109852537000),
                    "lobt" : NumberLong(112493764823),
                    "aobt" : NumberLong(109857192936)
                },
                "endTime" : {
                    "utc" : ISODate("2003-06-26T05:27:27.000Z"),
                    "utcString" : "2003-177T05:27:27.000",
                    "lmst" : "-5482T16:46:58.822",
                    "sclk" : NumberLong(109877247000),
                    "lobt" : NumberLong(112519067586),
                    "aobt" : NumberLong(109881902665)
                },
                "minDwnSamplRate" : 0.05
            }
        ]
    },
}

with my code will return :

eventId
estimatedCharacterization.snrVerticalAxis
estimatedCharacterization.snrHorizontalAxis
estimatedCharacterization.distance
estimatedCharacterization.magnitude
definition.requestType
definition.requestedChannels.XX.minDwnSamplRate
definition.requestedChannels.XX.startTime.utc
definition.requestedChannels.XX.startTime.utcString
definition.requestedChannels.XX.startTime.lmst
definition.requestedChannels.XX.startTime.sclk
definition.requestedChannels.XX.startTime.lobt
definition.requestedChannels.XX.startTime.aobt
definition.requestedChannels.XX.endTime.utc
definition.requestedChannels.XX.endTime.utcString
definition.requestedChannels.XX.endTime.lmst
definition.requestedChannels.XX.endTime.sclk
definition.requestedChannels.XX.endTime.lobt
definition.requestedChannels.XX.endTime.aobt

Here is the code (based on code of other comment, because he was very clear) :

def find_all_keys(collection):
    def find_keys_in_doc(doc, pre=""):
        found_keys = []
        append = found_keys.append
        if isinstance(doc, dict):
            for k,v in doc.items():
                if isinstance(v, dict):
                    found_keys += find_keys_in_doc(v, pre=pre+k+".")
                elif isinstance(v, list):
                    found_keys += find_keys_in_doc(v, pre=pre+k+".")
                else:
                    append(pre + k)
        elif isinstance(doc, list):
            for v in doc:
                if isinstance(v, dict):
                    found_keys += find_keys_in_doc(v, pre=pre+"XX"+".")
                elif isinstance(v, list):
                    found_keys += find_keys_in_doc(v, pre=pre+"XX"+".")
                else:
                    append(pre + str(v))

        return found_keys
    all_keys = []
    for doc in collection:
        all_keys += find_keys_in_doc(doc)
    return sorted(set(all_keys))

Have fun :)

pymongo or mongo solution to list all keys in a collection

4 Answers4