在pymongo中选择*在MongoDB中限制100个等效项

Question

I am very new to MongoDB and using jupyter notebook for extracting data from mongodb. I am trying to fetch first 100 documents in MongoDB and i do have a crude way of fetching only 100 documents which is to add a counter and stop at 100th counter.

#import library
import pymongo
from pymongo import MongoClient

#connect with mongo client
client = MongoClient('myipaddress', 27011)

db = client.mydatabase_test
collection = db.mycollection_in_testdatabase

#start counter
i=0
for obj in collection.find():
    if i <= 100:
        print obj['dummy_column']
        i = i+1
    else:
        break

Is there any better way to do this in mongodb? I am sure there must be some equivalent of select * from mydb limit 100 in mongodb. Can anyone help?

Answer 1

As Yogesh said , you should use limit .
eg

cursor = collection.find().limit(100)

Now that you have created cursor you can extract some field like this:

something = []  # list for storing your 100 values of field dummy_column

for doc in cursor:   # loop through these 100 entries 

    something.append(doc.get('dummy_column', '')) # append to this list vallue of field **dummy_column**