How to update values using pymongo?

Question

I've a mongodb collection in this form:

{id=ObjectId(....),key={dictionary of values}}
where dictionary of values is {'a':'1','b':'2'.....}

Let dictionary of values be 'd'. I need to update the values of the key in the 'd'. i.e I want to change 'a':'1' to 'a':'2' How can do I this in pymongo?

Code goes something like this:

productData is a collection in mongoDB
for p in productData.find():
     for k,v in p.iteritems():
         value=v['a']
         value=value+1
         v['a']=value

Now reflect the new value in the productData.

This is what I've tried and it introduces a new key-value pair instead of updating the

for p in productData.find():
    for k,v in p.iteritems():
         value=v['a']
         value=value+1
         v['a']=value
         productData.update({'_id':mongoId},{"$set":{'d.a':'100'}},upsert=False)

Duplicate of http://stackoverflow.com/questions/4372797/how-do-i-update-a-mongo-document-after-inserting-it — jdotjdot, Dec 04 '12 at 19:56
For one you should be doing "for k,v in p['d'].iteritems()" - also, Mark's answer below does work without creating a new key/value pair. You should post more code so we can see what you are doing wrong. — IamAlexAlright, Dec 04 '12 at 23:13

Mark Unsworth · Accepted Answer · 2015-07-28T13:17:22.400

You can use the $set syntax if you want to set the value of a document to an arbitrary value. This will either update the value if the attribute already exists on the document or create it if it doesn't. If you need to set a single value in a dictionary like you describe, you can use the dot notation to access child values.

If p is the object retrieved:

existing = p['d']['a']

For pymongo versions < 3.0

db.ProductData.update({
  '_id': p['_id']
},{
  '$set': {
    'd.a': existing + 1
  }
}, upsert=False, multi=False)

For pymongo versions >= 3.0

db.ProductData.update_one({
  '_id': p['_id']
},{
  '$set': {
    'd.a': existing + 1
  }
}, upsert=False)

However if you just need to increment the value, this approach could introduce issues when multiple requests could be running concurrently. Instead you should use the $inc syntax:

For pymongo versions < 3.0:

db.ProductData.update({
  '_id': p['_id']
},{
  '$inc': {
    'd.a': 1
  }
}, upsert=False, multi=False)

For pymongo versions >= 3.0:

db.ProductData.update_one({
  '_id': p['_id']
},{
  '$inc': {
    'd.a': 1
  }
}, upsert=False)

This ensures your increments will always happen.

There are missing `}` in both update statements at the `$set` and `$inc` part. — Eleni, Jun 04 '13 at 09:52
`$set` should be quoted: `'$set'`. Otherwise it throws syntax error. — franzlorenzon, Sep 18 '13 at 11:16

score 10 · Answer 2 · edited Feb 13 '18 at 22:51

10

With my pymongo version: 3.2.2 I had do the following

from bson.objectid import ObjectId
import pymongo

client = pymongo.MongoClient("localhost", 27017)
db = client.mydbname

db.ProductData.update_one({
  '_id': ObjectId(p['_id']['$oid'])
},{
  '$set': {
    'd.a': existing + 1
  }
}, upsert=False)

edited Feb 13 '18 at 22:51

user6039980

3,108
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answered Mar 29 '16 at 04:19

Ahsan

3,845
2
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faced with TypeError Exception Value: Object of type 'ObjectId' is not JSON serializable on django1.11 – Yuseferi Nov 10 '17 at 19:58

score 2 · Answer 3 · answered Nov 05 '19 at 15:30

2

Something I did recently, hope it helps. I have a list of dictionaries and wanted to add a value to some existing documents.

for item in my_list:
    my_collection.update({"_id" : item[key] }, {"$set" : {"New_col_name" :item[value]}})

answered Nov 05 '19 at 15:30

Jack

394
1
15

1

`DeprecationWarning: update is deprecated. Use replace_one, update_one or update_many instead.` – alper Oct 11 '21 at 13:50

score 0 · Answer 4 · edited Apr 23 '21 at 09:53

0

In Python, the operators (e.g., $set) should be in quotes:

db.ProductData.update(
    {'fromAddress': 'http://localhost:7000/'},
    {'$set': {'fromAddress': 'http://localhost:5000/'}},
    {'multi': True}
)

edited Apr 23 '21 at 09:53

heilala

770
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answered Jul 05 '18 at 16:14

Adarsh R

65
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5

How to update values using pymongo?

4 Answers4

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