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MongoDB - Querying a nested boolean field

I have the following mongoclient query:
db = db.getSiblingDB("test-db");
hosts = db.getCollection("test-collection")
db.hosts.aggregate([
{$match: {"ip_str": {$in: ["52.217.105.116"]}}}
]);
Which outputs this:
{
"_id" : ObjectId("..."),
"ip_str" : "52.217.105.116",
"data" : [
{"ssl" : {"cert" : {"expired" : "False"}}}
]
}
I'm trying to build the query so it returns a boolean True or False depending on the value of the ssl.cert.expired field. I'm not quite sure how to do this though. I've had a look into the $lookup and $where operators, but am not overly familiar with querying nested objects in Mongo yet.

As the data is an array, in order to get the (first) element of the nested expired, you should work with $arrayElemAt and provide an index as 0 to indicate the first element.
{
$project: {
ip_str: 1,
expired: {
$arrayElemAt: [
"$data.ssl.cert.expired",
0
]
}
}
}
Demo # Mongo Playgound

pymongo - Update a data and access the found value

I am trying to update a value of an array stored in a mongodb collection
any_collection: {
{
"_id": "asdw231231"
"values": [
{
"item" : "a"
},
{
"item" : "b"
}
],
"role": "role_one"
},
...many similar
}
the idea is that I want to access values ​​and edit a value with the following code that I found in the mongodb documentation
conn.any_collection.find_one_and_update(
{
"_id": any_id,
"values.item": "b"
},
{
"$set": {
"values.$.item": "new_value" # here the error, ".$."
}
}
)
This should work, but I can't understand what the error is or what is the correct syntax for pymongo. The error is generated when adding "$";

It works fine with my fastAPI.
#app.get("/find/{id}")
async def root(id: int):
db = get_database()
q = {'_id': 'asdw231231','values.item': 'b'}
u = {'$set': {'values.$.item': 'new_value' }}
c = db['any'].find_one_and_update(q, u)
return {"message": c}
mongoplayground

How to use find() nested documents for two levels or more?

Here is my sample mongodb database
database image for one object
The above is a database with an array of articles. I fetched only one object for simplicity purposes.
database image for multiple objects ( max 20 as it's the size limit )
I have about 18k such entries.
I have to extract the description and title tags present inside the (articles and 0) subsections.
The find() method is the question here.. i have tried this :
for i in db.ncollec.find({'status':"ok"}, { 'articles.0.title' : 1 , 'articles.0.description' : 1}):
for j in i:
save.write(j)
After executing the code, the file save has this :
_id
articles
_id
articles
and it goes on and on..
Any help on how to print what i stated above?
My entire code for reference :
import json
import newsapi
from newsapi import NewsApiClient
import pymongo
from pymongo import MongoClient
client = MongoClient()
db = client.dbasenews
ncollec = db.ncollec
newsapi = NewsApiClient(api_key='**********')
source = open('TextsExtractedTemp.txt', 'r')
destination = open('NewsExtracteddict.txt', "w")
for word in source:
if word == '\n':
continue
all_articles = newsapi.get_everything(q=word, language='en', page_size=1)
print(all_articles)
json.dump(all_articles, destination)
destination.write("\n")
try:
ncollec.insert(all_articles)
except:
pass

Okay, so I checked a little to update my rusty memory of pymongo, and here is what I found.
The correct query should be :
db.ncollec.find({ 'status':"ok",
'articles.title' : { '$exists' : 'True' },
'articles.description' : { '$exists' : 'True' } })
Now, if you do this :
query = { 'status' : "ok",
'articles.title' : { '$exists' : 'True' },
'articles.description' : { '$exists' : 'True' } }
for item in db.ncollect.find(query):
print item
And that it doesn't show anything, the query is correct, but you don't have the right database, or the right tree, or whatever.
But I assure you, that with the database you showed me, that if you do...
query = { 'status' : "ok",
'articles.title' : { '$exists' : 'True' },
'articles.description' : { '$exists' : 'True' } }
for item in db.ncollect.find(query):
save.write(item[0]['title'])
save.write(item[0]['description'])
It'll do what you wished to do in the first place.
Now, the key item[0] might not be good, but for this, I can't really be of any help since it is was you are showing on the screen. :)
Okay, now. I have found something for you that is a bit more complicated, but is cool :)
But I'm not sure if it'll work for you. I suspect you're giving us a wrong tree, since when you do .find( {'status' : 'ok'} ), it doesn't return anything, and it should return all the documents with a 'status' : 'ok', and since you have lots...
Anyways, here is the query, that you should use with .aggregate() method, instead of .find() :
elem = { '$match' : { 'status' : 'ok', 'articles.title' : { '$exists' : 'True'}, 'articles.description' : { '$exists' : 'True'}} }
[ elem, { '$unwind' : '$articles' }, elem ]
If you want an explanation as to how this works, I invite you to read this page.
This query will return ONLY the elements in your array that have a title, and a description, with a status OK. If an element doesn't have a title, or a description, it will be ignored.

Pymongo count elements collected out of all documents with key

I want to count all elements which occur in somekey in an MongoDB collection.
The current code looks at all elements in somekey as a whole.
from pymongo import Connection
con = Connection()
db = con.database
collection = db.collection
from bson.code import Code
reducer = Code("""
function(obj, prev){
prev.count++;
}
""")
from bson.son import SON
results = collection.group(key={"somekey":1}, condition={}, initial={"count": 0}, reduce=reducer)
for doc in results:
print doc
However, I want that it counts all elements which occur in any document with somekey.
Here is an anticipated example. The MongoDB has the following documents.
{ "_id" : 1, “somekey" : [“AB", “CD"], "someotherkey" : "X" }
{ "_id" : 2, “somekey" : [“AB", “XY”], "someotherkey" : "Y" }
The result should provide an by count ordered list with:
count: 2 "AB"
count: 1 "CD"
count: 1 "XY"

The .group() method will not work on elements that are arrays, and the closest similar thing would be mapReduce where you have more control over the emitted keys.
But really the better fit here is the aggregation framework. It is implemented in native code as does not use JavaScript interpreter processing as the other methods there do.
You wont be getting an "ordered list" from MongoDB responses, but you get a similar document result:
results = collection.aggregate([
# Unwind the array
{ "$unwind": "somekey" },
# Group the results and count
{ "$group": {
"_id": "$somekey",
"count": { "$sum": 1 }
}}
])
Gives you something like:
{ "_id": "AB", "count": 2 }
{ "_id": "CD", "count": 1 }
{ "_id": "XY", "count": 1 }

How to update an already retrieved document?

I'm retrieving a document like this:
user = db.users.find_one( { '_id' : ObjectId( 'anID' ) } )
But I can't figure out how to update the document if I want to change the value of 'gender'. This doesn't work:
newValue = {
'gender' : gender
}
db.users.update( user, newValue, False )
Is my syntax wrong? What's the best way to update user

Your update syntax is not correct, it should be:
update(spec, document, upsert=False, multi=False, ...)
Where spec is the same filter that you used for the find, i.e. { '_id' : ObjectId( 'anID' ) }
You can either update the document by replacing it with a modified document or use a targeted update to change only a certain value. The advantage of the targeted update is that it saves you the first round trip to the server to get the user document.
Replacement update:
user = db.users.find_one( { '_id' : ObjectId( 'anID' ) } )
user['gender'] = newGender
db.users.update( { '_id' : user['_id'] }, user, False)
Targeted update:
db.users.update( { '_id' : ObjectId( 'anID' ) }, \
{ '$set': { 'gender' : newGender } }, False )

If you don't want to replace the entire document you should use the $set operator as:
db.users.update( { '_id': user['_id'] }, { '$set': newValue }, False )