I got a database with this info:
{"_id":1, "test":6,"foo":[{"mom":5,"dad":10},{"mom":7, "dad":12}]}
{"_id":2, "test":9,"foo":[{"mom":6,"dad":20},{"mom":7, "dad":15}]}
{"_id":3, "test":10, "foo":[{"mom":10,"dad":13},{"mom":2, "dad":19}]}
and i query in mongo from db with mom=7:
cursor = foo.find({"foo.mom":7},{"foo.$":1,"_id":0, "test":1})
for key in cursor:
print key
it prints me this:
{"test":6,"foo":[{"mom":7, "dad":12}]}
{"test":9,"foo":[{"mom":7, "dad":15}]}
if i use
print key['test']
i'll get the result of only "test"
So, the question is: how can i get the result like this:
{"test":6,"foo":[{"dad":12}]}
{"test":9,"foo":[{"dad":15}]}
i tried to use
print key["foo.dad"]
but it only returns an error
As the value of "foo" is saved in an array, you need to use key['foo'][0]['dad'] to print the value of 'dad' from the result.
The code I used is like this:
cursor = foo.find({"foo.mom":7},{"foo.$":1,"_id":0, "test":1})
for key in cursor:
print key
print key['test']
print key['foo'][0]['dad']
And the result I got is like this:
{u'test': 6.0, u'foo': [{u'dad': 12.0, u'mom': 7.0}]}
6.0
12.0
{u'test': 9.0, u'foo': [{u'dad': 15.0, u'mom': 7.0}]}
9.0
15.0
If you want to get the result without the 'mom' field:
{"test":6,"foo":[{"dad":12}]}
{"test":9,"foo":[{"dad":15}]}
you can use the aggregation framework:
db.foo.aggregate([
{ $unwind : "$foo" },
{ $match : { "foo.mom" : 7 }},
{ $project : {
_id : 0,
test : 1,
"foo.dad" : "$foo.dad"
}},
])
And the result is:
{
"result" : [
{
"test" : 6,
"foo" : {
"dad" : 12
}
},
{
"test" : 9,
"foo" : {
"dad" : 15
}
}
],
"ok" : 1
}
Related
I want to retrieve the single value "count "from pymongo DB but it is not working. The image below shows how the data entry is setup.
Here is the call to my Database class to use the db.find_one().
CODE HERE:
filters = {"email": session.get('email')}
returns = {f'words.{today_s}.{self.length - 3}.count': 1}
count_value = Database.find_one_return_one("users", filters, returns)
print({f'words.{today_s}.{self.length - 3}.count':1})
print(count_value)
#staticmethod
def find_one_return_one(collection: str, query: Dict, data: Dict) -> Dict:
return Database.DATABASE[collection].find_one(query, data)
This returns an empty list of dictionaries from the correct data? I want the count value returned.
This is the projection query: {words.20220302.0.count : 1}
This is what is returned:
{'_id': ObjectId('621ee5065d08c44070140df0'), 'words': {'20220302': [{}, {}, {}, {}, {}, {}, {}]}}
What is wrong or is there a better quicker way to retrieve the count value?
The following query projection can be used to get the desired result. Note this worked with MongoDB v5.
A sample document; similar to the one in the question post:
{ _id: 1, words: { fld: [ { a: 1, b: 2 }, { a: 9, b: 100 } ] } }
The expected result is: { "_id" : 1, "words" : { "fld" : { "a" : 9 } } }
The query:
INDEX = 1 # this is the index of the array element
query = { }
projection = {
'words.fld': {
'$arrayElemAt': [
{ '$map': { 'input': '$words.fld', 'in': { 'a': '$$this.a' } } },
INDEX
]
}
}
result = collection.find_one(query, projection)
print(result)
how i make a list from the values inside urban only for type gasolina?
{ ... "fuelUse" : {
"urban" : [
{
"value" : 6.2,
"unit" : "km/l",
"type" : "alcool"
},
{
"value" : 8.9,
"unit" : "km/l",
"type" : "gasolina"
}
],
},
...."fuelUse" : {
"urban" : [
{
"value" : 7.8,
"unit" : "km/l",
"type" : "alcool"
},
{
"value" : 10.4,
"unit" : "km/l",
"type" : "gasolina"
}
],
}
}
the output like: list = [ 8.9 , 10.4 ]
i tried to iterate in that way, but hav key error: 1
for c in cars:
for a in c['fuelUse']['urban']:
list.append(a[1]['value'])
try
list.append(a['value'])
instead of
list.append(a[1]['value'])
Since a is not a list, it is a single object, there is no need for further indexing.
If you would like the value of the second element, which type is gasolina, from each urban, you should loop through them, not the object's inside.
for c in cars:
for a in c['fuelUse']['urban']:
if a['type'] == 'gasolina':
list.append(a['value'])
I am not quite sure as you did not provide the entire data structure but according to your try it could be like this:
output = [x.get("value") for car in cars for x in car.get("fuelUse").get("urban") if x.get("type") == "gasolina"]
I have a structure like this:
{
"id" : 1,
"user" : "somebody",
"players" : [
{
"name" : "lala",
"surname" : "baba",
"player_place" : "1",
"start_num" : "123",
"results" : {
"1" : { ... }
"2" : { ... },
...
}
},
...
]
}
I am pretty new to MongoDB and I just cannot figure out how to extract results for a specific user (in this case "somebody", but there are many other users and each has an array of players and each player has many results) for a specific player with start_num.
I am using pymongo and this is the code I came up with:
record = collection.find(
{'user' : name}, {'players' : {'$elemMatch' : {'start_num' : start_num}}, '_id' : False}
)
This extracts players with specific player for a given user. That is good, but now I need to get specific result from results, something like this:
{ 'results' : { '2' : { ... } } }.
I tried:
record = collection.find(
{'user' : name}, {'players' : {'$elemMatch' : {'start_num' : start_num}}, 'results' : result_num, '_id' : False}
)
but that, of course, doesn't work. I could just turn that to list in Python and extract what I need, but I would like to do that with query in Mongo.
Also, what would I need to do to replace specific result in results for specific player for specific user? Let's say I have a new result with key 2 and I want to replace existing result that has key 2. Can I do it with same query as for find() (just replacing method find with method replace or find_and_replace)?
You can replace a specific result and the syntax for that should be something like this,
assuming you want to replace the result with key 1,
collection.updateOne({
"user": name,
"players.start_num": start_num
},
{ $set: { "players.$.results.1" : new_result }})
Trying to parse a Json structure in python and Adding a new value with key 'cat':
data = []
for x in a:
for y in x['Hp'].values():
for z in y:
for k in z['abc']['xyz']:
for m in data:
det = m['response']
// Some processing with det whose output is stored in s
k['cat'] = s
print x
However when x is print only the last value is being appended onto the whole dictionary, wheras there are different values for s.
Its obvious that the 'cat' key is being overwritten everytime the loop rounds,but can't find a way to make it right
Below is a sample Json structure:
{
"_id" : ObjectId("asdasda156121s"),
"Hp" : {
"bermud" : [
{
"abc" : {
"gfh" : 1,
"fgh" : 0.0,
"xyz" : [
{
"kjl" : "0",
"bnv" : 0,
}
],
"xvc" : "bv",
"hgth" : "INnn",
"sdf" : 0,
}
}
},
{
"abc" : {
"gfh" : 1,
"fgh" : 0.0,
"xyz" : [
{
"kjl" : "0",
"bnv" : 0,
}
],
"xvc" : "bv",
"hgth" : "INnn",
"sdf" : 0,
}
}
},
..
If you want to store all values change
k['cat'] = s
to
if 'cat' in k.keys():
k['cat'] += s
else:
k['cat'] = s
If you want to store only the first one change
k['cat'] = s
to
if 'cat' not in k.keys():
k['cat'] = s
I'm unwinding one field which is an array of date objects, however in some cases there are empty array's which is fine. I'd like the same treatment using a pipeline, but in some cases, I want to filter the results which have an empty array.
pipeline = []
pipeline.append({"$unwind": "$date_object"})
pipeline.append({"$sort": {"date_object" : 1}})
I want to use the pipeline format, however the following code does not return any records:
pipeline.append({"$match": {"date_object": {'$exists': False }}})
nor does the following work:
pipeline.append({"$match": {"date_object": []}})
and then:
results = mongo.db.xxxx.aggregate(pipeline)
I'm also trying:
pipeline.append({ "$cond" : [ { "$eq" : [ "$date_object", [] ] }, [ { '$value' : 0 } ], '$date_object' ] } )
But with this I get the following error:
.$cmd failed: exception: Unrecognized pipeline stage name: '$cond'
However if I query using find such as find({"date_object": []}), I can get these results. How can I make this work with the pipeline.
I've done in MongoDB shell, but it can be translated into Python easily in python language.
Is it your requirements?
I suppose you have such structure:
db.collection.save({foo:1, date_object:[new Date(), new Date(2016,1,01,1,0,0,0)]})
db.collection.save({foo:2, date_object:[new Date(2016,0,16,1,0,0,0),new Date(2016,0,5,1,0,0,0)]})
db.collection.save({foo:3, date_object:[]})
db.collection.save({foo:4, date_object:[new Date(2016,1,05,1,0,0,0), new Date(2016,1,06,1,0,0,0)]})
db.collection.save({foo:5, date_object:[]})
// Get empty arrays after unwind
db.collection.aggregate([
{$project:{_id:"$_id", foo:"$foo",
date_object:{
$cond: [ {"$eq": [{ $size:"$date_object" }, 0]}, [null], "$date_object" ]
}
}
},
{$unwind:"$date_object"},
{$match:{"date_object":null}}
])
// Get empty arrays before unwind
db.collection.aggregate([
{$match:{"date_object.1":{$exists:false}}},
{$project:{_id:"$_id", foo:"$foo",
date_object:{
$cond: [ {"$eq": [{ $size:"$date_object" }, 0]}, [null], "$date_object" ]
}
}
},
{$unwind:"$date_object"}
])
Only empty date_object
[
{
"_id" : ObjectId("56eb0bd618d4d09d4b51087a"),
"foo" : 3,
"date_object" : null
},
{
"_id" : ObjectId("56eb0bd618d4d09d4b51087c"),
"foo" : 5,
"date_object" : null
}
]
At the end, if you need only empty date_object, you don't need to aggregate, you can easely achieve it with find:
db.collection.find({"date_object.1":{$exists:false}},{date_object:0})
Output
{
"_id" : ObjectId("56eb0bd618d4d09d4b51087a"),
"foo" : 3
}
{
"_id" : ObjectId("56eb0bd618d4d09d4b51087c"),
"foo" : 5
}