mongodb: issues using $lte and $gte - mongodb

Question

look at this bizarre result:
list(db.users.find({"produit_up.spec.prix":{"$gte":0, "$lte": 1000}}, {"_id":0,"produit_up":1}))
Out[5]:
[{u'produit_up': [{u'avatar': {u'avctype': u'image/jpeg',
u'orientation': u'portrait',
u'photo': ObjectId('506867863a5f3a0ea84dcd6c')},
u'spec': {u'abus': 0,
u'date': u'2012-09-30',
u'description': u"portable tr\xe8s solide, peu servi, avec batterie d'une autonomie de 3 heures.",
u'id': u'alucaard134901952647',
u'namep': u'nokia 3310',
u'nombre': 1,
u'prix': 1000,
u'tags': [u'portable', u'nokia', u'3310'],
u'vendu': False}},
{u'avatar': {u'avctype': u'image/jpeg',
u'orientation': u'portrait',
u'photo': ObjectId('50686d013a5f3a04a8923b3e')},
u'spec': {u'abus': 0,
u'date': u'2012-09-30',
u'description': u'\u0646\u0628\u064a\u0639 \u0623\u064a \u0641\u0648\u0646 \u062c\u062f\u064a\u062f \u0641\u064a \u0627\u0644\u0628\u0648\u0627\u0637 \u0645\u0639\u0627\u0647 \u0634\u0627\u0631\u062c\u0648\u0631 \u062f\u0648\u0631\u064a\u062c \u064a\u0646',
u'id': u'alucaard134902092967',
u'namep': u'iphone 3gs',
u'nombre': 1,
u'prix': 20000,
u'tags': [u'iphone', u'3gs', u'apple'],
u'vendu': False}},
{u'avatar': {u'avctype': u'image/jpeg',
u'orientation': u'paysage',
u'photo': ObjectId('50686d3e3a5f3a04a8923b40')},
u'spec': {u'abus': 0,
u'date': u'2012-09-30',
u'description': u'vends 206 toutes options 2006 hdi.',
u'id': u'alucaard134902099082',
u'namep': u'peugeot 206',
u'nombre': 1,
u'prix': 500000,
u'tags': [u'voiture', u'206', u'hdi'],
u'vendu': False}}]}]
list(db.users.find({"produit_up.spec.prix":{"$gte":0, "$lte": 100}}, {"_id":0,"produit_up":1}))
Out[6]: []
pymongo.version
Out[8]: '2.3+'
and it gives me the same result in Mongo Shell:
db.version()
2.2.0

Answer 1

here is the answer from Bernie Hackett
You have three values for "produit_up.spec.prix", 1000, 20000, 500000.
Why would you think that {"$gte":0, "$lte": 100} would match any of
those values? 100 is less than all of those values.
The reason that {"$gte":0, "$lte": 1000} returns all three documents
is that they are all subdocuments in an array. Since one of the
subdocuments in the array is matched the entire enclosing document
is a match for your query. Since you did a projection on only
"produit_up", just that array (including all array members) is
returned. Use $elemMatch in MongoDB 2.2 to only return the exact
matching array element.
MongoDB and PyMongo are working as designed here.
To get the behavior I think you're asking for see the $elemMatch operator:
http://docs.mongodb.org/manual/reference/projection/elemMatch/