Append item to MongoDB document array in PyMongo without re-insertion
Just to add to @ssytvane answer,and to answer @Guarav: you can add "upsert = True" if it does not exist:
def update_tags(ref, new_tag):
coll.update({'ref': ref}, {'$push': {'tags': new_tag}}, upsert = True)
or
def update_tags(ref, new_tag):
coll.update_one({'ref': ref}, {'$push': {'tags': new_tag}}, upsert = True)
You can simply do
1) If you want to append single entry
def update_tags(ref, new_tag):
coll.update({'ref': ref}, {'$push': {'tags': new_tag}})
eg:
{
"_id" : ObjectId("561c199e038e42b10956e3fc"),
"tags" : [ "tag1", "tag2", "tag3" ],
"ref" : "4780"
}
>> update_tags("4780", "tag4")
{'updatedExisting': True, u'nModified': 1, u'ok': 1, u'n': 1}
>> coll.find_one({"ref":"4780"})
{
"_id" : ObjectId("561c199e038e42b10956e3fc"),
"tags" : [ "tag1", "tag2", "tag3" , "tag4" ],
"ref" : "4780"
}
2) If you want to append multiple entries
def update_tags(ref, new_tag):
coll.update({'ref': ref}, {'$pushAll': {'tags': new_tag}}) #type of new_tag is list
eg:
{
"_id" : ObjectId("561c199e038e42b10956e3fc"),
"tags" : [ "tag1", "tag2", "tag3" ],
"ref" : "4780"
}
>> update_tags("4780", ["tag5", "tag6", "tag7"])
{'updatedExisting': True, u'nModified': 1, u'ok': 1, u'n': 1}
>> coll.find_one({"ref":"4780"})
{
"_id" : ObjectId("561c199e038e42b10956e3fc"),
"tags" : [ "tag1", "tag2", "tag3" , "tag4" , "tag5", "tag6", "tag7" ],
"ref" : "4780"
}
Note: If the key is not already present, then mongo will create new key.
You don't need to use to retrieve the document first just use the .update
method with the $push
operator.
def update_tags(ref, new_tag):
coll.update({'ref': ref}, {'$push': {'tags': new_tag}})
Since update is deprecated you should use the find_one_and_update
or the update_one
method if you are using pymongo 2.9 or newer