build dynamic MongoDB query to update nested value in dict - mongodb

Question

Considering an object as such:
{
"_id" : ObjectId("5b4dbf3541e5ae6de394cc99"),
"active" : true,
"email" : "admin#something.eu",
"password" : "$2b$12$5qqD3ZulKI7S6j.Wx513POpCNWRMppE.vY4.3EIZedm109VUPqXoi",
"badges" : {
"cnc" : {
"lvl" : "0"
},
"laser" : {
"lvl" : "0"
},
"impression3d" : {
"lvl" : "0"
},
"maker" : {
"lvl" : "0"
},
"electronique" : {
"lvl" : "0"
},
"badge" : {
"lvl" : 1
}
},
"roles" : [
ObjectId("5b4dbf3541e5ae6de394cc97")
]
}
I need to change the lvl value to anywhere between 0 and 5, not necessarily inregular increments. To do this, the parent object name is passed by a variable, thererfor I'm trying to build a dynamic query for a badge lvl to be changed.
Currently the end of my Flask route looks as so:
badge = quiz['badge']
C_user = current_user.get_id()
update = bdd.user.update({"_id": C_user, "badges": { '$elemMatch': {badges : badge}}}, {"$set": { "badges.$.lvl": 3 }}, upsert = True)
But with a query of this sort, I receive an error saying:
pymongo.errors.WriteError: The positional operator did not find the match needed from the query.
Am I totally wrong thinking I need to use the $elemMatch operator? Is there a way to dynamically target the different badges to increment the inner lvl?
Thank you!
Note: I first attempted this with MongoEngine but it seemed impossible to drill down with it.

Answer 1

you cannot do this, badges is an document, not an array. try
...
{"$set": { "badges.badge.lvl": 3 }}
...
But you'll have to explicitely do this for each badges fields.
The way to use your query is to update your scheme in something like
...
"badges" : [
{name:"cnc",
"lvl" : "0"
},
{"name":"laser",
"lvl" : "0"},
...
]
...
EDIT : with some updates on your scheme, here's a way to reach your goal :
New datata Schema :
{
"_id" : ObjectId("5b4dbf3541e5ae6de394cc99"),
"active" : true,
"email" : "admin#something.eu",
"password" : "$2b$12$5qqD3ZulKI7S6j.Wx513POpCNWRMppE.vY4.3EIZedm109VUPqXoi",
"badges" : [
{
"name" : "cnc",
"lvl" : "0"
},
{
"name" : "laser",
"lvl" : "5"
},
{
"name" : "impression3d",
"lvl" : "0"
},
{
"name" : "maker",
"lvl" : "0"
},
{
"name" : "electronique",
"lvl" : "0"
},
{
"name" : "badge",
"lvl" : 1
}
],
"roles" : [
ObjectId("5b4dbf3541e5ae6de394cc97")
]
}
and here an update query :
db['02'].update(
{_id: ObjectId("5b4dbf3541e5ae6de394cc99")}, // <= here you filter your documents
{ $set: { "badges.$[elem].lvl": "10" } }, // <= use of positionnal operator with identifier, needed for arrayFilters. elem is arbitraty
{ arrayFilters: [ { "elem.name": "laser" } ], // <= update only elements in array that match arrayFilters.
upsert: true }
)