MongoDB query using values priority - mongodb

Question

I have following documents in my collection:
/* 1 */
{
"_id" : ObjectId("5ea32d11f213c27c35395fd3"),
"name" : "Test",
"state" : "OH",
"code" : "CDM"
}
/* 2 */
{
"_id" : ObjectId("5ea32d29f213c27c35395fe0"),
"name" : "Test1",
"state" : "ALL",
"code" : "CDM"
}
/* 3 */
{
"_id" : ObjectId("5ea32d38f213c27c35395fe7"),
"name" : "Test2",
"state" : "OH",
"code" : "ALL"
}
/* 4 */
{
"_id" : ObjectId("5ea32d46f213c27c35395feb"),
"name" : "Test3",
"state" : "ALL",
"code" : "ALL"
}
Trying to filter documents based on state and code.
But there are few criteria if particular state or code is not found then search with value ALL
Example 1:
state = CA
code = CDM
then return only
{
"_id" : ObjectId("5ea32d29f213c27c35395fe0"),
"name" : "Test1",
"state" : "ALL",
"code" : "CDM"
}
Example 2:
state = CA
code = DCM
then return only
{
"_id" : ObjectId("5ea32d46f213c27c35395feb"),
"name" : "Test3",
"state" : "ALL",
"code" : "ALL"
}
etc..
The query that i tried was state = CA ,code = CDM:
db.getCollection('user_details').aggregate([
{'$match': { 'state': {'$in': ['CA','ALL']},
'code': {'$in': ['CDM','ALL']}}}
])
return was:
/* 1 */
{
"_id" : ObjectId("5ea32d29f213c27c35395fe0"),
"name" : "Test1",
"state" : "ALL",
"code" : "CDM"
}
/* 2 */
{
"_id" : ObjectId("5ea32d46f213c27c35395feb"),
"name" : "Test3",
"state" : "ALL",
"code" : "ALL"
}
Expected was :
{
"_id" : ObjectId("5ea32d29f213c27c35395fe0"),
"name" : "Test1",
"state" : "ALL",
"code" : "CDM"
}
Could you help to solve this issue.

Answer 1

Try below query :
db.collection.find({
$or: [
{
state: "CA",
code: "CDM"
},
{
state: "ALL",
code: "CDM"
},
{
state: "ALL",
code: "ALL"
},
{
state: "CA",
code: "ALL"
}
]
})
So basically you can not achieve what you're looking for in one query, you can try aggregation operator $facet & $switch to do this but I would not prefer to do that cause each stage in facet will do the given operation on entire collection's data. Instead get fewer docs using above query & in your code you can actually filter for best suited doc, Which would be easy & efficient. Don't forget to maintain indexes on DB.
Test : mongoplayground

Answer 2

Try this one:
db.user_details.aggregate([
{
$facet: {
match: [
{
"$match": {
$or: [
{
"state": "CA",
"code": {
"$in": [ "CDM", "ALL" ]
}
},
{
"state": {
"$in": [ "CA", "ALL"]
},
"code": "CDM"
}
]
}
}
],
all: [
{
"$match": {
"state": "ALL",
code: "ALL"
}
}
]
}
},
{
$project: {
match: {
$cond: [
{
$eq: [ { $size: "$match" }, 0]
},
"$all",
"$match"
]
}
}
},
{
$unwind: "$match"
},
{
$replaceWith: "$match"
}
])
MongoPlayground