MongoDB: query multiple $elemmatch with $all - node.js

Question

In my app, I have a polls collection and the a document looks like this;
/* POLLS */
{
...
"type": "COMMON",
"__v": {
"$numberInt": "0"
},
"targets": [
{
"code": "city",
"logic": "eq",
"value": "4"
},
{
"code": "city",
"logic": "eq",
"value": "15"
}
]
}
And the targeting key is an array contains of objects of targets.
Each target's code can be city or gender.
So it means, "gender" may not be found in a Poll document.
Depending on that when fetching Polls, I want the ones matching with my User's fields, if the code exists.
For example; When fetching the Polls from a User's feed, If a Poll contains gender targeting, I want to find polls matching with my User's gender.
My code is like this:
Poll.find({
state: "PUBLISHED",
approval: "APPROVED",
$or: [
{
targets: {
$exists: true,
$eq: []
}
},
{
targets: {
$exists: true,
$ne: [],
$all: [
{
$elemMatch: {
code: {
$exists: true,
$eq: "city"
},
value: {
$eq: foundUser.cityCode // equals to 4 in this example
}
}
},
{
$elemMatch: {
code: {
$exists: true,
$eq: "gender"
},
value: {
$eq: foundUser.gender // equals to m in this example
}
}
}
]
}
}
]
})
However, the list returns empty for the Poll document I wrote above.
When the part below commented out, the code returns the correct polls.
Poll.find({
state: "PUBLISHED",
approval: "APPROVED",
$or: [
{
targets: {
$exists: true,
$eq: []
}
},
{
targets: {
$exists: true,
$ne: [],
$all: [
{
$elemMatch: {
code: {
$exists: true,
$eq: "city"
},
value: {
$eq: foundUser.cityCode // equals to 4 in this example
}
}
},
// {
// $elemMatch: {
// code: {
// $exists: true,
// $eq: "gender"
// },
// value: {
// $eq: foundUser.gender // equals to m in this example
// }
// }
// }
]
}
}
]
})
May anyone help me with the situation that return the right polls when gender or country targeted?
Thanks, Onur.

Answer 1

Return targets field is an array whose elements match the $elemMatch criteria in array
Try that query
Poll.find({
state: "PUBLISHED",
approval: "APPROVED",
$or: [
{
targets: {
$exists: true,
$eq: []
}
},
{
targets: {
$exists: true,
$ne: [],
$all: [
{
$elemMatch: {
code: {
$exists: true,
$eq: "city"
},
value: {
$eq: "4" // equals to 4 in this example
}
}
}
]
}
},
{
targets: {
$exists: true,
$ne: [],
$all: [
{
$elemMatch: {
code: {
$exists: true,
$eq: "gender"
},
value: {
$eq: 'm' // equals to m in this example
}
}
}
]
}
}
]
})