Find all documents where the array elements matches some conditions in reactivemongo - mongodb

Question

In my MongoDB database I've a collection named "recommendation.users" in which i store all the User data.
A document of my collection has the following form:
{
"_id" : ObjectId("542e67e07f724fc2af28ba75"),
"id" : "",
"email" : "luigi#gmail.com",
"tags" : [
{
"tag" : "Paper Goods:Liners - Baking Cups",
"weight" : 2,
"lastInsert" : 1412327492874
},
{
"tag" : "Vegetable:Carrots - Jumbo",
"weight" : 4,
"lastInsert" : 1412597883569
},
{
"tag" : "Paper Goods:Lialberto- Baking Cups",
"weight" : 1,
"lastInsert" : 1412327548205
},
{
"tag" : "Fish:Swordfish Loin Portions",
"weight" : 3,
"lastInsert" : 1412597939124
},
{
"tag" : "Vegetable:Carrots - alberto#gmail.com",
"weight" : 2,
"lastInsert" : 1412597939124
}
]
}
As driver I'm using ReactiveMongo in Scala.
Now I'm writing a method that get a tags: List[String] and search in my collections all the Users where the "tags" elements contains all the value passed as parameter.
In other words i want to find all the documents where the "tags" tag contains documents where "tag" = tags(i) for every element of tags.
How can I make something like this in MongoDB and reactiveMongo??
My method has the following signature:
def findUsers(tags: List[String]): Future[Option[List[User]]] = {
//search all the matching Users
//if exists at least one User return a Some(List(users))
//otherwise returns a None
}
For example if i had the following two documents in my collection:
[
{
"_id" : ObjectId("542e67e07f724fc2af28ba75"),
"id" : "",
"email" : "luigi#gmail.com",
"tags" : [
{
"tag" : "Paper Goods:Liners - Baking Cups",
"weight" : 2,
"lastInsert" : 1412327492874
},
{
"tag" : "Vegetable:Carrots - Jumbo",
"weight" : 4,
"lastInsert" : 1412597883569
},
{
"tag" : "Paper Goods:Lialberto- Baking Cups",
"weight" : 1,
"lastInsert" : 1412327548205
},
{
"tag" : "Fish:Swordfish Loin Portions",
"weight" : 3,
"lastInsert" : 1412597939124
},
{
"tag" : "Vegetable:Carrots - alberto#gmail.com",
"weight" : 2,
"lastInsert" : 1412597939124
}
]
},
{
"_id" : ObjectId("542e67e07f724fc2af28ba75"),
"id" : "",
"email" : "alberto#gmail.com",
"tags" : [
{
"tag" : "Paper Goods:Lialberto- Baking Cups",
"weight" : 1,
"lastInsert" : 1412327548205
},
{
"tag" : "Fish:Swordfish Loin Portions",
"weight" : 3,
"lastInsert" : 1412597939124
},
{
"tag" : "Vegetable:Carrots - alberto#gmail.com",
"weight" : 2,
"lastInsert" : 1412597939124
}
]
}]
If my method is called with findUser(List("Fish:Swordfish Loin Portions", "Vegetable:Carrots - alberto#gmail.com")) my method had to returns the first User.
I know that is possible to do that with a cycle that check if a user had all the given tags, but it's too complicated and verbose. Exists an alternative??
How can I make that??

Answer 1

Use query like
db.test.find({$and:[{"tags.tag":"a"},{"tags.tag":"b"}]})
And you may simplify your life by using this reactivemongo-query https://github.com/sh1ng/ReactiveMongo-Queries
val cursor = collection.find(on[Interests].and(_.eq(_.tags.tag, "Fish:Swordfish Loin Portions"), _.eq(_.tags.tag, "Vegetable:Carrots - alberto#gmail.com"))).cursor[Interests]
Of course you may rewrite it in pure reactivemongo.