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I'm just getting to know the possibilities of Kotlin and mongoDB.
I am writing a method that returns the name of the street after the ID.
Everything works, but I find it quite sloppy.
Empty String initialization, returning more data from the collection than I would like. How do I straighten it? Could it be made into some expression body one-liner?

    fun getStreetNameByStreetId(id: String): String {
    val query = Query()
    query.fields().include("name")
    query.addCriteria(Criteria.where("_id").`is`(id))
    var streetName = ""
    mongoTemplate.executeQuery(
        query, STREET_COLLECTION
    ) { document: Document ->
        streetName = document.getValue("name").toString()
    }
    return streetName
}
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  • \$\begingroup\$ I don't use mongo, but this doesn't look like it would even work. You modify streetName with an asynchronous callback, so you're returning the original empty String before the callback even has a chance to be called. e.g. stackoverflow.com/questions/57330766/… \$\endgroup\$
    – Tenfour04
    Oct 4, 2021 at 1:02

1 Answer 1

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This is how it would look in Java:

public String getStreetNameByStreetId(String id) {
    Query streetNameByStreetId = Query.query(
            Criteria.where("_id").is(id));
    byStreetId.fields().include("name");
    return mongoTemplate.find(streetNameByStreetId, Street.class)
          .get(0).getName();
}

I realize you are looking for how this would look in Kotlin, but it should look very similar. Also, for simple CRUD operations you might want to consider just using a MongoRepository and leveraging the Domain Specific Language (DSL).

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