Spring MongoDB getting only values instead of key:value in result-CodePudding

Hello so I am trying to get list of IDs from mongoDB , wrote this code that returns map of id:value I just want it to return just values .

        query=new Query(Criteria.where("_id").is("47b3b1ab-2d80-42cf-b289-e3d45497b59f"));
        query.fields().include("recordList.id").exclude("_id");
        System.out.println( mongoTemplate.findOne(query, Map.class,"Company3"));

{recordList=[{id=rec4vCGPy3EnXRuCM}, {id=recAivYlqtDzZP62C}, {id=recbcLfxuLLB6Jjn0}, {id=reckIA8RdQtDUKCYI}, {id=rectnZZzBJ2iKN8eO}]}

But I need something like this

[rec4vCGPy3EnXRuCM, recAivYlqtDzZP62C, recbcLfxuLLB6Jjn0, reckIA8RdQtDUKCYI, rectnZZzBJ2iKN8eO]

Yes I know I can manipulate result like this to get desired result but I want to know if its possible to achieve same result directly from DB and not like this

        List<Map<String,String>> list = (List<Map<String, String>>) mongoTemplate.findOne(query, Map.class,"Company3").get("recordList");

        List<String> idList=new ArrayList<>();
        for (Map<String, String> stringStringMap : list) {
            idList.add(stringStringMap.get("id"));
        }

This is what my data looks like mongodb document. Sorry for inserting image , couldnt copy it without it being unreadable .

CodePudding user response：

Maybe distinct could help. https://docs.mongodb.com/manual/reference/method/db.collection.distinct/

Query query=new Query(Criteria.where("_id").is("adfe377d-6e5b-48f0-b5bb-12b09f57285d"));

System.out.println(mongoTemplate.findDistinct(query,"recordList.id","Company4",String.class));

CodePudding user response：

You can not do that using Mongodb. This database is document oriented, meaning that given a criteria (in this case, an id), you will get a list of documents satifying the criteria where each document has some properties and some values.

To make it easier, you could rewrite your code so you could map your result to a pojo which only contains the list of ids you want and no key.

It would be something similar to the following:

public class Result {

private List<String> ids;

// getters and setters here

@override
public String toString(){
    return ids.toString();
}

}

Now your repository method retrieving data will look like the following:

query = new Query(Criteria.where("_id").is("47b3b1ab-2d80-42cf-b289-e3d45497b59f"));

// No need for this //query.fields().include("recordList.id").exclude("_id");

System.out.println( mongoTemplate.findOne(query, Result.class,"Company3"));

CodePudding user response：

oblivion02's solution was a little bit wrong but definitely hinted me in right direction , thank you.

Query query=new Query(Criteria.where("_id").is("adfe377d-6e5b-48f0-b5bb-12b09f57285d"));
System.out.println(mongoTemplate.findDistinct(query,"recordList.id","Company4",String.class));

Just these two lines give me a nice clean list of just id values

[rec4vCGPy3EnXRuCM, recAivYlqtDzZP62C, recbcLfxuLLB6Jjn0, reckIA8RdQtDUKCYI]