reference to an element in a list in mongodb

Question

I have a File and I want to get the Directory

My mongo table Directory is built this way:

0
   _id
   _class
   listOfFiles[2]
                -0
                      $ref       File
                      $id        idmongodb1   
                -1
                      $ref       File 
                      $id        idmongodb2 
1
   _id
   _class
   listOfFiles[1]
                -0
                      $ref       File
                      $id        idmongodb3

And I would like to know how to get the way to the idmongodb(1 or 2 or 3)

Can my query :

    Query query = new Query();
    query.addCriteria(
            new Criteria().andOperator(

            Criteria.where("listOfFiles.$id").is(new ObjectId(file.getId()))
            )

    );

    return  mongoTemplate.findOne(query,Directory.class);

work ?

I would like to have confirmations.

In my JavaCode, the corresponding class Directory is buid this way

  public class Directory{

       public List<File> listOfFiles;   

 }

Thanks

Smutje · Accepted Answer · 2014-02-14 10:05:52Z

1

Try $elemMatch (http://docs.mongodb.org/manual/reference/operator/query/elemMatch) for querying elements within a collection.

answered Feb 14, 2014 at 10:05

Smutje

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Comments

Makoto · Accepted Answer · 2014-02-17 08:21:16Z

0

The query

 Query query = new Query();
query.addCriteria(
        new Criteria().andOperator(

        Criteria.where("listOfFiles.$id").is(new ObjectId(file.getId()))
        )

);

return  mongoTemplate.findOne(query,Directory.class);

actually works

answered Feb 17, 2014 at 8:21

Makoto

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