Specify multiple criteria's in spring mongo db

Question

I am iterating over a list of key/value pairs and executing find for each key/value. Can I create a single query document to be kind of union in sql, So that there will be only one database call.

    List<User> userList = new ArrayList<User>();
    for (Map accounts:attributes) {
        Query query = new Query();
        List<Criteria> andCriteriaList = new ArrayList<Criteria>();
        accounts.forEach((key, value) -> {
            Criteria criteria = Criteria.where((String) key).is(value);
            andCriteriaList.add(criteria);
        });
        query.addCriteria(new Criteria().andOperator(andCriteriaList.toArray(new Criteria[andCriteriaList.size()])));
        if (mongoTemplate.exists(query, User.class)) {
            userList.add((User)mongoTemplate.find(query, User.class));
            //System.out.println(mongoTemplate.find(query, User.class));
        }

Thanks,

Answer 1

You can refactor your code to create $or expressions. No explicit $and operator needed.

Something like

 Query orQuery = new Query();
 Criteria orCriteria = new Criteria();
 List<Criteria> orExpression =  new ArrayList<>();
 for (Map<String, Object> accounts : attributes) {
   Criteria expression = new Criteria();
   accounts.forEach((key, value) -> expression.and(key).is(value));
   orExpression.add(expression);
 }
 orQuery.addCriteria(orCriteria.orOperator(orExpression.toArray(new Criteria[orExpression.size()])));
 List<User> userList = mongoOperations.find(orQuery, User.class);

This should output query like

{ "$or" : [{ "key1" : "value1", "key2" : "value2" }, { "key3" : "value3", "key4" : "value4" }] }