Specify multiple criteria's in spring mongo db query - mongodb

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" }] }

Answer 2

if you want to query multiple fields(field1, field2, ....) with values below is the solution
Query query = new Query();
List<Criteria> criteria = new ArrayList<>();
criteria.add(Criteria.where(field1).is(field1val));
criteria.add(Criteria.where(field2).is(field2val));
// you can add all your fields here as above
query.addCriteria(new Criteria().andOperator(criteria.toArray(new Criteria[criteria.size()])));
List<JSONObject> filteredVals = mongoOperations.find(query, JSONObject.class);
the above return filteredVals is JSONObject