MongoDB equivalent of SQL expression '1=1' in Java

Question

In SQL you can do the following;

SELECT * FROM CUSTOMERS WHERE ID=43 AND 1=1

How can I feed boolean expressions like '1=1' or '4<6' as criteria to MongoDB logical operators in Java?

For instance, I can do;

collection.find("$or",Arrays.asList(new Document("field1",value1),new Document("field2",value2)))

however, the above criteria are always based on already existing fields, while what I would like to do instead is more something like this (won't compile);

collection.find("$and",Arrays.asList(new Document(1,1),new Document("field2",value2)))

The reason I need this, is because I have a list of '$or' criteria but this list might be empty - in this case I want to have no criteria at all.

---

Update 1

While @gil.fernandes's solution is great for find queries, it will not work in aggregation queries (which is also what I need);

AggregateIterable aggregationQuery = collection.aggregate(Arrays.asList(
    [...]
    new Document("$match", new Document("$or", Arrays.asList(new Document("$where","1==1"))))
));

MongoCommandException: Command failed with error 16395: '$where is not allowed inside of a $match aggregation expression'

Any ideas on how we can use the '1=1' logic in $match operators of aggregation?

Update 2

I applied @Veeram's second solution using mongo server version 3.4.7 However, if I include the addFields and match objects into my aggregation query I get 0 results. If I remove them, I get all the results.

collection = mongoClient.getDatabase("testDatabase").getCollection("testColletion");
collection.insertOne(new Document("testField","testValue"));
Bson addFields = Aggregates.addFields(new Field<>("cmp", new Document("$or", Arrays.asList(new Document("$eq", Arrays.asList(1, 1))))));
Bson match = Aggregates.match(Filters.eq("cmp", 1));
AggregateIterable aggregationQuery = collection.aggregate(Arrays.asList(
        new Document("$match", new Document("testField", "testValue")),
        addFields,
        match
));
boolean hasDocuments = aggregationQuery.iterator().hasNext()

Answer 1

You can $expr on 3.6 mongo server version.

import static com.mongodb.client.model.Aggregates.addFields;
import static com.mongodb.client.model.Aggregates.match;
import static com.mongodb.client.model.Filters.*;
import static java.util.Arrays.asList;

Something like

Bson match = match(expr(new Document("$or", asList(new Document("$eq", asList(1, 1))))));
AggregateIterable aggregationQuery = collection.aggregate(asList(
                [...]
                match
));

This should output query something like

{ "$match" : { "$expr" : { "$or" : [{ "$eq" : [1, 1] }] } } }

For lower version 3.4 you can use combination of $addFields and $match to achieve the similar query.

Bson addFields = addFields(new Field<>("cmp", new Document("$or", asList(new Document("$eq", asList(1, 1))))));
Bson match = match(eq("cmp", true));
AggregateIterable aggregationQuery = collection.aggregate(asList(
               [...]
               addFields,
               match
));

This should output query something like

{ "$addFields" : { "cmp" : { "$or" : [{ "$eq" : [1, 1] }] } } }    
{ "$match" : { "cmp" : true } }