In Jongo, how to find multiple documents from Mong

问题:

In mongodb, I can do this by the following query:

find(
    { _id : { $in : [ ObjectId('5275c6721a88939923c3ea54'), ObjectId('5275c6721a88939923c3ea55'), ObjectId('5275c6721a88939923c3ea56'), ObjectId('5275c6721a88939923c3ea57'), ObjectId('5275c6721a88939923c3ea58') ] } }
)

But how can we do the same using Jongo code?

I know we can find one document via:

db.getCollection("mongoEg").findOne(Oid.withOid("5194d46bdda2de09c656b64b")).as(MongoTest.class);

But how to get more than one documents in one query via Jongo?

回答1:

I see two options to achieve a find on multiple ids:

// 1. find with an array of ids
ObjectId[] ids = {id, id, id};
collection.find("{_id:{$in:#}}", ids).as(Friend.class);

// 2.find a list of ids
collection.find("{_id:{$in:[#, #, #]}}", id, id, id).as(Friend.class);

findOne offers a convenience method with an ObjectId and, if you use an annotated String instead of an ObjectId, the Oid.withOid method transforms your String into an ObjectId.

But, in the end, this convenience method input is transformed into a regular stringified query. So if the convenience don't fit your need, try a query instead.