Can I use String as ID type for mongodb document?

Question

I am using java/morphia to deal with mongodb. The default ObjectId is not very convenient to use from Java layer. I would like to make it a String type while keep the key genera

Answer 1

You can use a string as an ID from Java too. Here is an example method and corresponding Unit test inserting one object with a string ID in a MongoDB collection:

public Document insert(String json, String collectionName) {
    MongoCollection collection = database.getCollection(collectionName);
    BasicDBObject document = BasicDBObject.parse(json);
    Document doc = new Document(document);
    collection.insertOne(doc);
    return doc;
}

@Test
void whenInsert_ShouldInsertOne() {
    final String uuid = UUID.randomUUID().toString();
    final String collection = "test_collection";
    final Document doc = app.insert(String.format("{\"_id\":\"%s\", \"name\": \"test\"}", 
        uuid), collection);
    assertThat(doc).isNotNull();
    final String json = app.getById(uuid, collection);
    assertThat(json).contains(String.format("\"_id\": \"%s\"", uuid));
}