Adding values to an Array in MongoDB with Java

Question

I have a document stored in a collection in a mongo database. I want to be able to add to two arrays that are already in the document.

Method for creating the document and arrays:

public void addNewListName(String listName) {

    MongoCollection<Document> collection = database.getCollection("lists");

    ArrayList< DBObject > array = new ArrayList< DBObject >();
    Document list = new Document ("name", listName)
            .append("terms", array)
            .append("definitions", array);
    collection.insertOne(list);
}

Method where I want to add values into the array:

public void addVocabToList(String listName, String newVocabTerm, String newDefinition) {

}

The picture shows what the document looks like in MongoDB Compass after the first method is executed

glytching · Accepted Answer · 2017-08-09 19:25:34Z

3

Your addVocabToList() implementation will look something like this:

MongoCollection<Document> collection = database.getCollection("lists");

Document updatedDocument = collection.findOneAndUpdate(
    Filters.eq("name", listName),
    new Document("$push",
        new BasicDBObject("terms", new BsonString(newVocabTerm))
            .append("definitions", new BsonString(newDefinition))),
        new FindOneAndUpdateOptions().returnDocument(ReturnDocument.AFTER));

That code will:

Find the document having name=listName
Append the value of newVocabTerm to the terms array
Append the the value of newDefinition to the definitions array
Return the updated document (this part is optional)

answered Aug 9, 2017 at 19:25

glytching

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1 Comment

KobiF Over a year ago

Works flawlessly. Thank you so much!

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