Retrieve mongodb array element using java

Question

I have this in my db.

{
"_id" : ObjectId("59424f41baaacf1f40815ae8"),
"first_name" : "Yazid",
"last_name" : "Amir",
"gender" : "Male",
"hobby" : ["Memanah", "Business", "Fusal", "Makan"]
}

Let say that I want to retrieve the "Business" from array hobby. So my code will be like this

MongoCollection collection = db.getCollection("customers");
BasicDBObject whereQuery = new BasicDBObject();
whereQuery.put("first_name", "Yazid");

MongoCursor<Document> cursor = collection.find(whereQuery).iterator();

try {
while (cursor.hasNext()) {
    Document str = cursor.next();



    out.println(str.get("hobby.0")); // display specific field
}
} finally {
cursor.close();
}

However, the result is null.

Get the property which is actually "hobby" and then access the array like a normal Java List. MongoDB "Dot notation" does not apply to Java Objects. — Neil Lunn
– Neil Lunn, Commented Jun 16, 2017 at 3:20

Dat Huynh · Accepted Answer · 2017-06-16 03:20:38Z

3

Use a List<Document> to store your array

while (cursor.hasNext()) {
    Document str = cursor.next();

    List<Document> list = (List<Document>)str.get("hobby");

    out.println(list.get(0)); // display specific field
}

answered Jun 16, 2017 at 3:20

Dat Huynh

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1 Comment

Dat Huynh Over a year ago

Glad I could help :)

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