I'm trying to query a collection using operands AND'd together. I've got the shell version working:
db.widgets.find({color: 'black, shape: 'round', weight: 100})
I'm unable to find the Java equivalent (using the native driver). I've tried various things, but here is my latest attempt:
// Find all black, round widgets with weight 100
List<BasicDBObject> criteria = new ArrayList<BasicDBObject>();
criteria.add(new BasicDBObject("color", "black"));
criteria.add(new BasicDBObject("shape", "round"));
criteria.add(new BasicDBObject("weight", 100));
DBCursor cur = widgets.find(new BasicDBObject("$and", criteria));
// Get all matching widgets and put them into a list
List<Widget> widgetList = new ArrayList<Widget>();
DBCursor cur = widgets.find(andQuery);
while (cur.hasNext()) {
widgetList.add(new Widget(cur.next()));
}
if (widgetList.isEmpty())
System.out.println("No results found");
Any ideas what is wrong?
BasicDBObject criteria = new BasicDBObject();
criteria.append("color", "black");
criteria.append("shape", "round");
criteria.append("weight", 100);
DBCursor cur = widgets.find(criteria);
Another way to solve same problem is using aggregation:
// To print results
Block<Document> printBlock = new Block<Document>() {
@Override
public void apply(final Document document) {
System.out.println(document.toJson());
}
};
// get db connection and collection
MongoDatabase db= mongoClient.getDatabase("dbname");
MongoCollection<Document> collection= database.getCollection("collectionname");
collection.aggregate(Arrays.asList(Aggregates.match(Filters.eq("key1", "value1")),
Aggregates.match(Filters.eq("key2", "value2")),
Aggregates.match(Filters.eq("key3", "value3")))).forEach(printBlock);
For more details please refer the v 3.4 mongo Aggregation documentation.
http://mongodb.github.io/mongo-java-driver/3.4/driver/tutorials/aggregation/
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