Java equivalent for a MongoDB select query

Question

I would like to retrieve the following information:

select names from database where names like 'Jon';

but for MongoDB in Java. Essentially, it should return all names that contain the word Jon in them, like Jonathan, Jong etc etc. I know that there is the $in operator in MongoDB, but how do I do the same in Java, using the Java driver? I've been trying to look for it everywhere but am getting nothing. I've tried: query = new BasicDBObject("names", new BasicDBObject("$in", "Jon"));, and query = new BasicDBObject("names", new BasicDBObject("$in", Jon));

But neither of them worked :( Please help!

@dadu: I did, but there's nothing for my specific query. I tried query = new BasicDBObject("names", new BasicDBObject("$in", "Jon"));, and query = new BasicDBObject("names", new BasicDBObject("$in", Jon)); But neither of them worked :( I did look up Morphia too, but I'm kinda crunching on time, and implementing that is kinda beyond my time frame, especially since I only need one single query. — CodingInCircles
– CodingInCircles, Commented Dec 4, 2012 at 21:42
@AaronKurtzhals: Please refer my comment now. I realised I hadn't posted my code. — CodingInCircles
– CodingInCircles, Commented Dec 4, 2012 at 21:42
That SQL query won't do what you say it does. To get everything where the name includes the string "Jon", you would use LIKE "%Jon%". To get only those which start with Jon, you would use LIKE "Jon%". The MongoDB $in operator is for searching in array fields. To search for string fragments, you can use $regex and regular expressions. — Philipp
– Philipp, Commented Dec 4, 2012 at 21:55

Philipp · Accepted Answer · 2012-12-04 22:01:06Z

10

The MongoDB Java driver equivalent of that SELECT statement would be:

BasicDBObject fields = new BasicDBObject().append("name", 1); // SELECT name
BasicDBObject query = new BasicDBObject().append("name", "Jon"); // WHERE name = "Jon"
DBCursor results = yourCollection.find(query, fields); // FROM yourCollection

When you want to search for a part of a string, you can use the $regex operator:

query = new BasicDBObject("name", new BasicDBObject("$regex", "Jon"));

This will get you all objects where the name matches the regular expression Jon, which is everything which includes the string "Jon" anywhere.

edited Dec 4, 2012 at 22:01

answered Dec 4, 2012 at 21:49

Philipp

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3 Comments

CodingInCircles Over a year ago

Yes, that's what I was looking for, my query was more like pseudocode, rather than actual code :P Can you please edit your answer accordingly? Thanks! :)

Philipp Over a year ago

I edited my answer and added the equivalent to a LIKE "%Jon%" query.

CodingInCircles Over a year ago

Please look at my new question: stackoverflow.com/questions/13732735/… and please see if you can lend your expertise in any way. Thanks! :)

George D · Accepted Answer · 2012-12-04 21:38:43Z

1

Check the Mongo-Java official site, plus a nice library for mapping mongo objects

answered Dec 4, 2012 at 21:38

George D

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Comments

Alexey Malev · Accepted Answer · 2014-05-06 14:07:34Z

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The $in operator in MongoDB resembles the IN operator in SQL. For instance, it can be used for executing SQL-like queries as

SELECT * FROM table WHERE id IN {1, 4, 6, 7, 9}

This is why it doesn't work for you. Use Regular expressions, as the others have already suggested.

edited May 6, 2014 at 14:07

Alexey Malev

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answered May 6, 2014 at 13:50

pkran

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