Im trying to read a (mongo)userdatabase with java. On the tutorial page I saw how to read the whole collection. I can do something like that:
DBCursor cursor = col.find();
while (cursor.hasNext()) {
System.out.println(cursor.next());
}
Now if I have a collection with users := name, age, password (...) and whatever. Now I would like to find a name with a password. For example for a login process. Lets say I have two strings: String n and p. If there is a user.equals(n) and a password.equals(p) in the database then login user. How do I have to change my cursor? I saw some query examples on the mongodb java tutorial page, but duh I really dont get it...
Any ideas? Thank you
Awesome, you'll love Mongo.
In the example you posted, the program iterates through a set of results. In the user/password problem you describe what you are actually trying to do is get one document (not a set of documents) based on some criteria.
On the shell that would look like this:
n = "login"
p = "password"
db.users.findOne({ user: n, password: p})
Notice I'm using findOne instead of find which returns a document instead of a cursor to many documents.
Now, lets take a look at the java driver's example:
BasicDBObject query = new BasicDBObject();
query.put("i", 71);
cur = coll.find(query);
while(cur.hasNext()) {
System.out.println(cur.next());
}
The BasicDBObject creates the query object and then you put different criteria which together form your query.
So instead of query.put("i", 71);
you would do something like:
query.put("user", n)
query.put("password", p)
and... instead of the while loop just use findOne instead of find so you don't have to iterate over the result set of 1 object (pointless).
You can read more about findOne() here.
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