MongoDB: Distinct Categories within Posts Collection

[thoughtAddict]

Did a google search and found a lot of non-Mongo responses. (Try explaining that sentence to someone in the 80's). Found this forum and can't find a definitive answer.

Can we use "distinct" in the current spring data document API?

Ie. I have a "posts" collection with entries similar to:

{
"_id" : ObjectId("4df02289cafacff33d560a2c"),
"content" : "9 Lorem ipsum dolor sit amet, Excepteur sint occaecat cupidatat
non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
"dateCreated" : "06/08/2011 18:31 PM",
"author" : "Tom Foolery",
"categories" : [ "News of the 1800's", "Technology" ],
"title" : "Review: 'uz200v2a758k' JS library.",
"postId" : "f9be8697-dfc3-4a10-8965-5192e630ed09"
}

Trying to find all distinct "categories" entries, like:

db.posts.distinct("categories");


Thanks.

[thoughtAddict]

No? No one knows if this can be done, or should I provide a better explanation?

Just looking for a way to get a distinct listing of a particular attribute. I know how to do this using Mongo syntax, but am trying to find an equivalent within the Spring Data world.

Thanks.

[jwalker]

No? No one knows if this can be done, or should I provide a better explanation?

Just looking for a way to get a distinct listing of a particular attribute. I know how to do this using Mongo syntax, but am trying to find an equivalent within the Spring Data world.

Thanks.

One way that I've been able to get a distinct listing is to use the MongoOperations.getCollection(<collectionName>) to get the DBCollection object and then use DBCollection.distinct(<key>)

For example:

We have a Collection UserLogin with:
{
username;
timestamp;
}

and you want to get the distinct user names in the UserLogin collection via spring data, you could use:

MongoOperations mongoOps = mongoTemplate;
DBCollection userLoginCollection = mongoOps.getCollection("UserLogin");
List distinctUserNames = userLoginCollection.distinct("username");

Hope this helps.

[Samarth Bhargava]

Was looking for the same thing. Couldn't find direct Spring Data support, but you can always use the Java Driver methods directly by getting the DBCollection from the mongoTemplate:
DBCollection coll = mongoTemplate.getCollection("storeDetails");
List<String> res = coll.distinct("zipCode");