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Morphia Mongodb searching an array of string

I was trying to write a query criteria using Morphis for something like:
db.Response.find( { $and: [ { fields: [ "NAME","EMAIL"]},{intent:"CHECKUSR" }] } )
Can you help me with this? The problem here is I need to check with a array called fields, and the above query in working in MongoDB, but not able to find a suitable option in morphia for this.
Any help will be appreciated.

Datastore ds = ...
Query<Record> q = ds.createQuery(Record.class);
q.and(
q.criteria("Intent").equal(CHECKUSR),
q.criteria("fields.email").equal(EMAIL)
);
//list
List<Record> entities = q.asList();
another approach would be
Query q = ds.createQuery(Record.class).field("fields").hasThisElement(email);
this basically is an example on how you can write your criteria. You can tweak it for your purpose.
in the above samples Record is a class representing your document

Spring Data Mongo - Query methods and Distinct field

I'm currently working on a project using Spring Data Mongo.
My repository is just an interface extending MongoRepository. I would like to add a custom query method in order to retrieve all distinct values for one of my collection's fields.
I tried something like this:
#RepositoryRestResource(path = "devices", collectionResourceRel = "deviceInfos")
public interface DeviceInfoRepository extends MongoRepository<DeviceInfo, String> {
#RestResource(path = "distinctUnitIds")
List<String> findDistinctUnitIdBy();
}
With that code, Spring give me an error because it's not able to build my list. So I tried this:
#RepositoryRestResource(path = "devices", collectionResourceRel = "deviceInfos")
public interface DeviceInfoRepository extends MongoRepository<DeviceInfo, String> {
#RestResource(path = "distinctUnitIds")
List<DeviceInfo> findDistinctUnitIdBy();
}
That code works but the distinct seems to be totally ignored.
The documentation about Distinct in query method is really not clear...
Did I do something wrong? What's the best way to solve get the distinct values of a field using Spring Data?
Thanks!

You will have to use Spring Data MongoTemplate - the MongoRepository interfaces are made only for basic functionality and for more fine grain control of what you are querying, its best to use MongoTemplate.
Here is an example of how one would get distinct values from a collection:
Criteria criteria = new Criteria();
criteria.where("dataset").is("d1");
Query query = new Query();
query.addCriteria(criteria);
List list = mongoTemplate.getCollection("collectionName")
.distinct("source",query.getQueryObject());
Here is the link to more info: mongodb mongoTemplate get distinct field with some criteria

in SpringBoot2 you can do the following :
DistinctIterable<String> iterable = mongoTemplate.getCollection(COLLECTION_NAME).distinct("source",in(FieldValue,query.getQueryObject(), String.class);
MongoCursor<String> cursor = iterable.iterator();
List<String> list = new ArrayList<>();
while (cursor.hasNext()) {
list.add(cursor.next());
}
return list;

Getting count and list of ids using ElasticsearchTemplate in spring-data-elasticsearch

I am using spring-data-elasticsearch for a project to provide it with full text search functionality. We keep the real data in a relational database and relevant metadata along with respective id in elasticsearch. So for search results, only id field is required as the actual data will be retrieved from the relational database.
I am building the search query based on search criteria and then performing a queryForIds():
SearchQuery searchQuery = new NativeSearchQueryBuilder()
.withIndices(indexName)
.withTypes(typeName)
.withQuery(getQueryBuilder(searchParams))
.withPageable(pageable)
.build();
return elasticsearchTemplate.queryForIds(searchQuery);
If I also need the total count for that specific searchQuery, I can do another elasticsearchTemplate.count(searchQuery) call, but that will be redundant as I understand. I think there is a way to get both the list of id and total count by using something like elasticsearchTemplate.queryForPage() in a single call.
Also, can I use a custom class in queryForPage(SearchQuery query, Class<T> clazz, SearchResultMapper mapper) which is not annotated with #Document? The actual document class is really big, and if I am not sure if passing large classes will cause any extra load on the engine since there are over 100 fields to be json mapped, but all I need is the id field. I will have a .withFields("id") in the query builder anyway.

If you want to prevent two calls to elasticsearch, i would suggest to write an custom ResultsExtractor:
SearchQuery searchQuery = new NativeSearchQueryBuilder().withIndices(indexName)
.withTypes(typeName)
.withQuery(queryBuilder)
.withPageable(pageable)
.build();
SearchResult result = template.query(searchQuery, new ResultsExtractor<SearchResult>() {
#Override
public SearchResult extract(SearchResponse response) {
long totalHits = response.getHits()
.totalHits();
List<String> ids = new ArrayList<String>();
for (SearchHit hit : response.getHits()) {
if (hit != null) {
ids.add(hit.getId());
}
}
return new SearchResult(ids, totalHits);
}
});
System.out.println(result.getIds());
System.out.println(result.getCount());
where SearchResult is a custom class:
public class SearchResult {
List<String> ids;
long count;
//getter and setter
}
This way you can get the information you need from the elasticsearch SearchResponse.
Regarding your second question: As far as I can see, when calling queryForPage(SearchQuery query, Class<T> clazz, SearchResultMapper mapper)
the passed class is not checked for the #Document annotation. Just try it out!

One may also consider using AggregatedPage<T>. You can get the total number of records, total pages, current page records, etc. just like in Pageable<T>.
SearchQuery searchQuery = new NativeSearchQueryBuilder().withIndices(indexName)
.withTypes(typeName)
.withQuery(queryBuilder)
.withPageable(pageable)
.build();
AggregatedPage<ElasticDTO> queryResult = elasticsearchTemplate.queryForPage(searchQuery , ElasticDTO.class);

Morphia to return List of strings which are the fields of all documents

If I got a collection full of following elements
#Entity
public void MyEntity{
public String name;
public String type;
...
}
And I want to return a List<String> (or Set) of not the elements, but only their name fields.
List<String> allNames = datasotre.find(MyEntity.class).asList("name");
This is sample query, there is no such method of Morphia datastore.

To limit the fields returned call the "retrievedFields" method on Query. For example, to only get the name field of all MyEntity objects:
datastore.find(MyEntity.class).retrievedFields( true, "name").asList()
Edit - You can get a list Strings using the following query as long as you don't mind that the list will only contain unique values (i.e. no duplicate names):
DBCollection m = datastore.getCollection( MyEntity.class );
List names = m.distinct( "name", new BasicDBObject() );
The "names" list will only contain Strings.

The problem here is that there is no actual query for "keys". The queries all return "key/value pairs".
In theory, the fields in datastore.find() should map to the fields in MyEntity so you could just use reflection. However, if you have other people writing to the DB from different places they may have seeded extra tables.
If this is the case, you will need to run a Map/Reduce to get the list of all the "key" names.
There is a sample here.

You are looking for datastore.find(MyEntity.class).retrievedFields(true, "name").asList();. This will contain the _id and name attribute.
See http://code.google.com/p/morphia/wiki/Query#Ignoring_Fields

Retrieve sub-document in array as DBObject(s)

I'm very new to MongoDB, and I'm using it along with the Java driver. I have this document structure:
{ "_id" : ObjectId("4f7d2ba6fd5a306d82687d48"), "room" : "Den" }
{ "_id" : ObjectId("4f7d2baafd5a306d82687d49"), "room" : "Foyer" }
{ "_id" : ObjectId("4f7d2fdcfd5a306d82687d4a"), "room" : "Master Bedroom" }
{ "_id" : ObjectId("4f7d301afd5a306d82687d4b"), "room" : "Guest Bedroom" }
{ "_id" : ObjectId("4f7d2b98fd5a306d82687d47"), "code" : "A", "lights" : [ { "name" : "Overhead", "code" : "1" } ], "room" : "Kitchen" }
Where the last line is of particular interest in illustrating what I want to do. Each document is a room and may have a "lights" key corresponding to a value that is an array of sub-documents. From a modeling perspective, I have a house, which has 0-n rooms, each of which has 0-n lights in it. What I want to do in Java is take the name of the room as a parameter, and return a collection of DBObject corresponding to the sub-documents in the lights array -- "get me all lights for room 'kitchen'", for example.
So far, proceeding incrementally in TDD style, I've constructed this query:
public static final String ROOM_KEY = "room";
public static final String EQUALS_KEY = "$eq";
private BasicDBObject buildRoomNameQuery(String roomName) {
BasicDBObject myQuery = new BasicDBObject();
myQuery.put(ROOM_KEY, new BasicDBObject(EQUALS_KEY, roomName));
return myQuery;
}
I realize that this is going to get me the entire room document for the room name I pass in. I'm a bit stuck on what the best way to proceed from here is to get what I want. Is what I'm doing even possible with a simple query, or will I have to retrieve the array and iterate through it in code, casting the elements as DBObject? I'm also open to suggestions for a better document structure for my purpose -- I'm not married to this structure by any means.
For a bit of perspective, I'm quite well versed in SQL and traditional relational databases, if that helps in terms of explanatory analogies. Also, if I'm butchering the MongoDB terminology, please correct me. Thanks in advance.

So, you can do something like this:
DBCollection coll = db.getCollection("test");
BasicDBObject query = new BasicDBObject("room", "Kitchen");
// optional, limit the fields to only have the lights field
BasicDBObject fields = new BasicDBObject("lights",1).append("_id",false);
DBCursor curs = coll.find(query, fields);
while(curs.hasNext()) {
DBObject o = curs.next();
// shows the whole result document
System.out.println(o.toString());
BasicDBList lights = (BasicDBList) o.get("lights");
// shows the lights array -- this is actually a collection of DBObjects
System.out.println(lights.toString());
// optional: break it into a native java array
BasicDBObject[] lightArr = lights.toArray(new BasicDBObject[0]);
for(BasicDBObject dbObj : lightArr) {
// shows each item from the lights array
System.out.println(dbObj);
}
}
Also, I recommend using the QueryBuilder in the Java driver--it's a bit more concise than creating Queries from DBObjects. Even better, check out Morphia, which is an object mapper that uses the Java driver. It natively supports entity models that have lists in them, and serializes/deserializes them to Mongo without needing to deal with the DBObject stuff.

Look at spring mongo package. A really good way to work with mongo using POJO documents
http://www.springsource.org/spring-data/mongodb
You will not need to perform casting and work with strings

You can use an iterator for the fields
Iterator<DBObject> fields = curs.iterator();
while(fields.hasNext()){
DBObject field = (DBObject) fields.next().get("lights");
System.out.println(field.get("name"));
}

For newer versions, consider the use of the Document. To avoid unchecked casts and linter warnings, along with writing your own loop, use the libary's get(final Object key, final Class<T> clazz) method:
List<Document> comments = posts.get("comments", docClazz)
where docClazz is something that you create once:
final static Class<? extends List> docClazz = new ArrayList<Document().getClass();