RavenDB query returns null

Question

I'm on RavenDB 3.5.35183. I have a type:

import com.mysema.query.annotations.QueryEntity; @QueryEntity public class CountryLayerCount { public String countryName; public int layerCount; }

and the following query:

private int getCountryLayerCount(String countryName, IDocumentSession currentSession) { QCountryLayerCount countryLayerCountSurrogate = QCountryLayerCount.countryLayerCount; IRavenQueryable<CountryLayerCount> levelDepthQuery = currentSession.query(CountryLayerCount.class, "CountryLayerCount/ByName").where(countryLayerCountSurrogate.countryName.eq(countryName)); CountryLayerCount countryLayerCount = new CountryLayerCount(); try (CloseableIterator<StreamResult<CountryLayerCount>> results = currentSession.advanced().stream(levelDepthQuery)) { while(results.hasNext()) { StreamResult<CountryLayerCount> srclc = results.next(); System.out.println(srclc.getKey()); CountryLayerCount clc = srclc.getDocument(); countryLayerCount = clc; break; } } catch(Exception e) { } return countryLayerCount.layerCount; }

The query executes successfully, and shows the correct ID for the document I'm retrieving (e.g. "CountryLayerCount/123"), but its data members are both null. The where clause also works fine, the country name is used to retrieve individual countries. This is so simple, but I can't see where I've gone wrong. The StreamResult contains the correct key, but getDocument() doesn't work - or, rather, it doesn't contain an object. The collection has string IDs.

In the db logger, I can see the request coming in:

Receive Request # 29: GET - geodata - http://localhost:8888/databases/geodata/streams/query/CountryLayerCount/ByName?&query=CountryName:Germany Request # 29: GET - 22 ms - geodata - 200 - http://localhost:8888/databases/geodata/streams/query/CountryLayerCount/ByName?&query=CountryName:Germany

which, when plugged into the browser, correctly gives me:

{"Results":[{"countryName":"Germany","layerCount":5,"@metadata":{"Raven-Entity-Name":"CountryLayerCounts","Raven-Clr-Type":"DbUtilityFunctions.CountryLayerCount, DbUtilityFunctions","@id":"CountryLayerCounts/212","Temp-Index-Score":0.0,"Last-Modified":"2018-02-03T09:41:36.3165473Z","Raven-Last-Modified":"2018-02-03T09:41:36.3165473","@etag":"01000000-0000-008B-0000-0000000000D7","SerializedSizeOnDisk":164}} ]}

The index definition:

from country in docs.CountryLayerCounts select new { CountryName = country.countryName }

AFAIK, one doesn't have to index all the fields of the object to retrieve it in its entirety, right ? In other words, I just need to index the field(s) to find the object, not all the fields I want to retrieve; at least that was my understanding...

Thanks !

What does CountryLayerCount/ByName looks like?

Ayende Rahien
– Ayende Rahien

2018-02-03 21:50:03 +00:00
Commented Feb 3, 2018 at 21:50 — Ayende Rahien
– Ayende Rahien, Commented Feb 3, 2018 at 21:50
@Ayende: updated the question

Hiro Protagonist
– Hiro Protagonist

2018-02-04 16:27:07 +00:00
Commented Feb 4, 2018 at 16:27 — Hiro Protagonist
– Hiro Protagonist, Commented Feb 4, 2018 at 16:27

Marcin · Accepted Answer · 2018-02-05 09:17:03Z

The problem is related to incorrect casing.

For example:

try (IDocumentSession sesion = store.openSession()) { CountryLayerCount c1 = new CountryLayerCount(); c1.layerCount = 5; c1.countryName = "Germany"; sesion.store(c1); sesion.saveChanges(); }

Is saved as:

{ "LayerCount": 5, "CountryName": "Germany" }

Please notice we use upper case letters in json for property names (this only applies to 3.X versions).

So in order to make it work, please update json properties names + edit your index:

from country in docs.CountryLayerCounts select new { CountryName = country.CountryName }

Btw. If you have per country aggregation, then you can simply query using:

QCountryLayerCount countryLayerCountSurrogate = QCountryLayerCount.countryLayerCount; CountryLayerCount levelDepthQuery = currentSession .query(CountryLayerCount.class, "CountryLayerCount/ByName") .where(countryLayerCountSurrogate.countryName.eq(countryName)) .single();

thank you for a detailed, yet concise and very useful answer. The culpability is probably mine for not reading the documentation properly and relying on assumptions...

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