Add ability to perform update-with-replace for entire domain object by query [DATAMONGO-198]

[spring-projects-issues]

Sergey Alaev opened DATAMONGO-198 and commented

Currently there is no way to update (overwrite) entire object by query which is very useful for optimistic locking and already provided by mongo java driver. There are two possibilities:

• Get user a way to create Update from domain object
• Add new method(s) to MongoOperations like update(Query, Object) - not sure how it will fit into existing update(Query, Update) scheme.

Currently i'm forced to use code like

DBObject object = new BasicDBObject();
mongoTemplate.getConverter().write(project, object);
DBCollection collection = mongoTemplate.getCollection("myCollection");
WriteResult result = collection.update(query, object, WriteConcern.SAFE);

---

Affects: 1.0 M3

5 votes, 6 watchers

[spring-projects-issues]

Sergey Alaev commented

Since i cant edit created ticket - it is of course about MongoTemplate

[spring-projects-issues]

Mark Pollack commented

Isn't this functionality handled by updateMulti in MongoOperations. What is the API usage you are referring to in the mongodb driver

[spring-projects-issues]

Sergey Alaev commented

Unfortunately not - Update class allows only to update certain fields while i do need to overwrite an object without leaving any previous data.

API example is just above - collection.update(query, object, WriteConcern.SAFE);

[spring-projects-issues]

Sergey Alaev commented

Oh, found good link:
http://www.mongodb.org/display/DOCS/Atomic+Operations#AtomicOperations-%22UpdateifCurrent%22

For example, if we have
class Something {
private long version;
}

And going to update it with following pseudocode:

do {
Something s = loadLastVersion()
alterSomething(s);
} while (save("where s.version == " + version", s) != 1)

How can you express that in MongoTemplate API?

[spring-projects-issues]

Sergey Alaev commented

I cant find edit button so im correcting myself here:

do { 
  Something s = loadLastVersion();
  alterSomething(s);
  long prevVersion = s.version++; 
} while (saveOne("where s.version == " + prevVersion, s) != 1)

[spring-projects-issues]

Patrik Fredriksson commented

This would be a really nice addition. I extended Update and overrode getUpdateObject() to handle this case when implementing optimistic locking. Please make this functionality part of the API as suggested by original reporter above

[spring-projects-issues]

Abhinav Shah commented

Patrik,
Can you share your source code for getUpdateObject() ?

[spring-projects-issues]

Patrik Fredriksson commented

Sure. Note though that this was only used to spike optimistic locking support, and never went into production. Since support for optimistic locking is now built in, we use that instead. The code can most likely be improved.

import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import org.springframework.data.mongodb.core.convert.MongoConverter;
import org.springframework.data.mongodb.core.convert.MongoWriter;
import org.springframework.data.mongodb.core.query.Update;

public class MyUpdate extends Update {

   private MongoWriter converter;
   Object object;

   public MyUpdate(MongoConverter converter, Object object) {
      this.converter = converter;
      this.object = object;
   }

   @Override
   public DBObject getUpdateObject() {

      BasicDBObject obj = new BasicDBObject();
      converter.write(object, obj);
      return obj;
   }
}

[spring-projects-issues]

bodrin commented

+1 This is very basic functionality - optimistic locking / strong consistency was the reason I have chosen MongoDb and I can't believe that one cannot update whole objects/docs based on versioning (at least not straightforward through the API).
Please add this!

[spring-projects-issues]

Oliver Drotbohm commented

What does your scenario look like exactly? This ticket got side tracked by the whole optimistic locking story which has been released with 1.1.0.RELEASE already. This one here is actually tracking converting a domain object into an Update instance. Unfortunately this is not as straight forward as it seems as the ideas presented so far have completely ignored the aspect of defining whether a null in a domain object property means "should not be set during the update" or "should be set to null" or "field should be removed entirely" (see the Mongo docs for details. In general, Spring Data MongoDB does not prevent you from using the plain MongoDB driver API. You can do so by using the callbacks that can be handed to the execute(…) methods of MongoTemplate.

Still I'd like to hear details about your specific use case to possibly incorporate it into the fix for this ticket

[spring-projects-issues]

bodrin commented

Hi Oliver,

My use case is:

1. read an object of version X
2. perform some changes in it
3. repositoy.update(object, X) // updates/replaces the given object if the version matches otherwise throws OptimisticLockingException or returns false/whatever

I can't find how to do that into the docs and I have found this page and I'm using the Patrik's workaround from above.

Thanks!

[spring-projects-issues]

Oliver Drotbohm commented

That's exactly the way the MongoTemplate.save(…) method works internally since 1.1.0 when you use @Version in your domain classes. Thus the repositories benefit transparently from that behavior

[spring-projects-issues]

bodrin commented

I see, thank you! I cannot find @Version into the documentation at all ..

Note that sometimes I want to have version increasing with more then 1 (e.g. If I want to have event sourcing/CQRS and emit more then a single event into an update operation) so I guess I should again use the workaround or have double versions - "@Version long infrastructureVersion;" and "long version;" .. It would be nicer to have the expected version specified into the save method - save(object, expectedVersion) ..

Offtopic: why double insert does not throw exception - it just ignores me silently?

[spring-projects-issues]

Mark Paluch commented

Find and replace is available since 2.1 with findAndReplace