SpringData + Protobuf + Mongodb magic @ID handler

[pauldavidgilligan]

Hi,

I was testing storage of a Google Protobuf document into mongodb and decided for simplicity to use "." dot notation for the "_id" field in the database.

So the "_id" entry would be made from 3 fields from the protobuf as follows:

"_id" : "3936303865666539656633653461333362373536363664363534353766363831.517f7dfb.PDG*"

message Message {

    message Identity {
        required string group = 1; // 32 chars
        required string epoch = 2; // 4 hex chars
        required string sender = 3; // 3 chars 
    }
    required Identity identity = 1; // 39 char   

    required string state = 2; // 1 char

    message Signal { // 64 chars
  ... etc
    }
    required Signal signal = 3;   
}

I implemented a MessageReadConverter & MessageWriteConverter for the spring data Converter all works great.

My questions is what part of the architect managed to convert the "." fields during reading the mongodb data into the correct Identity part of my protobuf object ?

The writer is:

    @Override
    public DBObject convert(Lwwk.Message msg) {
        final DBObject dbo = new BasicDBObject();        
        final String jsonSignal = JsonFormat.printToString(msg.getSignal());               
        dbo.put("_id", Elements.toIdentityString(msg.getIdentity()));
        dbo.put("state", msg.getState());
        
        // TODO: this seems so wrong but it works
        dbo.putAll((BSONObject) JSON.parse(jsonSignal)); // capture sub docs
        return dbo;
    }

and the reader:

    @Override
    public Message convert(DBObject o) {        
        // TODO: it works out the delimited ID itself ?
        return composer.buildPartial();
    }

and a correctly built protobuf object is populated:

2539 [main] INFO net.lwwk.services.core.BlackBox - GOT 
identity {
  group: "6136653462636639323363393464656439343933306130393939323135656563"
  epoch: "517f8088"
  sender: "PDG*"
}
state: "?"
signal {
...etc
}

[pauldavidgilligan]

If I comment out the reader in the spring config no longer works.