error in function create using scaffold with mongodb

i'm trying to create a scaffold application with mongodb, like this:

```
compound init project --db mongodb
cd project
npm install
compound g scaffold person name
```

then i create a new person at localhost:3000/people/new
when i save the person i get the following error:

```
../node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/connection/base.js:245
throw message;
^
TypeError: Cannot read property '0' of null
at /project/node_modules/jugglingdb-mongodb/lib/mongodb.js:122:37
at /project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/collection/core.js:102:73
at /project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/db.js:1129:7
at /project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/db.js:1843:9
at Server.Base._callHandler (/project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/connection/base.js:445:41)
at /project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/connection/server.js:468:18
at MongoReply.parseBody (/project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/responses/mongo_reply.js:68:5)
at null. (/project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/connection/server.js:426:20)
at EventEmitter.emit (events.js:95:17)
at null. (/project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:201:13)
at EventEmitter.emit (events.js:98:17)
at Socket. (/project/node_modules/jugglingdb-mongodb/node_modules/mongodb/lib/mongodb/connection/connection.js:422:22)
at Socket.EventEmitter.emit (events.js:95:17)
at Socket. (_stream_readable.js:746:14)
at Socket.EventEmitter.emit (events.js:92:17)
at emitReadable_ (_stream_readable.js:408:10)
at emitReadable (_stream_readable.js:404:5)
at readableAddChunk (_stream_readable.js:165:9)
at Socket.Readable.push (_stream_readable.js:127:10)
at TCP.onread (net.js:528:21)
```

in my database the person was saved, but with "id" null:

```
{
"_id" : ObjectId("534fc9cbc1bb90b475a6bd82"),
"name" : "teste",
"id" : null
}
```

I'm using mongodb 2.6.0, ubuntu 13.04 and jugglingdb 0.2.13

The error occurs in jugglingdb-mongodb at line 122, where it tries to access property '0' of null. The issue is that the scaffold saves a record with an 'id' field set to null. Start by examining the jugglingdb-mongodb adapter's create method and how it handles ID generation for MongoDB. Check the compound scaffold generation code to see how it sets up models with MongoDB. Look at the saved document structure and compare with expected schema. Run the scaffold steps locally to reproduce the error, then trace through the save flow.

Written by the indexing model from the issue text.