Undefined properties are set to null in Mongodb

[danivek]

Description

versions :
js-data: 3.0.0-rc.6
js-data-mongodb : 1.0.0-rc.1

Steps to reproduce

Here is my model schema :

{
  "type": "object",
  "properties": {
    "a": {
      "type": "string"
    },
    "b": {
      "type": "string"
    }
  },
  "required": ["a"],
  "additionalProperties": false
}

When i insert or update not all the properties of my model (example with only property "a" : {a: "a"}), the others properties are set to undefined by js-data. So the input props of methods create or update looks like :

{
  a: "a",
  b: undefined
}

The problem is that the Node.js mongodb driver, insert null in the database for all the undefined properties. So when you just want to update property "a", the previous value of property "b" is erase by a null value.

The workaround solution i found, is to remove all undefined properties of the object in methods beforeCreate and beforeUpdate on the adapter. But i think it could be made directly on insert or update methods.

// Workaround to avoid undefined values to be set to null in MongoDB
const adapter = new MongoDBAdapter({
  uri: config.MONGODB_URI,
  beforeUpdate(mapper, id, props) {
    const removeUndefined = (obj) => {
      Object.keys(obj).forEach(key =>
        (obj[key] && typeof obj[key] === 'object') && removeUndefined(obj[key]) ||
        (obj[key] === undefined) && delete obj[key]
      );
      return obj;
    };
    removeUndefined(props);
  }
});

Solution can be found here : http://stackoverflow.com/questions/286141/remove-blank-attributes-from-an-object-in-javascript. It should be recursive and only remove undefined properties.

Any thoughts ?

Thanks!

[crobinson42]

@jmdobry is this caused by the adapter or js-data v3 schema validation?

[jmdobry]

Interesting, I'll have to give it a try. If the MongoDB driver was sane, it would treat undefined as "property does not exist", instead of converting it to null.

[danivek]

@crobinson42, @jmdobry

I look at the MongoDB Driver documentation for DB class, there is an option that can be set to the DB instance ignoreUndefined. I don't know why it is set to false by default...

So an other possible solution that works is to set ignoreUndefined to true on connect method:

MongoClient.connect(opts.uri, {
      db: {
        ignoreUndefined: true
      }
    }, (err, db) => {
      if (err) {
        return reject(err)
      }
      this._db = db
      resolve(db)
    })

I will try to investigate further why this behavior is not the default one.

[danivek]

More infos found here : https://github.com/christkv/mongodb-core/issues/31, Automattic/mongoose#3169

[crobinson42]

@danivek thx for the leg work on the mongo driver opts!