setting field to undefined then saving it causes ER_EMPTY_QUERY

[sjlu]

Using Sequelize 2.0.4

At the moment, when I change a field by nulling it out, it will clear out that field appropriately. An example of this is:

User.find(id).then(function(user){
 user.firstname = null;
 return user.save();
});

On the other hand, when I undefine it, for example:

user.firstname = undefined;
user.save()

It will throw me SequelizeDatabaseError: ER_EMPTY_QUERY: Query was empty since it is the only field that has changed. Note that on my model I have timestamps: false.

Executing (default): 
{[SequelizeDatabaseError: ER_EMPTY_QUERY: Query was empty]
 name: 'SequelizeDatabaseError',
 message: 'ER_EMPTY_QUERY: Query was empty',
 parent: 
{[Error: ER_EMPTY_QUERY: Query was empty]
 code: 'ER_EMPTY_QUERY',
 errno: 1065,
 sqlState: '42000',
 index: 0,
 sql: '' },
 original: 
{[Error: ER_EMPTY_QUERY: Query was empty]
 code: 'ER_EMPTY_QUERY',
 errno: 1065,
 sqlState: '42000',
 index: 0,
 sql: '' },
 sql: '' }

Now when diving into the code a little bit more, I see that it is picking up that the field has changed when logging options on https://github.com/sequelize/sequelize/blob/master/lib/instance.js#L581

But when it hits Utils.mapValueFieldNames, the value has disappeared due to it interpreting the value as undefined and therefore not picking it up on https://github.com/sequelize/sequelize/blob/master/lib/utils.js#L230

I can understand that null has a philosophically different meaning than undefined where undefined in Sequelize means "don't touch this value", should it be treated as null in this case? I know that it kind of duplicates specifying which fields to save https://github.com/sequelize/sequelize/blob/master/lib/instance.js#L541

If yes, should the call end early by adding

if (!_.keys(values).length) return this;

Or no and should it interpret undefined as null?

[BridgeAR]

This is just as it should be. Setting something to undefined in javascript has a different meaning than setting it to null. If sequelize would check for undefined, it would have to include all fields that are not defined and insert null. That's not a desired behaviour. Escmascript 6 is going to implement defaults too and that would be even more confusing with setting something to null if the value is actually undefined (Example).

@mickhansen @janmeier please close this.

[sfakir]

Is there any way, how to catch setting a value to undefined on the model?
It is really hard to debug, without even knowing which model is the reason for the error.

[jayfresh]

Just a note on this that calling changed() on a model instance that has had a field to set undefined does return the field that was cleared. I feel it's a bit unexpected that that identified change does not go on to be saved