I'm trying to build some custom types to create reusable type/value checking within my API.

The problem I've got is that if there's a problem with the serialization, there's no way to silently ignore the value.

For example, in mysql, a non-null DATETIME that's ignored at insert time is assigned the value 0000-00-00 00:00:00.
The mysql2 DB adapter automatically converts the db value to a JS date via the Date constructor, which for the zero'd value above gives an Invalid Date.

I was creating a custom date type with the serialize function as follows:

serialize: function(value : Date) {
    if (isNaN(value.getTime()) {
        return null
    }

    return customDateFormatter(value)     
},

The problem is that if you return null from the serialize function, graphql will automatically throw an error on your behalf (

In execute.js completeValue:

Considering that I can happily throw a handled exception from within the serialize function, how come you chose to also automatically throw one for me?

I can think of a lot of use cases where you might want to silently ignore the fact that serialize returns null.

Is it possible to get a way to make graphql-js allow a serialize function to return null?