Make null value configurable, to allow undefined

undefined is practical in JS for destructuring default, so it would be great to allow graphql to avoid converting undefined to null

I see some return null or return Promise.resovle(null) frequently in the sources, how about using a NULL configuration variable, defaulting to null

[leebyron]

Thanks for this extra info. This makes way more sense now.

Unfortunately this isn’t something GraphQL.js would consider adding since it breaks some of the core constraints of the spec - which is that you will get a field in the result for every field you ask for in the query. Because of how JSON serializes data, undefined values imply removal of fields, which breaks this core constraint.

JavaScript is also a bit strange in this respect, since most languages do not have a concept of a runtime value for undefined. Since GraphQL.js seeks to be a reference implementation for other GraphQL libraries built in other languages, it’s important to remain close to the spec.

In this way, null and undefined actually have special meaning to GraphQL results outside of typical results. null means that the field requested is not available (either due to being non-existent or from an error) while undefined (or absent from response) means that the field was not requested.

To preserve the differences between null and undefined values as typical values rather than special meaning - perhaps because either you intend to translate to a transport mechanism different from JSON where undefined values are preserved (is there such a thing?) or you don’t intend to send the results over the network at all - then I would suggest taking a look at some of the libraries that offer resolver middleware to replace undefined with a different placeholder value.

[caub]

undefined (from server-side) also reduces JSON responses size