GraphQL & Relay notes (December 2015)

Relay Notes
===========

 - Define a schema, that is used for _both_ server side endpoint setup & frontend graphql compilation
 - node only for now, some graphql ports
 - Relay has a strict specification of how a graphql schema is set up: https://facebook.github.io/relay/docs/graphql-relay-specification.html

 - tree children are called "plural links" (see _writePluralLink())


Bad points
----------
 - Complex, many new concepts
 - Proprietary format
 - Reminds me of (the bad points about) SOAP, RequestFactory
 - Errors are returned as 200
  - No tracebacks if a serverside exception occurs (with graphqllib)
  - Error reporting in general isn't the greatest: "null parameter: AttributeError: 'AttributeError' object has no attribute 'message'" with graphqllib
  - GraphQLError wrappers hide tracebacks
  - errors: null, errors: [] both raise errors on the client
 - Root query args must be string, otherwise get some weird invariant violation
 - finding answers to q's is hard, a fledgling community
 - specifying fragments is hard with mutations & composition

Gotchas
-------
 - input into a mutation must be relay output
 - optimistic responses must have an id
 - optional args must be declared, and must be null
 - IMPORTANT: Components can only see the data they queried.  If you have child objects that have a field used for keys, make sure to include that field in the query fragment
 - And don't be cloning relay props neither, they are of a certain type
 - Some operations don't diff properly, eg delete from children, so need to fudge parent field (add a space for eg) in order to make the diff work

Django integration possibilities
--------------------------------
 - Existing need due for isomorphic react apps
 - exec node script, call python from node with node-python npm package
 -

Links
-----
 - https://facebook.github.io/react/blog/2015/03/19/building-the-facebook-news-feed-with-relay.html
 - http://blog.startifact.com/posts/the-emerging-graphql-python-stack.html