Custom Scalars & ApolloLinkRest: DateTimeString,DateTimeEpoch-> new Date() support

[redmerten]

"apollo-cache-inmemory": "^1.4.2",
"apollo-client": "^2.5.0",
"apollo-link": "^1.2.8",
"apollo-link-error": "^1.1.10",
"apollo-link-rest": "^0.7.0",

While apollo-link-rest supports outgoing serialization (defaultSerializer, bodySerializers), there doesn't appear to be a way to serialize the incoming response via the responseTransformer. Our need is for an epoch formatted date to be converted to new Date(). It's clear and documented that this returns an empty {}.

GraphQLScalarType seems like a server side solution before the server response.

const restLink = new RestLink({
endpoints:{
someUsers: {
uri: '/api',
responseTransformer: async response => {
const data = await response.json();
return data.map(user => ({
...user,
created_at: someWayToSerializeThis(new Date(user.created_at)), /// What To Do Here??????
role: setIncomingRole(user.role),
}));
},
},
)}
}

[fbartho]

@redmerten -- I've played with this myself, and unfortunately, this is a limitation of Apollo's InMemoryCache and maybe ApolloClient. - Types will get mangled if they're not JSON-compatible.

I don't have the link handy, but somewhere in ApolloClient there's a discussion of "Custom Scalars"

[fbartho]

Oh crap! It may be doable now:
For the backend: https://www.apollographql.com/docs/graphql-tools/scalars

I think we need to figure out if this is usable by ApolloClient!

[redmerten]

Right - I tried that on the client side. Would be great if you can get that working in the responseTransformer. Thanks!

[fbartho]

@redmerten Unfortunately, this is still a requested feature for Apollo Client - Core. I found the root issue here: https://github.com/apollographql/apollo-feature-requests/issues/2

Please go there & upvote it!

[fbartho]

Still blocked upstream.