Support setting headers and credentials from context

[leethree]

Currently context.headers are being ignored by apollo-upload-client, which is different from the behaviour of apollo-link-http.

See https://github.com/apollographql/apollo-link/blob/9fa5b4dc9cd67577fd118e1f437b2138fe3cd8eb/packages/apollo-link-http/src/httpLink.ts#L114-L119 , headers and credentials from context should merge with fetcherOptions.

[jaydenseric]

That's a deliberate API divergence, you can set headers and credentials via context by using fetchOptions (also works in apollo-link-http):

const authLink = new ApolloLink((operation, forward) => {
    const viewerToken = getViewerToken()
    if (viewerToken)
      operation.setContext({
        fetchOptions: {
          headers: {
            authorization: `Bearer ${viewerToken}`
          }
        }
      })
    return forward(operation)
  })

[leethree]

OK! The workaround looks good to me. Would be great if this behaviour is documented.

Thanks a lot!

[jaydenseric]

With [email protected] you should be able to set credentials and headers directly on the link and via context. Please test it out!

[leethree]

Just upgraded and it's working well. Thanks!