The difference between Falcor and GraphQL

falcorgraphqlrelayjs

GraphQL consists of a type system, query language and execution
semantics, static validation, and type introspection, each outlined
below. To guide you through each of these components, we've written an
example designed to illustrate the various pieces of GraphQL.

– https://github.com/facebook/graphql

Falcor lets you represent all your remote data sources as a single
domain model via a virtual JSON graph. You code the same way no matter
where the data is, whether in memory on the client or over the network
on the server.

– http://netflix.github.io/falcor/

What is the difference between Falcor and GraphQL (in the context of Relay)?

Best Answer

I have viewed the Angular Air Episode 26: FalcorJS and Angular 2 where Jafar Husain answers how GraphQL compares to FalcorJS. This is the summary (paraphrasing):

FalcorJS and GraphQL are tackling the same problem (querying data, managing data).
The important distinction is that GraphQL is a query language and FalcorJS is not.
When you are asking FalcorJS for resources, you are very explicitly asking for finite series of values. FalcorJS does support things like ranges, e.g. genres[0..10]. But it does not support open-ended queries, e.g. genres[0..*].
GraphQL is set based: give me all records where true, order by this, etc. In this sense, GraphQL query language is more powerful than FalcorJS.
With GraphQL you have a powerful query language, but you have to interpret that query language on the server.

Jafar argues that in most applications, the types of the queries that go from client to server share the same shape. Therefore, having a specific and predictable operations like get and set exposes more opportunities to leverage cache. Furthermore, a lot of the developers are familiar with mapping the requests using a simple router in REST architecture.

The end discussion resolves around whether the power that comes with GraphQL outweighs the complexity.

Purpose of `viewer` root query field

viewer is not something GraphQL or Relay-specific. Most web applications serve some purposes of its users or viewers. The top level entity to model the various data served to the user can be named as viewer. You can also name it user. For example, the Relay todo example has a viewer root query field:

viewer: {
  type: GraphQLUser,
  resolve: () => getViewer(),
},

We may also do without viewer. For instance, Relay starwars example does not have any viewer root query field.

In short, having this viewer as a root query field of the GraphQL schema enables us to provide data based on the current user.

Implementation: How to use authentication token together with viewer

My answer follows what is already described in your mentioned article. The steps are:

On the server-side, create a mutation to obtain an authentication token. Let's name it LoginMutation. Input to this mutation are the user credentials and the output is an authentication token.
On the client-side, if you use relay framework, implement a client-side mutation. After the mutation is successful, store the authentication token.
On the client-side Relay code, add authToken parameter for your viewer queries. The value of authToken is the authentication token received after successful login mutation.

An alternative

As already mentioned in the article, an alternative way of authenticating user is to do it outside of GraphQL. You may want to see two excellent answers this and this for details.

Jonas Helfer wrote a two-part article on this, which you'll find very useful: Part 1, Part 2

Best Answer

Related Solutions

Github – Flow text around an image in (GitHub) Markdown

The meaning of viewer field in GraphQL

Purpose of viewer root query field

Implementation: How to use authentication token together with viewer

An alternative

Related Topic

Purpose of `viewer` root query field