SDL as an Artifact: Code-First Schemas and GraphQL Nexus

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SDL as an Artifact: Code-ﬁrst Schemas and GraphQL Nexus @tgriesser

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Tim Griesser @tgriesser “Fast, reliable testing for anything that runs in a browser”

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❤

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❤ A Brief Timeline

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2015: graphql-js

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Later 2015 graph.ql 2015: graphql-js

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Original “SDL First” Library: Released November 2015

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Later 2015 - 2016: graph.ql graphql-tools 2015: graphql-js

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2015: graphql-js Later 2015 - 2016: graph.ql graphql-tools 2017: Graphene (Python)

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– Me, when beginning to use Graphene “Oh no, this library doesn’t develop the SDL ﬁrst”

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…a few months pass

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– Me, after spending a few more months in Graphene “Hey, this is actually pretty nice… scales really well to multiple teams”

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Stats from Generated SDL: 307 object types 129 input types 89 enum types 10 interfaces 5 custom scalars 1 union type 0 custom directives 2542 output ﬁelds 581 input ﬁelds 717 enum members 35 deprecations ~ 18 developers, 4 teams contributing to the same schema

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GitHub Public API SDL: 326 object types 90 input types 70 enum types 25 interfaces 8 custom scalars 20 union types 0 custom directives 2085 output ﬁelds 307 input ﬁelds 299 enum members 6 deprecations https://github.com/octokit/graphql-schema

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2015: graphql-js Later 2015 - 2016: graph.ql graphql-tools 2017: Graphene (Python) 2018: GraphQL Ruby

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2015: graphql-js Later 2015 - 2016: graph.ql graphql-tools 2017: Graphene (Python) 2018: GraphQL Ruby Also 2018: graphql-tools + graphql-code-generator

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– Marc-André Giroux during Q&A after at GraphQL NYC “…I’m not sure - SDL ﬁrst seems to be unique to the JavaScript community”

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…it feels like the JavaScript ecosystem is missing out

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Maybe we’re doing it wrong?

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What might a better “code ﬁrst” approach look like?

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GraphQL Nexus: An improved experience building code-ﬁrst schemas in JavaScript & TypeScript

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Why not SDL ﬁrst?

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GraphQL Nexus Why not SDL ﬁrst?

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Related Tooling in the Ecosystem GraphQL Nexus Why not SDL ﬁrst?

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Why not SDL ﬁrst? Related Tooling in the Ecosystem GraphQL Nexus How SDL is Still Incredibly Useful

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Why not SDL ﬁrst?

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Code Duplication

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“Double Declaration Problem”

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Implemented 16 times in GitHub’s Public API… Adding a new field with SDL first would mean finding all 16 locations and adding the new field

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Code Duplication Documentation / Type Ordering

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Code Duplication Documentation / Type Ordering Building For Larger Teams

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Code Duplication Documentation / Type Ordering Building For Larger Teams Tooling Complexity

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Code Duplication Documentation / Type Ordering Building For Larger Teams Tooling Complexity Microservices??

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https://nexus.js.org

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Code First

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Code First Declarative

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Code First Declarative Type-Safe

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Code First Declarative Type-Safe JavaScript Friendly

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Code First Declarative Type-Safe JavaScript Friendly Opinionated

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Code First Declarative Type-Safe JavaScript Friendly Opinionated** **but only slightly, conﬁgurable, and hopefully not too controversial

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What makes it different??

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Development Feedback Loop

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“makeSchema”  Generates Types

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“makeSchema”  Generates Types Generated types are   Inferred by  TypeScript Outputs SDL Schema Artifact Creates GraphQL schema Outputs TypeScript Types Imported type “registry” wired up

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“makeSchema”  Generates Types Generated types are   Inferred by  TypeScript Changes to  Schema, Restart   the Server IDE Auto-Completion & Type Checking Optional for JS development

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“makeSchema”  Generates Types Generated types are   Inferred by  TypeScript Changes to  Schema, Restart   the Server Regenerates SDL & Types ﬁles

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Type-Safety

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Generated in Development

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Generates a normal schema

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How? Conditional Types + Global Declaration Merging

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What’s the resolver return type?

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What’s the resolver return type? "Droid", "primaryFunction"

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What’s the resolver return type (continued)?

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What’s the resolver return type (continued)? You don’t need to worry about this…

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Does the ﬁeld need a resolver?

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End Result: Type-safety with less typing

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Dynamic Methods: Building custom, type-safe abstractions

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Connections:

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Customize object construction for your use cases

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Customize object construction for your use cases

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Auto-generated

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Makes something previously complicated simple

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Nexus Plugins: User-deﬁned, type-safe additions

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Augmenting library behavior (runtime and types) based on user deﬁned constructs

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Example: nexus-prisma +

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Opinions: Nullability

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– GraphQL Documentation “... in a GraphQL type system, every ﬁeld is nullable by default. This is because there are many things which can go awry in a networked service backed by databases and other services. A database could go down, an asynchronous action could fail, an exception could be thrown. Beyond simply system failures, authorization can often be granular, where individual ﬁelds within a request can have different authorization rules.”

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Exceptional States Should be Exceptional: “null” to indicate network failure should be declared & documented

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Conﬁgurable, schema level or type level

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The SDL Converter

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Paste your SDL endpoint thanks @swcarlosrj

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The Bad Parts Rough Edges

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“makeSchema”  Generates Types Generated types are   Inferred by  TypeScript Changes to  Code, Restarts  the Server Requires Some Conﬁguration ?? Chicken / Egg Problem TypeScript errors are sometimes cryptic Dynamic Types & Jump To Code

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Other Code-First Tooling

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What’s Next?

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“Dynamic Methods” Type-Safe “Plugin” System Progammatic Directives Better interop with SDL snippets