Comment on a payé notre dette technique avec GraphQL

Luc Momal
Staff Engineer @

The birth of legacy code.

Entities, such as workers, companies, contracts, invoices ..

Our story starts in 2015

Some years
later

I don't like spaghetti.. bye bye !

Let's reconstruct
everything! 🥳

I don't like spaghetti.. bye bye !

~~6 months~~
1 year later

BIG BANG!!!!!

Synchronization!!

BIG BANG!!!!!

GraphQL to the rescue.

GraphQL

GraphQL is a PATTERN not a technology

GraphQL is a query language for your API

GraphQL is a replacement for REST

GraphQL

type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

GraphQL

type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

GraphQL

type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

GraphQL


type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

const resolvers = {
  Query: {
    worker: (parent, args, ctx) => db.worker.get(args.id)
  },
  
  Worker: {
    id: (parent) => parent.id,
    firstName: (parent) => parent.firstName,
    lastName: (parent) => parent.lastName,
    contracts: (parent) => db.contracts.getFromWorker(parent.id)
  },
  
  Contract: {
    from: (parent) => parent.from,
    to: (parent) => parent.to,
    company: (parent) => db.company.get(parent.companyId),
  },
  
  Company: {
    name: (parent) => parent.name 
  }
}

GraphQL


type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

const resolvers = {
  Query: {
    worker: (parent, args, ctx) => db.worker.get(args.id)
  },
  
  Worker: {
    id: (parent) => parent.id,
    firstName: (parent) => parent.firstName,
    lastName: (parent) => parent.lastName,
    contracts: (parent) => db.contract.getFromWorker(parent.id)
  },
  
  Contract: {
    from: (parent) => parent.from,
    to: (parent) => parent.to,
    company: (parent) => db.company.get(parent.companyId),
  },
  
  Company: {
    name: (parent) => parent.name 
  }
}

GraphQL


type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

const resolvers = {
  Query: {
    worker: (parent, args, ctx) => db.worker.get(args.id)
  },
  
  Worker: {
    id: (parent) => parent.id,
    firstName: (parent) => parent.firstName,
    lastName: (parent) => parent.lastName,
    contracts: (parent) => db.contracts.getFromWorker(parent.id)
  },
  
  Contract: {
    from: (parent) => parent.from,
    to: (parent) => parent.to,
    company: (parent) => db.company.get(parent.companyId),
  },
  
  Company: {
    name: (parent) => parent.name 
  }
}

GraphQL


type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

const resolvers = {
  Query: {
    worker: (parent, args, ctx) => db.worker.get(args.id)
  },
  
  Worker: {
    id: (parent) => parent.id,
    firstName: (parent) => parent.firstName,
    lastName: (parent) => parent.lastName,
    contracts: (parent) => db.contracts.getFromWorker(parent.id)
  },
  
  Contract: {
    from: (parent) => parent.from,
    to: (parent) => parent.to,
    company: (parent) => db.company.get(parent.companyId),
  },
  
  Company: {
    name: (parent) => parent.name 
  }
}

AMAZING!

GraphQL


type Query {
  worker(id: ID!): Worker
}

type Worker {
  id: ID!
  firstName: String
  lastName: String
  contracts: [Contract]
}

type Contract {
  from: Date
  to: Date
  company: Company
}

type Company {
  name: String
}

query {
  worker(id: 42) {
   id
   firstName
   contracts {
     company {
       name
     }
   }
  }
}

{
  worker: {
    id: 42,
    firstName: "John",
    contracts: [
      {
        company: {
          name: "cie"
        }
      }
    ]
  }
}

const resolvers = {
  Query: {
    worker: (parent, args, ctx) => db.worker.get(args.id)
  },
  
  Worker: {
    id: (parent) => parent.id,
    firstName: (parent) => parent.firstName,
    lastName: (parent) => parent.lastName,
    contracts: (parent) => db.contracts.getFromWorker(parent.id)
  },
  
  Contract: {
    from: (parent) => parent.from,
    to: (parent) => parent.to,
    company: (parent) => db.company.get(parent.companyId),
  },
  
  Company: {
    name: (parent) => parent.name 
  }
}

AMAZING!

Mmh, no!!!!

It's time to pay our debt

Mmh, no!!!!

Migration of our last v1 feature.

GET /workers/42/contracts

{
  worker: {
    id: 42,
    firstName: "John",
    lastName: "Doe",
    birthDate: "31/08/1989",
    //etc...
    contracts: [
      {
        company: {
          name: "cie",
          invoiceSettings: {},
          contacts: {},
          //etc...
        }
      }
    ]
  }
}

❌ Mmh, no!!!!

read only

GraphQL to create a new interface

REST call

read only

Data model improvement

read only


type Mission { 
   from: String
   to: String
   contracts: [Contract]
   company: Company
   worker: Worker
}

type Contract {
   type: String
   from: String
   to: String
}

GraphQL to migrate


{
    "company_name": "ABC Corp",
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "CA",
        "zip": "12345"
    },
    "invoicing_settings": {
        "currency": "USD",
        "tax_rate": 0.08,
        "invoice_terms": "Payment due within 30 days",
        "invoice_footer": "Thank you for your business!"
    },
    "jobs": [...],
    "contacts": [...],
    ...
}

All information related to a company is stored

in a single location in v1.

All information related to a company is stored

in a single location in v1.

GraphQL to migrate


const Company = {
    "company_name": "ABC Corp",
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "CA",
        "zip": "12345"
    },
}

const CompanyInvoicingSettings = {
    "invoicing_settings": {
        "currency": "USD",
        "tax_rate": 0.08,
        "invoice_terms": "Payment due within 30 days",
        "invoice_footer": "Thank you for your business!"
    },
}

const CompanyJobs = {
    "jobs": [...],
}

const CompanyContacts = {
    "contacts": [...],
}

These data can be easily split into several parts.

GraphQL to migrate

type Company {
    name: String
    street: String
    city: String
    state: String
    zip: String
    invoicing: CompanyInvoicingSettings
    job: CompanyJob
	contacts: CompanyContacts
}

type CompanyInvoicingSettings {
  currency: String
  tax_rate: String
  invoice_terms: String
  invoice_footer: String
}

type CompanyJob {
   title: String
   location: String
}

type CompanyContacts {
  name: String
  email: String
  phone: String
}

And we can easily create

a graphql schema

for those data

GraphQL to migrate

With Federation

you can merge

your graph! 🚀

GraphQL to migrate

With Federation

you can merge

your graph! 🚀

Comment on a payé notre dette technique avec GraphQL

The birth of legacy code.

Our story starts in 2015

Some years later

BIG BANG!!!!!

BIG BANG!!!!!

BIG BANG!!!!!

BIG BANG!!!!!

GraphQL to the rescue.

GraphQL

GraphQL

GraphQL

GraphQL

GraphQL

GraphQL

GraphQL

GraphQL

GraphQL

It's time to pay our debt

Migration of our last v1 feature.

GraphQL to create a new interface

Data model improvement

GraphQL to migrate

GraphQL to migrate

GraphQL to migrate

GraphQL to migrate

GraphQL to migrate

GraphQL to migrate

Thank you for listening

Some years
later