GraphQL Schemas & Resolvers

When this skill applies

Use this skill when your VTEX IO app needs to expose a GraphQL API — either for frontend React components to query, for other VTEX IO apps to consume, or for implementing custom data aggregation layers over VTEX Commerce APIs.

• Defining schemas in .graphql files in the /graphql directory
• Writing resolver functions in TypeScript in /node/resolvers/
• Configuring @cacheControl and @auth directives
• Wiring resolvers into the Service class

Do not use this skill for:

• Backend service structure and client system (use vtex-io-service-apps instead)
• Manifest and builder configuration (use vtex-io-app-structure instead)
• MasterData integration details (use vtex-io-masterdata instead)

Decision rules

• The graphql builder processes .graphql files in /graphql and merges them into a single schema.
• Split definitions across multiple files for maintainability: schema.graphql for root types, directives.graphql for directive declarations, types/*.graphql for custom types.
• Use @cacheControl(scope: PUBLIC, maxAge: SHORT|MEDIUM|LONG) on all public Query fields. PUBLIC = shared CDN cache, PRIVATE = per-user cache.
• Use @auth on all Mutations and on Queries that return sensitive or user-specific data.
• Never use @cacheControl on Mutations.
• Resolver function keys in the Service entry point MUST exactly match the field names in schema.graphql.
• Always use ctx.clients in resolvers for data access — never raw HTTP calls.

Recommended directory structure:

graphql/
├── schema.graphql        # Query and Mutation root type definitions
├── directives.graphql    # Custom directive declarations (@cacheControl, @auth)
└── types/
    ├── Review.graphql    # Custom type definitions
    └── Product.graphql   # One file per type for organization

Built-in directives:

• @cacheControl: scope (PUBLIC/PRIVATE), maxAge (SHORT 30s, MEDIUM 5min, LONG 1h)
• @auth: Enforces valid VTEX authentication token. Without it, unauthenticated users can call the endpoint.
• @smartcache: Automatically caches query results in VTEX infrastructure.

Hard constraints

Constraint: Declare the graphql Builder

Any app using .graphql schema files MUST declare the graphql builder in manifest.json. The graphql builder interprets the schema and registers it with the VTEX IO runtime.

Why this matters

Without the graphql builder declaration, the /graphql directory is completely ignored. Schema files will not be processed, resolvers will not be registered, and GraphQL queries will return "schema not found" errors. The app will link without errors but GraphQL will silently not work.

Detection

If you see .graphql files in a /graphql directory but the manifest does not include "graphql": "1.x" in builders, STOP and add the builder declaration.

Correct

{
  "builders": {
    "node": "7.x",
    "graphql": "1.x"
  }
}

Wrong

{
  "builders": {
    "node": "7.x"
  }
}

Missing "graphql": "1.x" — the /graphql directory with schema files is ignored. GraphQL queries return errors because no schema is registered. The app links successfully, masking the problem.

---

Constraint: Use @cacheControl on Public Queries

All public-facing Query fields (those fetching data that is not user-specific) MUST include the @cacheControl directive with an appropriate scope and maxAge. Mutations MUST NOT use @cacheControl.

Why this matters

Without @cacheControl, every query hits your resolver on every request — no CDN caching, no edge caching, no shared caching. This leads to unnecessary load on VTEX infrastructure, slow response times, and potential rate limiting. For public product data, caching is critical for performance.

Detection

If a Query field returns public data (not user-specific) and does not have @cacheControl, warn the developer to add it. If a Mutation has @cacheControl, STOP and remove it.

Correct

type Query {
  reviews(productId: String!, limit: Int): [Review]
    @cacheControl(scope: PUBLIC, maxAge: SHORT)

  productMetadata(slug: String!): ProductMetadata
    @cacheControl(scope: PUBLIC, maxAge: MEDIUM)

  myReviews: [Review]
    @cacheControl(scope: PRIVATE, maxAge: SHORT)
    @auth
}

type Mutation {
  createReview(review: ReviewInput!): Review @auth
}

Wrong

type Query {
  reviews(productId: String!, limit: Int): [Review]

  myReviews: [Review]
}

type Mutation {
  createReview(review: ReviewInput!): Review
    @cacheControl(scope: PUBLIC, maxAge: LONG)
}

No cache control on queries (every request hits the resolver), missing @auth on user-specific data, and @cacheControl on a mutation (makes no sense).

---

Constraint: Resolver Names Must Match Schema Fields

Resolver function keys in the Service entry point MUST exactly match the field names defined in schema.graphql. The resolver object structure must mirror the GraphQL type hierarchy.

Why this matters

The GraphQL runtime maps incoming queries to resolver functions by name. If the resolver key does not match the schema field name, the field will resolve to null without any error — a silent failure that is extremely difficult to debug.

Detection

If a schema field has no matching resolver key (or vice versa), STOP. Cross-check every Query and Mutation field against the resolver registration in node/index.ts.

Correct

type Query {
  reviews(productId: String!): [Review]
  reviewById(id: ID!): Review
}

// node/index.ts — resolver keys match schema field names exactly
export default new Service({
  graphql: {
    resolvers: {
      Query: {
        reviews: reviewsResolver,
        reviewById: reviewByIdResolver,
      },
    },
  },
})

Wrong

// node/index.ts — resolver key "getReviews" does not match schema field "reviews"
export default new Service({
  graphql: {
    resolvers: {
      Query: {
        getReviews: reviewsResolver,    // Wrong! Schema says "reviews", not "getReviews"
        getReviewById: reviewByIdResolver, // Wrong! Schema says "reviewById"
      },
    },
  },
})

Both fields will silently resolve to null. No error in logs.

Preferred pattern

Add the GraphQL builder to manifest:

{
  "builders": {
    "node": "7.x",
    "graphql": "1.x"
  }
}

Define the schema:

type Query {
  reviews(productId: String!, limit: Int, offset: Int): ReviewsResponse
    @cacheControl(scope: PUBLIC, maxAge: SHORT)

  review(id: ID!): Review
    @cacheControl(scope: PUBLIC, maxAge: SHORT)
}

type Mutation {
  createReview(input: ReviewInput!): Review @auth
  updateReview(id: ID!, input: ReviewInput!): Review @auth
  deleteReview(id: ID!): Boolean @auth
}

Define custom types:

type Review {
  id: ID!
  productId: String!
  author: String!
  rating: Int!
  title: String!
  text: String!
  createdAt: String!
  approved: Boolean!
}

type ReviewsResponse {
  data: [Review!]!
  total: Int!
  hasMore: Boolean!
}

input ReviewInput {
  productId: String!
  rating: Int!
  title: String!
  text: String!
}

Declare directives:

directive @cacheControl(
  scope: CacheControlScope
  maxAge: CacheControlMaxAge
) on FIELD_DEFINITION

enum CacheControlScope {
  PUBLIC
  PRIVATE
}

enum CacheControlMaxAge {
  SHORT
  MEDIUM
  LONG
}

directive @auth on FIELD_DEFINITION
directive @smartcache on FIELD_DEFINITION

Implement resolvers:

// node/resolvers/reviews.ts
import type { ServiceContext } from '@vtex/api'
import type { Clients } from '../clients'

type Context = ServiceContext<Clients>

export const queries = {
  reviews: async (
    _root: unknown,
    args: { productId: string; limit?: number; offset?: number },
    ctx: Context
  ) => {
    const { productId, limit = 10, offset = 0 } = args
    const reviews = await ctx.clients.masterdata.searchDocuments<Review>({
      dataEntity: 'reviews',
      fields: ['id', 'productId', 'author', 'rating', 'title', 'text', 'createdAt', 'approved'],
      where: `productId=${productId} AND approved=true`,
      pagination: { page: Math.floor(offset / limit) + 1, pageSize: limit },
      schema: 'review-schema-v1',
    })

    return {
      data: reviews,
      total: reviews.length,
      hasMore: reviews.length === limit,
    }
  },

  review: async (
    _root: unknown,
    args: { id: string },
    ctx: Context
  ) => {
    return ctx.clients.masterdata.getDocument<Review>({
      dataEntity: 'reviews',
      id: args.id,
      fields: ['id', 'productId', 'author', 'rating', 'title', 'text', 'createdAt', 'approved'],
    })
  },
}

export const mutations = {
  createReview: async (
    _root: unknown,
    args: { input: ReviewInput },
    ctx: Context
  ) => {
    const { input } = args

    const documentResponse = await ctx.clients.masterdata.createDocument({
      dataEntity: 'reviews',
      fields: {
        ...input,
        author: ctx.vtex.storeUserEmail ?? 'anonymous',
        approved: false,
        createdAt: new Date().toISOString(),
      },
      schema: 'review-schema-v1',
    })

    return ctx.clients.masterdata.getDocument<Review>({
      dataEntity: 'reviews',
      id: documentResponse.DocumentId,
      fields: ['id', 'productId', 'author', 'rating', 'title', 'text', 'createdAt', 'approved'],
    })
  },

  deleteReview: async (
    _root: unknown,
    args: { id: string },
    ctx: Context
  ) => {
    await ctx.clients.masterdata.deleteDocument({
      dataEntity: 'reviews',
      id: args.id,
    })

    return true
  },
}

Wire resolvers into the Service:

// node/index.ts
import type { ParamsContext, RecorderState } from '@vtex/api'
import { Service } from '@vtex/api'

import { Clients } from './clients'
import { queries, mutations } from './resolvers/reviews'

export default new Service<Clients, RecorderState, ParamsContext>({
  clients: {
    implementation: Clients,
    options: {
      default: {
        retries: 2,
        timeout: 5000,
      },
    },
  },
  graphql: {
    resolvers: {
      Query: queries,
      Mutation: mutations,
    },
  },
})

Testing the GraphQL API after linking:

query GetReviews {
  reviews(productId: "12345", limit: 5) {
    data {
      id
      author
      rating
      title
      text
      createdAt
    }
    total
    hasMore
  }
}

mutation CreateReview {
  createReview(input: {
    productId: "12345"
    rating: 5
    title: "Excellent product"
    text: "Really happy with this purchase."
  }) {
    id
    author
    createdAt
  }
}

Common failure modes

• Defining resolvers without matching schema fields: The GraphQL runtime only exposes fields defined in the schema. Resolvers without matching fields are silently ignored. Conversely, schema fields without resolvers return null. Always define the schema first, then implement matching resolvers with identical names.
• Querying external APIs directly in resolvers: Using fetch() or axios bypasses the @vtex/api client system, losing caching, retries, metrics, and authentication. Always use ctx.clients in resolvers.
• Missing @auth on mutation endpoints: Without @auth, any anonymous user can call the mutation — a critical security vulnerability. Always add @auth to mutations and queries returning sensitive data.
• Missing @cacheControl on public queries: Every request hits the resolver without caching, causing unnecessary load and slow responses. Add appropriate cache directives to all public Query fields.

Review checklist

• Is the graphql builder declared in manifest.json?
• Do all public Query fields have @cacheControl with appropriate scope and maxAge?
• Do all Mutations and sensitive Queries have @auth?
• Do resolver function keys exactly match schema field names?
• Are resolvers using ctx.clients for data access (no raw HTTP calls)?
• Are directive declarations present in directives.graphql?
• Is the resolver wired into the Service entry point under graphql.resolvers?

Related skills

• vtex-io-service-apps — Service app fundamentals needed for all GraphQL resolvers
• vtex-io-app-contract — Manifest and builder configuration that GraphQL depends on
• vtex-io-masterdata — MasterData integration commonly used as a data source in resolvers

Reference

• GraphQL in VTEX IO — Overview of GraphQL usage in the VTEX IO platform
• GraphQL Builder — Builder reference for schema processing and directory structure
• Developing a GraphQL API in Service Apps — Step-by-step tutorial for building GraphQL APIs
• Integrating an App with a GraphQL API — How to consume GraphQL APIs from other VTEX IO apps
• GraphQL authorization in IO apps — How to implement and use the @auth directive for protected GraphQL operations
• Implementing cache in GraphQL APIs for IO apps — How to implement and use the @cacheControl directive for GraphQL operations
• Clients — How to use ctx.clients in resolvers for data access