GraphQL（Apollo）：您可以在resolve函數中訪問指令嗎？

Question

我想將每個字段都設為私有，除非另有指示。 是否有可能在resolve函數中獲取此信息？

const typeDefs = gql`
  directive @public on FIELD_DEFINITION

  type Query {
    viewer: User @public
    secret: String
  }

  type User {
    id: ID!
  }
`

const schema = makeExecutableSchema({
  typeDefs,
  resolvers,
});

addSchemaLevelResolveFunction(schema, (parent, args, params, info) => {
  // Not possible
  if (info.fieldName.directive === 'public') {
    return parent;
  }

  throw new Error('Authentication required...');
});

const server = new ApolloServer({ schema });

Answer 1

雖然在fieldNodes數組的FieldNode對象上有一個directives屬性， FieldNode據我所知，它沒有填充適用於該特定字段的偽指令。

指令並不是真的要用作可在解析程序中引用的內容（架構級別或其他）的標志。 您可以考慮在指令的visitFieldDefinition函數中移動邏輯：

const { defaultFieldResolver } = require('graphql')
const { SchemaDirectiveVisitor } = require('graphql-tools')

class PublicDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field) {
    const { resolve = defaultFieldResolver } = field
    field.resolve = async function (source, args, context, info) {
      if (someCondition) {
        throw new SomeError()
      }
      return resolve.apply(this, [source, args, context, info])
    }
  }
}

const schema = makeExecutableSchema({
  typeDefs,
  resolvers,
  schemaResolvers: {
    public: PublicDirective,
  },
})