GraphQL（Apollo）：您可以在resolve函数中访问指令吗？

Question

我想将每个字段都设为私有，除非另有指示。 是否有可能在resolve函数中获取此信息？

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

虽然在fieldNodes数组的FieldNode对象上有一个directives属性， FieldNode据我所知，它没有填充适用于该特定字段的伪指令。

指令并不是真的要用作可在解析程序中引用的内容（架构级别或其他）的标志。 您可以考虑在指令的visitFieldDefinition函数中移动逻辑：

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,
  },
})