GraphQL 解析 GraphQLObjectType答案

【问题标题】：GraphQL resolve GraphQLObjectTypeGraphQL 解析 GraphQLObjectType
【发布时间】：2017-09-19 13:52:55
【问题描述】：

我正在使用express-graphql 以及以下查询：

invitations {
    sent 
    received
}

架构定义（简化）如下：

const InvitationType = new GraphQLObjectType({
    name: 'InvitationType',
    description: 'Friends invitations',
    fields: {
        sent: {
            type: new GraphQLList(GraphQLString),
            description: 'Invitations sent to friends.',
            resolve() {
             return ['sentA'];
            }
        },
        received: {
            type: new GraphQLList(GraphQLString),
            description: 'Invitations received from friends.',
            resolve() {
             return ['receivedA', 'receivedB'];
            }
        }
    }
});

// Root schema
const schema = new GraphQLSchema({
    query: new GraphQLObjectType({
      name: 'RootQueryType',
      fields: {
          invitations: {
              type: InvitationType // no resolve() method here.
          }
      }
    })
});

但是，resolve 方法永远不会为 sent 和 received 字段调用。上面的查询返回：

{data: {invitations: {sent: null, received: null}}}

有没有办法解决嵌套字段（sent 和 received）而不在父字段（invitations）上定义 resolve() 方法？

【问题讨论】：

标签： javascript express graphql

【解决方案1】：

这对我有用！根据GraphQL Documentation，如果resolve方法返回一个非标量，执行将继续。所以下面的代码有效：

// Root schema
const schema = new GraphQLSchema({
    query: new GraphQLObjectType({
      name: 'RootQueryType',
      fields: {
        invitations: {
          type: InvitationType,
          resolve: () => ({}) // Resolve returns an object.
        }
      }
    })
});

希望这会有所帮助。干杯！

【讨论】：