预期可迭代，但未在字段“ Query.customers \”中找到一个

如何解决预期可迭代，但未在字段“ Query.customers \”中找到一个

我正在尝试学习GraphQL，但是当我尝试执行{customers {id，name}}时以及尝试使用突变或搜索特定客户时遇到错误。你能帮助我吗？ 我在解析器上控制台记录数据，一切都很好，但是我想问题出在数据类型上。我该如何解决？

这是我的typeDefs.js文件：

const { gql } = require("apollo-server-express");

const typeDefs = gql`
  type Customer {
    id: ID!
    name: String!
    email: String!
    age: Int!
  }

  type Query {
    customer(id: ID!): Customer
    customers: [Customer]!
  }

  type Mutation {
    addCustomer(name: String!,email: String!,age: String!): Customer!
    editCustomer(
      id: ID!
      name: String!
      email: String!
      age: String!
    ): Customer!
    deleteCustomer(id: ID!): Customer!
  }
`;

module.exports = typeDefs;

这是我的resolvers.js文件：

const axios = require("axios");

const resolvers = {
  Query: {
    customer: async (_,{ id }) => {
      const data = await axios.get("http://localhost:3000/customers/" + id);
      return data;
    },customers: async () => {
      const data = await axios.get("http://localhost:3000/customers/");
      return data;
    },},Mutation: {
    addCustomer: async (_,{ name,email,age }) => {
      const response = await axios.post("http://localhost:3000/customers",{
        name,age,});
      return response.data;
    },editCustomer: async (_,{ id,name,age }) => {
      const response = await axios.patch(
        "http://localhost:3000/customers" + id,{
          name,}
      );
      return response.data;
    },};

module.exports = resolvers;

我的数据位于json服务器中，格式为：

{
  "customers": [
    {
      "id": "1","name": "John Doe","email": "[e-mail]","age": 36
    },{
      "id": "2","name": "Keith Wilson","email": "[e-mail]","age": 50
    },{
      "id": "3","name": "Tom Jones","email": "[e-mail]","age": 23
    },{
      "id": "5","name": "Jen Thompson","email": "[e-mail]","age": 22
    }
  ]
}