types - 你如何在 GraphQL 中扩展类型？

Question

例如，Pet是 Animal与 owner和 name .

type Animal {
  species: String
}

type Pet extends Animal {
  owner: Owner
  name: String
}

Answer 1

从 June2018 stable version of the GraphQL spec 开始，一个 Object 类型可以扩展另一个 Object 类型:

Object type extensions are used to represent a type which has been extended from some original type. For example, this might be used to represent local data

在你的例子中，

type Animal {
  species: String
}

extend type Animal {
  owner: Owner
  name: String
}

这本身不是继承；您只能扩展基本类型，而不能基于它创建新类型。请注意，新类型没有名称；现有 Animal类型被扩展。

graphql.org documentation没有提及有关 extend 的任何内容，但文档是 admittedly lackluster并且正在 transitioned从 Facebook 的所有权到 Linux 基金会。
JavaScript 引用实现 doesn't fully support extensions ，但是因为您已经标记了您的问题 apollo-server ，您可以使用 graphql-tools , 其中 does :

const { graphql } = require('graphql');
const { makeExecutableSchema } = require('graphql-tools');

const typeDefs = `
  type Person {
    name: String!
  }
  extend type Person {
    salary: Int
  }  
  type Query {
    person: Person
  }
`;

const resolvers = {
  Query: {
    person: () => ({ name: "John Doe", salary: 1234 })
  }
}  

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

graphql(schema, '{ person {name salary} }').then((response) => {
  console.log(response);
});

对于实际的类型继承，请参见 graphql-s2s library .