为什么 GraphQL 不接受这种标量参数类型，而是抱怨 "argument type must be Input Type but got: undefined"？

Question

我有

export const getPicture = {
    type: GraphPicture,
    args: {
        type: new GraphQLNonNull(GraphQLInt)
    },
    resolve(_, args) {
        return Picture.findByPrimary(args.id);
    }
};

export const getPictureList = {
    type: new GraphQLList(GraphPicture),
    resolve(_, __, session) {
        return Picture.findAll({where: {owner: session.userId}});
    }
};

和

const query = new GraphQLObjectType({
    name: 'Queries',
    fields: () => {
        return {
            getPictureList: getPictureList,
            getPicture: getPicture
        }
    }
});

const schema = new GraphQLSchema({
    query: query,
    mutation: mutation
});

抛出：

Error: Queries.getPicture(type:) argument type must be Input Type but got: undefined.

getPictureList 工作正常； getPicture 失败，标量参数类型为 GraphQLInt 或 GraphQLNonNull(GraphQLInt)。我试过将 getPicture 变成 GraphQLLIst，但没有用。我曾尝试将参数 type 设为输入类型，但没有用。

为什么代码会产生错误，如何修复？

堆栈跟踪是：

Error: Queries.getPicture(type:) argument type must be Input Type but got: undefined.
    at invariant (/home/jrootham/dev/trytheseon/node_modules/graphql/jsutils/invariant.js:19:11)
    at /home/jrootham/dev/trytheseon/node_modules/graphql/type/definition.js:307:33
    at Array.map (native)
    at /home/jrootham/dev/trytheseon/node_modules/graphql/type/definition.js:304:52
    at Array.forEach (native)
    at defineFieldMap (/home/jrootham/dev/trytheseon/node_modules/graphql/type/definition.js:293:14)
    at GraphQLObjectType.getFields (/home/jrootham/dev/trytheseon/node_modules/graphql/type/definition.js:250:46)
    at /home/jrootham/dev/trytheseon/node_modules/graphql/type/schema.js:224:27
    at typeMapReducer (/home/jrootham/dev/trytheseon/node_modules/graphql/type/schema.js:236:7)
    at Array.reduce (native)
    at new GraphQLSchema (/home/jrootham/dev/trytheseon/node_modules/graphql/type/schema.js:104:34)
    at Object. (/home/jrootham/dev/trytheseon/server/graphQL.js:45:16)
    at Module._compile (module.js:399:26)
    at normalLoader (/usr/lib/node_modules/babel/node_modules/babel-core/lib/babel/api/register/node.js:160:5)
    at Object.require.extensions.(anonymous function) [as .js] (/usr/lib/node_modules/babel/node_modules/babel-core/lib/babel/api/register/node.js:173:7)
    at Module.load (module.js:345:32)
    at Function.Module._load (module.js:302:12)
    at Module.require (module.js:355:17)
    at require (internal/module.js:13:17)
    at Object. (/home/jrootham/dev/trytheseon/devServer.js:14:44)
    at Module._compile (module.js:399:26)
    at normalLoader (/usr/lib/node_modules/babel/node_modules/babel-core/lib/babel/api/register/node.js:160:5)

Answer 1

问题不在于查询的 return 类型，而在于您为参数指定的类型。

export const getPicture = {
    type: GraphPicture,
    args: {
        type: new GraphQLNonNull(GraphQLInt)
    },
    resolve(_, args) {
        return Picture.findByPrimary(args.id);
    }
};

假设您想要一个名为 "type" 的参数，它应该是：

export const getPicture = {
    type: GraphPicture,
    args: {
        type: {
             type: new GraphQLNonNull(GraphQLInt)
        }
    },
    resolve(_, args) {
        return Picture.findByPrimary(args.id);
    }
};

这是来自 graphql-js 存储库的示例：

hero: {
  type: characterInterface,
  args: {
    episode: {
      description: 'If omitted, returns the hero of the whole saga. If ' +
                   'provided, returns the hero of that particular episode.',
      type: episodeEnum
    }
  },
  resolve: (root, { episode }) => getHero(episode),
},

在此处查看 graphql-js 存储库中的完整架构：https://github.com/graphql/graphql-js/blob/master/src/tests/starWarsSchema.js

Answer 2

仅供参考，我来到这里搜索同样的错误，但不是使用 undefined，而是使用我自己的 Product 类型：

... argument * must be Input Type but got Product

事实证明，在 GraphQL 中，您传递给 Mutation 的内容应该是标量类型（字符串、整数...）或用户定义的 input 类型，不是 type 类型。

http://graphql.org/graphql-js/mutations-and-input-types/

input ProductInput {
  id: ID
  name: String
}

我试图传递我的产品 type：

type Product {
  id: ID
  name: String
}

这感觉有点多余，但猜猜，我会很高兴稍后将它分开。

为什么 GraphQL 不接受这种标量参数类型，而是抱怨 "argument type must be Input Type but got: undefined"？

Why doesn't GraphQL accept this scalar argument type, instead complaining "argument type must be Input Type but got: undefined"?

graphql