GraphQL教程-预期未定义为GraphQL模式

Question

我试着学习GraphQL。我创建了一个项目，我做了此页说的。

安装

   npm init
   npm install graphql --save

Server.js

var { graphql, buildSchema } = require('graphql');

// Construct a schema, using GraphQL schema language
var schema = buildSchema(`
  type Query {
    hello: String
  }
`);

// The root provides a resolver function for each API endpoint
var root = {
  hello: () => {
    return 'Hello world!';
  },
};

// Run the GraphQL query '{ hello }' and print out the response
graphql(schema, '{ hello }', root).then((response) => {
  console.log(response);
});

Run

node server.js

这会给我一个错误。

    throw new Error(
          ^
Error: Expected undefined to be a GraphQL schema.
    at assertSchema (C:\Users\BK\Projects\Test\graphql-test\node_modules\graphql\type\schema.js:35:11)
    at validateSchema (C:\Users\BK\Projects\Test\graphql-test\node_modules\graphql\type\validate.js:34:28)
    at graphqlImpl (C:\Users\BK\Projects\Test\graphql-test\node_modules\graphql\graphql.js:52:64)
    at C:\Users\BK\Projects\Test\graphql-test\node_modules\graphql\graphql.js:21:43
    at new Promise (<anonymous>)
    at graphql (C:\Users\BK\Projects\Test\graphql-test\node_modules\graphql\graphql.js:21:10)
    at Object.<anonymous> (C:\Users\BK\Projects\Test\graphql-test\server.js:18:1)
    at Module._compile (node:internal/modules/cjs/loader:1101:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)

版本

• 图形："^16.0.1“
• 节点: v16.13.0

Answer 1

我遵循同样的教程，我也遇到了同样的问题。按照U Rogel的建议，进入下一页后，我遇到了以下问题：

Could not resolve dependency:
npm ERR! peer graphql@"^14.7.0 || ^15.3.0" from express-graphql@0.12.0
npm ERR! node_modules/express-graphql

因此，我决定修改package.json中的graphql版本

"dependencies": {
    "express": "^4.17.1",
    "express-graphql": "^0.12.0",
    "graphql": "^14.7.0"
}

然后我运行npm install，回到第一页，它成功了！

我认为问题在于16+版本与基本示例不兼容。