GraphQL Tutorial - Expected undefined to be a GraphQL schema

Question

I try to learn GraphQL. I created a project and I did what this page says.

Install

   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

This returns me an error.

    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)

Versions

• graphql: "^16.0.1"
• node : v16.13.0

Answer 1

I was following the same tutorial and I had the same problem. After going to the next page, as U Rogel suggested, I had the following problem:

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

So, I decided to modify my graphql version in the package.json

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

}

Then I ran npm install, went back to the first page, and I worked!
I think the problem is that version 16+ does not work with the basic examples.