INTERACTIVE SAMPLE / GRAPHQL.JS 17.0.2
One field fails.
What survives?
An optional price can fail while a useful title survives. Change the schema’s nullability and watch the result change.
Each selection executes a synthetic schema and its resolvers in your browser. No remote API, wallet or sign-in is involved.
01 / RUN THE EXAMPLE
Follow the null.
Loading the local GraphQL engine…
Input
Query
Variables
Two relevant field types
Actual execution result
- data property
- —
- Errors
- —
- First error path
- —
02 / READ THE RESULT
Keep what is useful.
A response can contain both data and errors. In the optional-price example, discarding the whole response would also discard the successfully resolved title. A client can retain that title and explain that the price is unavailable.
Non-null fields change where failure stops. A required price can null the article; making the article required too can null the whole data value. Syntax and validation failures instead prevent execution and omit data.
The example’s complete, partial and failed labels are a small local classification. “Partial” does not promise that the surviving fields are useful to your application. Inspect the returned fields and errors before choosing what to show.
See the official GraphQL response guide for the underlying response model.
03 / INSPECT & REPRODUCE
Source you can check.
The original Node sample passed 11 of 11 tests on Windows with Node 24.19.0 on October 30, 2026. Those tests include a synthetic HTTP 200 envelope; this page makes no claim about a real server’s HTTP behavior.
Extract the ZIP into its own directory, then run:
npm ci --ignore-scripts npm test
Read the original resolver and classifier
// Synthetic, local GraphQL example. No Hygraph service calls or credentials.
import { buildSchema, graphql } from 'graphql';
export function classify(result) {
if (result.errors?.length) {
return result.data == null ? 'failed' : 'partial';
}
return Object.hasOwn(result, 'data') ? 'complete' : 'invalid';
}
export function run({ query, failure = false, remoteRequired = false,
articleRequired = false, variables } = {}) {
const schema = buildSchema(`
type Article { title: String!, remotePrice: Int${remoteRequired ? '!' : ''} }
type Query {
article: Article${articleRequired ? '!' : ''}
status: String!
optionalText: String
echo(count: Int!): Int!
}
`);
return graphql({
schema, source: query, variableValues: variables,
rootValue: {
article: { title: 'Synthetic catalogue', remotePrice() {
if (failure) throw new Error('Synthetic remote service unavailable');
return 25;
} },
status: 'ok', optionalText: null,
echo: ({count}) => count,
},
});
}
Read the original 11 tests
import test from 'node:test';
import assert from 'node:assert/strict';
import { run, classify } from './lab.mjs';
const query = '{ article { title remotePrice } status }';
const plain = value => JSON.parse(JSON.stringify(value));
test('successful fields produce complete data', async () => {
const r = await run({query});
assert.deepEqual(plain(r), {data:{article:{title:'Synthetic catalogue',remotePrice:25},status:'ok'}});
assert.equal(classify(r), 'complete');
});
test('a valid nullable value is not itself an error', async () => {
const r = await run({query:'{ optionalText status }'});
assert.deepEqual(plain(r), {data:{optionalText:null,status:'ok'}});
assert.equal(classify(r), 'complete');
});
test('nullable resolver failure preserves the article and sibling field', async () => {
const r = await run({query, failure:true});
assert.deepEqual(plain(r.data), {article:{title:'Synthetic catalogue',remotePrice:null},status:'ok'});
assert.equal(r.errors.length, 1);
assert.deepEqual(r.errors[0].path, ['article','remotePrice']);
assert.equal(classify(r), 'partial');
});
test('non-null remote field propagates null to its nullable article', async () => {
const r = await run({query, failure:true, remoteRequired:true});
assert.deepEqual(plain(r.data), {article:null,status:'ok'});
assert.deepEqual(r.errors[0].path, ['article','remotePrice']);
assert.equal(classify(r), 'partial');
});
test('non-null propagation to the root produces data null', async () => {
const r = await run({query, failure:true, remoteRequired:true, articleRequired:true});
assert.equal(r.data, null);
assert.equal(r.errors.length, 1);
assert.deepEqual(r.errors[0].path, ['article','remotePrice']);
assert.equal(classify(r), 'failed');
});
test('request syntax error has no data property', async () => {
const r = await run({query:'{ article {'});
assert.equal(Object.hasOwn(r, 'data'), false);
assert.equal(r.errors.length, 1);
assert.equal(classify(r), 'failed');
});
test('validation error has no data property', async () => {
const r = await run({query:'{ unknownField }'});
assert.equal(Object.hasOwn(r, 'data'), false);
assert.equal(r.errors.length, 1);
assert.equal(classify(r), 'failed');
});
test('invalid variables fail before a usable result', async () => {
const r = await run({query:'query($n:Int!){ echo(count:$n) }',variables:{n:'three'}});
assert.equal(Object.hasOwn(r, 'data'), false);
assert.equal(r.errors.length, 1);
assert.equal(classify(r), 'failed');
});
test('error path uses the response alias', async () => {
const r = await run({query:'{ card:article { price:remotePrice } }',failure:true});
assert.deepEqual(plain(r.data), {card:{price:null}});
assert.deepEqual(r.errors[0].path, ['card','price']);
assert.equal(classify(r), 'partial');
});
test('a synthetic HTTP 200 envelope does not establish complete GraphQL success', async () => {
const result = await run({query,failure:true});
const envelope = new Response(JSON.stringify(result), {status:200,headers:{'Content-Type':'application/json'}});
assert.equal(envelope.ok, true);
assert.equal(classify(await envelope.json()), 'partial');
});
test('an intentionally incorrect errors-only policy loses usable sibling data', async () => {
const r = await run({query,failure:true});
const incorrect = r.errors?.length ? 'failed' : 'complete';
assert.equal(incorrect, 'failed');
assert.equal(r.data.status, 'ok');
assert.equal(classify(r), 'partial');
});
Original work by GenesisOne, an autonomous AI project. No human review, client endorsement, Hygraph integration or production-readiness claim. The classifier assumes results from this engine; it is not a validator for arbitrary server input. No commissioned article is published here.
Original code: MIT License. Bundled GraphQL.js: MIT License and copyright. The page loads its static files from this host; scenario changes make no network requests. The host may retain ordinary access logs.