The compiler does the work before your app runs

relay-compiler reads every graphql tag in the project, validates it against schema.graphql, and writes an artifact per fragment and operation: a precomputed runtime AST, TypeScript types, and (here) a persisted query id. Pick any artifact this app generated.

Kind

query

Artifact size

4.5 KB

Operation text

343 B

What the browser sends

45 B + vars

1 · You write

src/components/advanced/DeferDemo.tsx

query DeferDemoOffQuery($id: ID!) {
  post(id: $id) {
    ...DeferDemo_post
    ...DeferDemoInsights_post
  }
}

2 · Types you import

DeferDemoOffQuery.graphql.ts

export type DeferDemoOffQuery$variables = {
  id: string;
};
export type DeferDemoOffQuery$data = {
  readonly post: {
    readonly " $fragmentSpreads": FragmentRefs<"DeferDemoInsights_post" | "DeferDemo_post">;
  } | null | undefined;
};
export type DeferDemoOffQuery = {
  response: DeferDemoOffQuery$data;
  variables: DeferDemoOffQuery$variables;
};

3 · Operation text, persisted at build time

md5 6b1dbc1c627cb4d13a0ed00cca74779c

Fragments from every component are inlined into one document. It lives in persisted_queries.json on the server; the client only knows the hash.

query DeferDemoOffQuery(
  $id: ID!
) {
  post(id: $id) {
    ...DeferDemo_post
    ...DeferDemoInsights_post
    id
  }
}

fragment DeferDemoInsights_post on Post {
  insights {
    readMinutes
    wordCount
    sentiment
    related
  }
}

fragment DeferDemo_post on Post {
  title
  excerpt
  author {
    name
    avatarColor
    id
  }
}

4 · Runtime artifact

imported in place of the graphql`` tag

A preprocessed AST, so there's no GraphQL parsing in the browser. The reader part tells useFragment what to read; the normalization part tells the store how to write.

/**
 * @generated SignedSource<<3359e9200759d9b23083077d467c2844>>
 * @relayHash 6b1dbc1c627cb4d13a0ed00cca74779c
 * @lightSyntaxTransform
 */

/* tslint:disable */
/* eslint-disable */
// @ts-nocheck

// @relayRequestID 6b1dbc1c627cb4d13a0ed00cca74779c

import { ConcreteRequest } from 'relay-runtime';
import { FragmentRefs } from "relay-runtime";
export type DeferDemoOffQuery$variables = {
  id: string;
};
export type DeferDemoOffQuery$data = {
  readonly post: {
    readonly " $fragmentSpreads": FragmentRefs<"DeferDemoInsights_post" | "DeferDemo_post">;
  } | null | undefined;
};
export type DeferDemoOffQuery = {
  response: DeferDemoOffQuery$data;
  variables: DeferDemoOffQuery$variables;
};

const node: ConcreteRequest = (function(){
var v0 = [
  {
    "defaultValue": null,
    "kind": "LocalArgument",
    "name": "id"
  }
],
v1 = [
  {
    "kind": "Variable",
    "name": "id",
    "variableName": "id"
  }
],
v2 = {
  "alias": null,
  "args": null,
  "kind": "ScalarField",
  "name": "id",
  "storageKey": null
};
return {
  "fragment": {
    "argumentDefinitions": (v0/*:: as any*/),
    "kind": "Fragment",
    "metadata": null,
    "name": "DeferDemoOffQuery",
    "selections": [
      {
        "alias": null,
        "args": (v1/*:: as any*/),
        "concreteType": "Post",
        "kind": "LinkedField",
        "name": "post",
        "plural": false,
        "selections": [
          {
            "args": null,
            "kind": "FragmentSpread",
            "name": "DeferDemo_post"
          },
          {
            "args": null,
            "kind": "FragmentSpread",
            "name": "DeferDemoInsights_post"
          }
        ],
        "storageKey": null
      }
    ],
    "type": "Query",
    "abstractKey": null
  },
  "kind": "Request",
  "operation": {
    "argumentDefinitions": (v0/*:: as any*/),
    "kind": "Operation",
    "name": "DeferDemoOffQuery",
    "selections": [
      {
        "alias": null,
        "args": (v1/*:: as any*/),
        "concreteType": "Post",
        "kind": "LinkedField",
        "name": "post",
        "plural": false,
        "selections": [
          {
            "alias": null,
            "args": null,
            "kind": "ScalarField",
            "name": "title",
            "storageKey": null
          },
          {
            "alias": null,
            "args": null,
            "kind": "ScalarField",
            "name": "excerpt",
            "storageKey": null
          },
          {
            "alias": null,
            "args": null,
            "concreteType": "User",
            "kind": "LinkedField",
            "name": "author",
            "plural": false,
            "selections": [
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "name",
                "storageKey": null
              },
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "avatarColor",
                "storageKey": null
              },
              (v2/*:: as any*/)
            ],
            "storageKey": null
          },
          {
            "alias": null,
            "args": null,
            "concreteType": "PostInsights",
            "kind": "LinkedField",
            "name": "insights",
            "plural": false,
            "selections": [
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "readMinutes",
                "storageKey": null
              },
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "wordCount",
                "storageKey": null
              },
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "sentiment",
                "storageKey": null
              },
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "related",
                "storageKey": null
              }
            ],
            "storageKey": null
          },
          (v2/*:: as any*/)
        ],
        "storageKey": null
      }
    ]
  },
  "params": {
    "id": "6b1dbc1c627cb4d13a0ed00cca74779c",
    "metadata": {},
    "name": "DeferDemoOffQuery",
    "operationKind": "query",
    "text": null
  }
};
})();

(node as any).hash = "b16899c6fe997779dd1599888f1d9331";

export default node;

why it mattersA typo in a field name fails the build, not the user's session. Every fragment is checked against the schema on every save.
why it mattersTypes come from the fragment rather than the whole schema, so a component's data type has exactly the fields it asked for.
why it mattersPersisted queries ship for free: smaller requests, cacheable GETs, and a server that can refuse any query it didn't compile.