06

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
5.3 KB
Operation text
384 B
What the browser sends
45 B + vars

1 · You write

src/components/pagination/PaginationDemo.tsx
query PaginationDemoQuery {
  ...PaginationList_query
}

2 · Types you import

PaginationDemoQuery.graphql.ts
export type PaginationDemoQuery$variables = Record<PropertyKey, never>;
export type PaginationDemoQuery$data = {
  readonly " $fragmentSpreads": FragmentRefs<"PaginationList_query">;
};
export type PaginationDemoQuery = {
  response: PaginationDemoQuery$data;
  variables: PaginationDemoQuery$variables;
};

3 · Operation text, persisted at build time

md5 399bee76ad78574297166e3ef0b8cbd2

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 PaginationDemoQuery {
  ...PaginationList_query
}

fragment PaginationList_query on Query {
  feed(first: 3) {
    totalCount
    edges {
      cursor
      node {
        id
        title
        likeCount
        author {
          name
          avatarColor
          id
        }
        __typename
      }
    }
    pageInfo {
      endCursor
      hasNextPage
    }
  }
}

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<<3891d01700be8d89950b5c2e770c7679>>
 * @relayHash 399bee76ad78574297166e3ef0b8cbd2
 * @lightSyntaxTransform
 */

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

// @relayRequestID 399bee76ad78574297166e3ef0b8cbd2

import { ConcreteRequest } from 'relay-runtime';
import { FragmentRefs } from "relay-runtime";
export type PaginationDemoQuery$variables = Record<PropertyKey, never>;
export type PaginationDemoQuery$data = {
  readonly " $fragmentSpreads": FragmentRefs<"PaginationList_query">;
};
export type PaginationDemoQuery = {
  response: PaginationDemoQuery$data;
  variables: PaginationDemoQuery$variables;
};

const node: ConcreteRequest = (function(){
var v0 = [
  {
    "kind": "Literal",
    "name": "first",
    "value": 3
  }
],
v1 = {
  "alias": null,
  "args": null,
  "kind": "ScalarField",
  "name": "id",
  "storageKey": null
};
return {
  "fragment": {
    "argumentDefinitions": [],
    "kind": "Fragment",
    "metadata": null,
    "name": "PaginationDemoQuery",
    "selections": [
      {
        "args": null,
        "kind": "FragmentSpread",
        "name": "PaginationList_query"
      }
    ],
    "type": "Query",
    "abstractKey": null
  },
  "kind": "Request",
  "operation": {
    "argumentDefinitions": [],
    "kind": "Operation",
    "name": "PaginationDemoQuery",
    "selections": [
      {
        "alias": null,
        "args": (v0/*:: as any*/),
        "concreteType": "PostConnection",
        "kind": "LinkedField",
        "name": "feed",
        "plural": false,
        "selections": [
          {
            "alias": null,
            "args": null,
            "kind": "ScalarField",
            "name": "totalCount",
            "storageKey": null
          },
          {
            "alias": null,
            "args": null,
            "concreteType": "PostEdge",
            "kind": "LinkedField",
            "name": "edges",
            "plural": true,
            "selections": [
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "cursor",
                "storageKey": null
              },
              {
                "alias": null,
                "args": null,
                "concreteType": "Post",
                "kind": "LinkedField",
                "name": "node",
                "plural": false,
                "selections": [
                  (v1/*:: as any*/),
                  {
                    "alias": null,
                    "args": null,
                    "kind": "ScalarField",
                    "name": "title",
                    "storageKey": null
                  },
                  {
                    "alias": null,
                    "args": null,
                    "kind": "ScalarField",
                    "name": "likeCount",
                    "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
                      },
                      (v1/*:: as any*/)
                    ],
                    "storageKey": null
                  },
                  {
                    "alias": null,
                    "args": null,
                    "kind": "ScalarField",
                    "name": "__typename",
                    "storageKey": null
                  }
                ],
                "storageKey": null
              }
            ],
            "storageKey": null
          },
          {
            "alias": null,
            "args": null,
            "concreteType": "PageInfo",
            "kind": "LinkedField",
            "name": "pageInfo",
            "plural": false,
            "selections": [
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "endCursor",
                "storageKey": null
              },
              {
                "alias": null,
                "args": null,
                "kind": "ScalarField",
                "name": "hasNextPage",
                "storageKey": null
              }
            ],
            "storageKey": null
          }
        ],
        "storageKey": "feed(first:3)"
      },
      {
        "alias": null,
        "args": (v0/*:: as any*/),
        "filters": null,
        "handle": "connection",
        "key": "PaginationList_feed",
        "kind": "LinkedHandle",
        "name": "feed"
      }
    ]
  },
  "params": {
    "id": "399bee76ad78574297166e3ef0b8cbd2",
    "metadata": {},
    "name": "PaginationDemoQuery",
    "operationKind": "query",
    "text": null
  }
};
})();

(node as any).hash = "94a95e248fb268f96a44cf7efedbc818";

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.