Avoid dereferencing before caching (#2793)

Author: gregberge

.changeset/khaki-zebras-deliver.md

@@ -0,0 +1,6 @@
+---
+'@gitbook/react-openapi': patch
+'gitbook': patch
+---
+
+Do not dereference before caching OpenAPI spec.

packages/gitbook/src/lib/openapi.ts

@@ -49,7 +49,7 @@ export async function fetchOpenAPIBlock(
 
 const fetcher: OpenAPIFetcher = {
     fetch: cache({
-        name: 'openapi.fetch.v3',
+        name: 'openapi.fetch.v4',
         get: async (url: string, options: CacheFunctionOptions) => {
             // Wrap the raw string to prevent invalid URLs from being passed to fetch.
             // This can happen if the URL has whitespace, which is currently handled differently by Cloudflare's implementation of fetch:

packages/react-openapi/src/fetchOpenAPIOperation.ts

@@ -1,9 +1,9 @@
 import { toJSON, fromJSON } from 'flatted';
 
-import { OpenAPICustomSpecProperties } from './parser';
-import { OpenAPIV3, OpenAPIV3_1 } from '@scalar/openapi-types';
+import { OpenAPICustomSpecProperties, OpenAPIParseError } from './parser';
+import { OpenAPI, OpenAPIV3, OpenAPIV3_1 } from '@scalar/openapi-types';
 import { noReference } from './utils';
-import { parseDescriptions } from './parser/markdown';
+import { dereference } from '@scalar/openapi-parser';
 
 export interface OpenAPIFetcher {
     /**
@@ -44,7 +44,8 @@ export async function fetchOpenAPIOperation(
     },
     fetcher: OpenAPIFetcher,
 ): Promise<OpenAPIOperationData | null> {
-    const schema = await fetcher.fetch(input.url);
+    const refSchema = await fetcher.fetch(input.url);
+    const schema = await memoDereferenceSchema(refSchema, input.url);
 
     let operation = getOperationByPathAndMethod(schema, input.path, input.method);
 
@@ -89,6 +90,38 @@ export async function fetchOpenAPIOperation(
     };
 }
 
+const dereferenceSchemaCache = new WeakMap<OpenAPI.Document, Promise<OpenAPI.Document>>();
+
+/**
+ * Memoized version of `dereferenceSchema`.
+ */
+function memoDereferenceSchema<T extends OpenAPI.Document>(schema: T, url: string): Promise<T> {
+    if (dereferenceSchemaCache.has(schema)) {
+        return dereferenceSchemaCache.get(schema) as Promise<T>;
+    }
+
+    const promise = dereferenceSchema(schema, url);
+    dereferenceSchemaCache.set(schema, promise);
+    return promise;
+}
+
+/**
+ * Dereference an OpenAPI schema.
+ */
+async function dereferenceSchema<T extends OpenAPI.Document>(schema: T, url: string): Promise<T> {
+    const derefResult = await dereference(schema);
+
+    if (!derefResult.schema) {
+        throw new OpenAPIParseError(
+            'Failed to dereference OpenAPI document',
+            url,
+            'failed-dereference',
+        );
+    }
+
+    return derefResult.schema as T;
+}
+
 /**
  * Get a path object from its path.
  */

packages/react-openapi/src/parser/error.ts

@@ -4,7 +4,7 @@ export class OpenAPIParseError extends Error {
     constructor(
         message: string,
         public readonly url: string,
-        public readonly code?: 'invalid-spec' | 'v2-spec',
+        public readonly code?: 'invalid-spec' | 'v2-spec' | 'failed-dereference',
     ) {
         super(message);
     }

packages/react-openapi/src/parser/fixtures/spec-example.json

@@ -0,0 +1,14 @@
+import { expect, it } from 'bun:test';
+import { readFile } from 'node:fs/promises';
+import { parseOpenAPI } from '.';
+
+it('should parse and not give a recursive structure', async () => {
+    const schema = await parseOpenAPI({
+        value: await readFile(new URL('./fixtures/spec-example.json', import.meta.url), 'utf-8'),
+        url: 'https://example.com',
+        parseMarkdown: async (input) => input,
+    });
+
+    JSON.stringify(schema);
+    expect(schema.openapi).toBe('3.0.0');
+});

packages/react-openapi/src/parser/index.test.ts

@@ -15,8 +15,6 @@ export function traverse(
         return specification;
     }
 
-    seen.add(specification);
-
     for (const [key, value] of Object.entries(specification)) {
         const currentPath = [...path, key];
         if (Array.isArray(value)) {

packages/react-openapi/src/parser/traverse.ts

@@ -1,5 +1,5 @@
 import { OpenAPICustomSpecProperties } from './types';
-import { AnyApiDefinitionFormat, dereference } from '@scalar/openapi-parser';
+import { AnyApiDefinitionFormat, validate } from '@scalar/openapi-parser';
 import { OpenAPIV3, OpenAPIV3_1 } from '@scalar/openapi-types';
 import { OpenAPIParseError } from './error';
 import { parseDescriptions } from './markdown';
@@ -18,27 +18,27 @@ export async function parseOpenAPIV3(input: {
     | OpenAPIV3_1.Document<OpenAPICustomSpecProperties>
 > {
     const { value, url } = input;
-    const result = await dereference(value);
+    const result = await validate(value);
 
     // Spec is invalid, we stop here.
-    if (!result.schema) {
+    if (!result.specification) {
         throw new OpenAPIParseError('Invalid OpenAPI document', url, 'invalid-spec');
     }
 
     if (result.version === '2.0') {
         throw new OpenAPIParseError('Only OpenAPI v3 is supported', url, 'v2-spec');
     }
 
-    const schema = await parseDescriptions({
-        specification: result.schema,
+    const specification = await parseDescriptions({
+        specification: result.specification,
         parseMarkdown: input.parseMarkdown,
     });
 
     switch (result.version) {
         case '3.0':
-            return schema as OpenAPIV3.Document<OpenAPICustomSpecProperties>;
+            return specification as OpenAPIV3.Document<OpenAPICustomSpecProperties>;
         case '3.1':
         default:
-            return schema as OpenAPIV3_1.Document<OpenAPICustomSpecProperties>;
+            return specification as OpenAPIV3_1.Document<OpenAPICustomSpecProperties>;
     }
 }