fix: implemented-parsing-next-link-from-header

Author: Zaimwa9

sdk/index.ts

@@ -329,7 +329,7 @@ export class Flagsmith {
         url: string,
         method: string,
         body?: { [key: string]: any }
-    ): Promise<any> {
+    ): Promise<{ response: Response; data: any }> {
         const headers: { [key: string]: any } = { 'Content-Type': 'application/json' };
         if (this.environmentKey) {
             headers['X-Environment-Key'] = this.environmentKey as string;
@@ -361,7 +361,7 @@ export class Flagsmith {
             );
         }
 
-        return data.json();
+        return { response: data, data: await data.json() };
     }
 
     /**
@@ -395,25 +395,41 @@ export class Flagsmith {
         const documents: any[] = [];
         let url = this.environmentUrl;
         let loggedWarning = false;
+
         while (true) {
-            if (!loggedWarning) {
-                const elapsedMs = Date.now() - startTime;
-                if (elapsedMs > this.environmentRefreshIntervalSeconds * 1000) {
-                    this.logger.warn(
-                        `Environment document retrieval exceeded the polling interval of ${this.environmentRefreshIntervalSeconds} seconds.`
-                    );
-                    loggedWarning = true;
+            try {
+                if (!loggedWarning) {
+                    const elapsedMs = Date.now() - startTime;
+                    if (elapsedMs > this.environmentRefreshIntervalSeconds * 1000) {
+                        this.logger.warn(
+                            `Environment document retrieval exceeded the polling interval of ${this.environmentRefreshIntervalSeconds} seconds.`
+                        );
+                        loggedWarning = true;
+                    }
                 }
-            }
 
-            const response = await this.getJSONResponse(url, 'GET');
-            documents.push(response);
+                const { response, data } = await this.getJSONResponse(url, 'GET');
+
+                documents.push(data);
 
-            if (response.links && response.links.next && response.links.next.url) {
-                url = response.links.next.url;
-                continue;
+                const linkHeader = response.headers.get('link');
+                if (linkHeader) {
+                    const nextMatch = linkHeader.match(/<([^>]+)>;\s*rel="next"/);
+
+                    if (nextMatch) {
+                        const relativeUrl = decodeURIComponent(nextMatch[1]);
+                        url = new URL(relativeUrl, this.apiUrl).href;
+
+                        continue;
+                    }
+                }
+                break;
+            } catch (error) {
+                if (error instanceof FlagsmithAPIError && error.message.includes('502')) {
+                    break;
+                }
+                throw error;
             }
-            break;
         }
 
         // Compile the document
@@ -473,7 +489,7 @@ export class Flagsmith {
         if (!this.environmentFlagsUrl) {
             throw new Error('`apiUrl` argument is missing or invalid.');
         }
-        const apiFlags = await this.getJSONResponse(this.environmentFlagsUrl, 'GET');
+        const { data: apiFlags } = await this.getJSONResponse(this.environmentFlagsUrl, 'GET');
         const flags = Flags.fromAPIFlags({
             apiFlags: apiFlags,
             analyticsProcessor: this.analyticsProcessor,
@@ -494,7 +510,7 @@ export class Flagsmith {
             throw new Error('`apiUrl` argument is missing or invalid.');
         }
         const data = generateIdentitiesData(identifier, traits, transient);
-        const jsonResponse = await this.getJSONResponse(this.identitiesUrl, 'POST', data);
+        const { data: jsonResponse } = await this.getJSONResponse(this.identitiesUrl, 'POST', data);
         const flags = Flags.fromAPIFlags({
             apiFlags: jsonResponse['flags'],
             analyticsProcessor: this.analyticsProcessor,

tests/engine/unit/engine.test.ts

@@ -12,7 +12,6 @@ import {
     environmentWithSegmentOverride,
     feature1,
     getEnvironmentFeatureStateForFeature,
-    getEnvironmentFeatureStateForFeatureByName,
     identity,
     identityInSegment,
     segmentConditionProperty,

tests/sdk/flagsmith.test.ts

@@ -48,23 +48,29 @@ test('test_update_environment_handles_paginated_document', async () => {
             const env = headers['X-Environment-Key'];
 
             if (url.includes('/environment-document')) {
-                if (env.startsWith('ser.')) {
-                    const page = pages[callCount];
-                    if (page) {
-                        callCount++;
-                        return Promise.resolve(new Response(JSON.stringify(page), { status: 200 }));
+                const page = pages[callCount];
+                if (page) {
+                    callCount++;
+
+                    const responseHeaders: Record<string, string> = {};
+
+                    if (page.nextUrl) {
+                        responseHeaders['Link'] = `<${page.nextUrl}>; rel="next"`;
                     }
+
+                    return Promise.resolve(
+                        new Response(JSON.stringify(page), {
+                            status: 200,
+                            headers: responseHeaders
+                        })
+                    );
                 }
-                return Promise.resolve(
-                    new Response('environment-document called without a server-side key', {
-                        status: 401
-                    })
-                );
             }
             return Promise.resolve(new Response('unknown url ' + url, { status: 404 }));
         });
     };
 
+    // Added a field "nextUrl" to indicate the mock there is a next page
     const pages = [
         {
             id: 1,
@@ -118,7 +124,7 @@ test('test_update_environment_handles_paginated_document', async () => {
                 }
             ],
             identity_overrides: [{ id: 1, identifier: 'user1' }],
-            links: { next: { url: '/api/v1/environment-document?page=2' } }
+            nextUrl: '/api/v1/environment-document?page=2'
         },
         {
             id: 1,
@@ -138,7 +144,7 @@ test('test_update_environment_handles_paginated_document', async () => {
             },
             feature_states: [],
             identity_overrides: [{ id: 2, identifier: 'user2' }],
-            links: { next: { url: '/api/v1/environment-document?page=3' } }
+            nextUrl: '/api/v1/environment-document?page=3'
         },
         {
             id: 1,
@@ -158,7 +164,7 @@ test('test_update_environment_handles_paginated_document', async () => {
             },
             feature_states: [],
             identity_overrides: [{ id: 2, identifier: 'user3' }],
-            links: null
+            nextUrl: null
         }
     ];