feat: allow ttl to be defined based on the response

README.md

@@ -531,10 +531,13 @@ You can override the request id used by this property.
 
 ### request.cache.ttl
 
-The time that the request will remain in cache. Some custom storage implementations may
-not respect 100% the time.
+The time until the cached value is expired in milliseconds.
 
-When using `interpretHeader`, this value is ignored.
+If a function is used, it will receive the complete response and waits to return a TTL
+value
+
+When using `interpretHeader: true`, this value will only be used if the interpreter can't
+determine their TTL value to override this
 
 ### request.cache.interpretHeader
 

src/cache/cache.ts

@@ -11,14 +11,14 @@ export type CacheProperties = {
   /**
    * The time until the cached value is expired in milliseconds.
    *
+   * If a function is used, it will receive the complete response and waits to return a TTL value
+   *
    * When using `interpretHeader: true`, this value will only be used if the interpreter
    * can't determine their TTL value to override this
    *
-   * **Note**: a custom storage implementation may not respect this.
-   *
    * @default 1000 * 60 * 5 // 5 Minutes
    */
-  ttl: number;
+  ttl: number | (<R, D>(response: CacheAxiosResponse<R, D>) => number | Promise<number>);
 
   /**
    * If this interceptor should configure the cache from the request cache header When

src/interceptors/response.ts

@@ -88,6 +88,10 @@ export class CacheResponseInterceptor<R, D>
 
     const data = setupCacheData(response, cache.data);
 
+    if (typeof ttl === 'function') {
+      ttl = await ttl(response);
+    }
+
     const newCache: CachedStorageValue = {
       state: 'cached',
       ttl,

test/interceptors/response.test.ts

@@ -1,5 +1,5 @@
 import { Header } from '../../src/util/headers';
-import { mockAxios } from '../mocks/axios';
+import { mockAxios, XMockRandom } from '../mocks/axios';
 
 describe('test request interceptor', () => {
   it('tests cache predicate integration', async () => {
@@ -79,4 +79,74 @@ describe('test request interceptor', () => {
     expect(cache.state).toBe('cached');
     expect(cache.ttl).toBe(defaultTtl);
   });
+
+  it('tests ttl with functions', async () => {
+    const axios = mockAxios();
+    const id = 'my-id';
+
+    // first request (cached by tll)
+
+    await axios.get('url', {
+      id,
+      cache: {
+        ttl: (resp) => {
+          expect(resp.cached).toBe(false);
+          expect(resp.config).toBeDefined();
+          expect(resp.headers[XMockRandom]).not.toBeNaN();
+          expect(resp.status).toBe(200);
+          expect(resp.statusText).toBe('200 OK');
+          expect(resp.data).toBeTruthy();
+
+          return 100;
+        }
+      }
+    });
+
+    const cache1 = await axios.storage.get(id);
+    expect(cache1.state).toBe('cached');
+    expect(cache1.ttl).toBe(100);
+
+    // Second request (cached by ttl)
+
+    const ttl = jest.fn().mockReturnValue(200);
+
+    await axios.get('url', {
+      id,
+      cache: { ttl }
+    });
+
+    const cache2 = await axios.storage.get(id);
+    expect(cache2.state).toBe('cached');
+    expect(cache2.ttl).toBe(100);
+
+    expect(ttl).not.toHaveBeenCalled();
+
+    // Force invalidation
+    await axios.storage.remove(id);
+  });
+
+  it('tests async ttl function', async () => {
+    const axios = mockAxios();
+
+    // A lot of promises and callbacks
+    const { id } = await axios.get('url', {
+      cache: {
+        ttl: async () => {
+          await 0;
+
+          return new Promise((res) => {
+            setTimeout(() => {
+              process.nextTick(() => {
+                res(173);
+              });
+            }, 50);
+          });
+        }
+      }
+    });
+
+    const cache = await axios.storage.get(id);
+    expect(cache.state).toBe('cached');
+    expect(cache.ttl).toBe(173);
+  });
 });