Allow requests to force cache to revalidate

README.md

@@ -246,6 +246,8 @@ routes to be cached from your public client, but NOT cached when from the admin
 is achieved by sending a `"x-apicache-bypass": true` header along with the requst from the admin.
 The presence of this header flag will bypass the cache, ensuring you aren't looking at stale data.
 
+Additionally, you may want to bypass loading stale content for a request while still updating the cache with fresh content. To achieve this, include a `"x-apicache-bypass": true` header with the request.
+
 ## Contributors
 
 Special thanks to all those that use this library and report issues, but especially to the following active users that have helped add to the core functionality!

src/apicache.js

@@ -639,9 +639,11 @@ function ApiCache() {
       // attempt cache hit
       var redis = opt.redisClient
       var cached = !redis ? memCache.getValue(key) : null
+      // skip cache load when x-apicache-revalidate is present
+      var revalidate = req.headers['x-apicache-revalidate']
 
       // send if cache hit from memory-cache
-      if (cached) {
+      if (!revalidate && cached) {
         var elapsed = new Date() - req.apicacheTimer
         debug('sending cached (memory-cache) version of', key, logDuration(elapsed))
 
@@ -650,7 +652,7 @@ function ApiCache() {
       }
 
       // send if cache hit from redis
-      if (redis && redis.connected) {
+      if (!revalidate && redis && redis.connected) {
         try {
           redis.hgetall(key, function(err, obj) {
             if (!err && obj && obj.response) {

test/apicache_test.js

@@ -549,6 +549,31 @@ describe('.middleware {MIDDLEWARE}', function() {
           })
       })
 
+      it('revalidates cache when using header "x-apicache-revalidate"', function(done) {
+        var app = mockAPI.create('10 seconds')
+
+        request(app)
+          .get('/api/movies')
+          .expect(200, movies)
+          .expect('Cache-Control', 'max-age=10')
+          .then(assertNumRequestsProcessed(app, 1))
+          .then(function() {
+            setTimeout(function() {
+              return request(app)
+                .get('/api/movies')
+                .set('x-apicache-revalidate', true)
+                .expect(200, movies)
+                .expect('Cache-Control', 'max-age=10')
+                .then(function(res) {
+                  expect(res.headers['apicache-store']).to.be.undefined
+                  expect(res.headers['apicache-version']).to.be.undefined
+                  expect(app.requestsProcessed).to.equal(2)
+                  done()
+                })
+            }, 500)
+          })
+      })
+
       it('does not cache header in headerBlacklist', function() {
         var app = mockAPI.create('10 seconds', { headerBlacklist: ['x-blacklisted'] })