apply default serializer.req before using configured serializer.req

index.js

@@ -14,7 +14,14 @@ const levelTags = {
 
 async function register (server, options) {
   options.serializers = options.serializers || {}
-  options.serializers.req = options.serializers.req || asReqValue
+  if (options.serializers.req) {
+    const origReqSerializer = options.serializers.req
+    options.serializers.req = (req) => {
+      return origReqSerializer(asReqValue(req))
+    }
+  } else if (options.serializers.req !== null) {
+    options.serializers.req = asReqValue
+  }
   options.serializers.res = options.serializers.res || pino.stdSerializers.res
   options.serializers.err = options.serializers.err || pino.stdSerializers.err
 

test.js

@@ -742,7 +742,37 @@ experiment('logging with overridden serializer', () => {
       options: {
         instance: logger,
         serializers: {
-          req: (req) => ({ uri: req.raw.req.url })
+          req: (req) => ({ uri: req.url })
+        }
+      }
+    }
+
+    await server.register(plugin)
+    await server.inject({
+      method: 'GET',
+      url: '/'
+    })
+    await finish
+  })
+
+  test('with req serializer set to null', async () => {
+    const server = getServer()
+    let done
+    const finish = new Promise(function (resolve, reject) {
+      done = resolve
+    })
+    const stream = sink((data) => {
+      expect(data.req.uri).to.not.equal('/')
+      expect(data.req.raw).to.be.an.object()
+      done()
+    })
+    const logger = require('pino')(stream)
+    const plugin = {
+      plugin: Pino,
+      options: {
+        instance: logger,
+        serializers: {
+          req: null
         }
       }
     }