language: fallback scenario from invalid querystring to valid header

middleware/requestLanguage.js

@@ -1,4 +1,6 @@
 
+const _ = require('lodash');
+
 /**
   this middleware is responsible for negotiating HTTP locales for incoming
   browser requests by reading the querystring param 'lang' or 'Accept-Language' request headers.
@@ -53,19 +55,46 @@ const allLocales = new locale.Locales( Object.keys( language ) );
 // return the middleware
 module.exports = function middleware( req, res, next ){
 
-  // input language, either from query param or header
-  var input = ( req.query && req.query.lang ) || ( req.headers && req.headers['accept-language'] );
+  // init an object to store clean (sanitized) input parameters if not initialized
+  req.clean = req.clean || {};
+
+  // init warnings array if not initialized
+  req.warnings = req.warnings || [];
+
+  // set defaults
+  var lang = language.en;
+  var isDefault = true;
+  var locales, best;
+
+  // input language via query param
+  if( isDefault && req.query && req.query.lang ){
+    locales = new locale.Locales( req.query.lang );
+    best = locales.best( allLocales );
+    if( best.defaulted ){
+      req.warnings.push( 'invalid language provided via querystring' );
+    } else {
+      lang = language[ best.language ];
+      isDefault = false;
+    }
+  }
 
-  // parse request & choose best locale
-  var locales = new locale.Locales( input || '' );
-  var best = locales.best( allLocales );
+  // input language via request headers
+  if( isDefault && req.headers && req.headers['accept-language'] ){
+    locales = new locale.Locales( req.headers['accept-language'] );
+    best = locales.best( allLocales );
+    if( best.defaulted ){
+      req.warnings.push( 'invalid language provided via header' );
+    } else {
+      lang = language[ best.language ];
+      isDefault = false;
+    }
+  }
 
   // set $req.language property
-  req.language = language[ best.language ] || language.en;
-  req.language.defaulted = best.defaulted;
+  req.language = _.clone( lang );
+  req.language.defaulted = isDefault;
 
   // set $req.clean property in order to print language info in response header
-  req.clean = req.clean || {};
   req.clean.lang = {
     name: req.language.name,
     iso6391: req.language.iso6391,

test/unit/middleware/requestLanguage.js

@@ -28,6 +28,33 @@ module.exports.tests.defaults = function(test, common) {
         name: req.language.name
       }, '$req.clean.lang set' );
 
+      t.deepEqual( req.warnings, []);
+
+      t.end();
+    });
+  });
+  test('both querystring & header invalid', function(t) {
+
+    var req = {
+      headers: { 'accept-language': 'foobar' },
+      query: { 'lang': 'foobar' }
+    };
+
+    middleware(req, {}, function () {
+      t.deepEqual( req.language, DEFAULTS, '$req.language set' );
+
+      t.deepEqual( req.clean.lang, {
+        defaulted: req.language.defaulted,
+        iso6391: req.language.iso6391,
+        iso6393: req.language.iso6393,
+        name: req.language.name
+      }, '$req.clean.lang set' );
+
+      t.deepEqual( req.warnings, [
+        'invalid language provided via querystring',
+        'invalid language provided via header'
+      ]);
+
       t.end();
     });
   });
@@ -50,6 +77,10 @@ module.exports.tests.invalid = function(test, common) {
         name: req.language.name
       }, '$req.clean.lang set' );
 
+      t.deepEqual( req.warnings, [
+        'invalid language provided via header'
+      ]);
+
       t.end();
     });
   });
@@ -69,6 +100,10 @@ module.exports.tests.invalid = function(test, common) {
         name: req.language.name
       }, '$req.clean.lang set' );
 
+      t.deepEqual( req.warnings, [
+        'invalid language provided via querystring'
+      ]);
+
       t.end();
     });
   });
@@ -102,6 +137,8 @@ module.exports.tests.valid = function(test, common) {
         name: req.language.name
       }, '$req.clean.lang set' );
 
+      t.deepEqual( req.warnings, []);
+
       t.end();
     });
   });
@@ -132,6 +169,8 @@ module.exports.tests.valid = function(test, common) {
         name: req.language.name
       }, '$req.clean.lang set' );
 
+      t.deepEqual( req.warnings, []);
+
       t.end();
     });
   });
@@ -155,6 +194,16 @@ module.exports.tests.valid = function(test, common) {
 
     middleware(req, {}, function () {
       t.deepEqual( req.language, expected, '$req.language set' );
+
+      t.deepEqual( req.clean.lang, {
+        defaulted: req.language.defaulted,
+        iso6391: req.language.iso6391,
+        iso6393: req.language.iso6393,
+        name: req.language.name
+      }, '$req.clean.lang set' );
+
+      t.deepEqual( req.warnings, []);
+
       t.end();
     });
   });
@@ -177,6 +226,16 @@ module.exports.tests.valid = function(test, common) {
 
     middleware(req, {}, function () {
       t.deepEqual( req.language, expected, '$req.language set' );
+
+      t.deepEqual( req.clean.lang, {
+        defaulted: req.language.defaulted,
+        iso6391: req.language.iso6391,
+        iso6393: req.language.iso6393,
+        name: req.language.name
+      }, '$req.clean.lang set' );
+
+      t.deepEqual( req.warnings, []);
+
       t.end();
     });
   });
@@ -211,6 +270,43 @@ module.exports.tests.precedence = function(test, common) {
         name: req.language.name
       }, '$req.clean.lang set' );
 
+      t.deepEqual( req.warnings, []);
+
+      t.end();
+    });
+  });
+  test('precedence: invalid querystring but valid header', function(t) {
+
+    var req = {
+      headers: { 'accept-language': 'fr' },
+      query: { 'lang': 'foobar' }
+    };
+
+    var expected = {
+      defaulted: false,
+      iso6391: 'fr',
+      iso6392B: 'fre',
+      iso6392T: 'fra',
+      iso6393: 'fra',
+      name: 'French',
+      scope: 'individual',
+      type: 'living'
+    };
+
+    middleware(req, {}, function () {
+      t.deepEqual( req.language, expected, '$req.language set' );
+
+      t.deepEqual( req.clean.lang, {
+        defaulted: req.language.defaulted,
+        iso6391: req.language.iso6391,
+        iso6393: req.language.iso6393,
+        name: req.language.name
+      }, '$req.clean.lang set' );
+
+      t.deepEqual( req.warnings, [
+        'invalid language provided via querystring'
+      ]);
+
       t.end();
     });
   });