Added response "header" event allowing augmentation

this will be used in the session middleware, and could be used elsewhere. Ideally Node would provide a hook for us...
senchalabs · Jul 20, 2011 · 1ce13cb · 1ce13cb
1 parent 04af2c6
commit 1ce13cb
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Showing 2 changed files with 76 additions and 29 deletions.
diff --git a/lib/patch.js b/lib/patch.js
@@ -16,36 +16,52 @@ var http = require('http')
 
 var setHeader = res.setHeader;
 
+// original _renderHeaders()
 
-if (!res._hasConnectPatch) {
+var _renderHeaders = res._renderHeaders;
-
+
-  /**
+if (res._hasConnectPatch) return;
-   * Set header `field` to `val`, special-casing
+
-   * the `Set-Cookie` field for multiple support.
+/**
-   *
+ * Set header `field` to `val`, special-casing
-   * @param {String} field
+ * the `Set-Cookie` field for multiple support.
-   * @param {String} val
+ *
-   * @api public
+ * @param {String} field
-   */
+ * @param {String} val
-
+ * @api public
-  res.setHeader = function(field, val){
+ */
-    var key = field.toLowerCase()
+
-      , prev;
+res.setHeader = function(field, val){
-
+  var key = field.toLowerCase()
-    // special-case Set-Cookie
+    , prev;
-    if (this._headers && 'set-cookie' == key) {
+
-      if (prev = this.getHeader(field)) {
+  // special-case Set-Cookie
-        val = Array.isArray(prev)
+  if (this._headers && 'set-cookie' == key) {
-          ? prev.concat(val)
+    if (prev = this.getHeader(field)) {
-          : [prev, val];
+      val = Array.isArray(prev)
-      }
+        ? prev.concat(val)
-    // charset
+        : [prev, val];
-    } else if ('content-type' == key && this.charset) {
-      val += '; charset=' + this.charset;
     }
+  // charset
+  } else if ('content-type' == key && this.charset) {
+    val += '; charset=' + this.charset;
+  }
+
+  return setHeader.call(this, field, val);
+};
+
+/**
+ * Proxy `res.end()` to expose a 'header' event,
+ * allowing arbitrary augmentation before the header
+ * fields are written to the socket.
+ *
+ * NOTE: this _only_ supports node's progressive header
+ * field API aka `res.setHeader()`.
+ */
 
-    return setHeader.call(this, field, val);
+res._renderHeaders = function(){
-  };
+  this.emit('header');
+  return _renderHeaders.call(this);
+};
 
-  res._hasConnectPatch = true;
+res._hasConnectPatch = true;
-}
diff --git a/test/connect.test.js b/test/connect.test.js
@@ -52,6 +52,37 @@ module.exports = {
       { body: 'blog', status: 200 });
   },
 
+  'test "header" event': function(){
+    var app = connect.createServer();
+
+    app.use(function(req, res, next){
+      res.on('header', function(){
+        if (req.headers['x-foo']) {
+          res.setHeader('X-Bar', 'baz');
+        }
+      });
+
+      next();
+    });
+
+    app.use(function(req, res){
+      // FIXME: this fails if you do not have any res._headers
+      res.setHeader('Content-Length', 5);
+      res.end('hello');
+    });
+
+    assert.response(app,
+      { url: '/' },
+      function(res){
+        res.headers.should.not.have.property('x-foo');
+        res.headers.should.not.have.property('x-bar');
+      });
+
+    assert.response(app,
+      { url: '/', headers: { 'X-Foo': 'bar' }},
+      { body: 'hello', headers: { 'X-Bar': 'baz' }});
+  },
+
   'test path matching': function(){
     var n = 0
       , app = connect.createServer();