Add a filter middleware

lib/format.js

@@ -0,0 +1,26 @@
+
+var mime = require('mime'),
+    path = require('path');
+
+module.exports = function(app, defaultType) {
+    return function(env, callback) {
+        var extname, format, pathInfo;
+        pathInfo     = env.pathInfo;
+        extname      = path.extname(pathInfo);
+        format       = extname ? mime.lookup(extname) : null;
+        env.format   = format;
+
+        // Modify env.pathInfo for downstream apps
+        if (extname) {
+            env.pathInfo = pathInfo.replace(new RegExp("" + extname + "$"), "");
+        }
+
+
+        return app(env, function(status, headers, body) {
+            // Reset env.pathInfo for upstream apps.
+            env.pathInfo = pathInfo;
+
+            return callback(status, headers, body);
+        });
+    };
+};

lib/index.js

@@ -326,6 +326,7 @@ var propPaths = {
     "contentType": "contenttype",
     "directory": "directory",
     "file": "file",
+    "format": "format",
     "gzip": "gzip",
     "jsonp": "jsonp",
     "lint": "lint",

test/format_test.js

@@ -0,0 +1,50 @@
+var assert = require("assert"),
+    vows = require("vows"),
+    strata = require("./../lib"),
+    mock = strata.mock,
+    format = strata.format;
+
+vows.describe("format").addBatch({
+    "A format middleware": {
+        topic: function () {
+            var app = function (env, callback) {
+                callback(200, {
+                    "Content-Type": "text/plain",
+                    "X-PathInfo": env.pathInfo,
+                    "X-Format": env.format
+                }, "");
+            }
+
+            app = format(app);
+
+            return app;
+        },
+        "when /abc is requested": {
+            topic: function (app) {
+                mock.request("/abc", app, this.callback);
+            },
+            "should format properly": function (err, status, headers, body) {
+                assert.equal(headers["X-Format"], null);
+                assert.equal(headers["X-PathInfo"], "/abc");
+            }
+        },
+        "when /abc.json is requested": {
+            topic: function (app) {
+                mock.request("/abc.json", app, this.callback);
+            },
+            "should format properly": function (err, status, headers, body) {
+                assert.equal(headers["X-Format"], "application/json");
+                assert.equal(headers["X-PathInfo"], "/abc");
+            }
+        },
+        "when /abc.xml is requested": {
+            topic: function (app) {
+                mock.request("/abc.xml", app, this.callback);
+            },
+            "should format properly": function (err, status, headers, body) {
+                assert.equal(headers["X-Format"], "application/xml");
+                assert.equal(headers["X-PathInfo"], "/abc");
+            }
+        }
+    }
+}).export(module);