Initial commit

Author: christophermaier

.gitignore

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+pom.xml
+*jar
+/lib/
+/classes/
+.lein-deps-sum

README.md

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+# ring-request-diff
+
+See how Ring middleware changes a request.
+
+## Usage
+
+`ring-request-diff` wraps other Ring middleware, allowing you to monitor how that middleware changes the values of specific keys of a request map.
+
+    (-> #'handler
+        ring.middleware.nested-params/wrap-nested-params
+        (wrap-request-diff [:params] ring.middleware.keyword-params/wrap-keyword-params)
+        ring.middleware.params/wrap-params)
+
+It takes a vector of request keys (keyword or string form; either one works), the middleware function it wraps, and any additional arguments required for that wrapped function.
+
+The request is run through the wrapped middleware function.  Whenever the value stored under one of the watched keys is changed, a diff of the value (pre- vs. post-middleware) is printed to `*out*`.  The processed request is then sent down the rest of the middleware chain.
+
+This comes in handy for debugging complex stacks of middleware, allowing you to easily see exactly what each function is doing, making sure the ordering of middleware is correct, etc.
+
+## Install
+
+Add the following dependency to your `project.clj` file:
+
+    [ring-request-diff "0.1.0"]
+
+## License
+
+Copyright (C) 2011 Christopher Maier
+
+Distributed under the Eclipse Public License, the same as Clojure.

project.clj

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+(defproject ring-request-diff "0.1.0"
+  :description "Ring middleware to show how other middleware changes a request body"
+  :dependencies [[org.clojure/clojure "1.2.0"]
+                 [org.clojure/clojure-contrib "1.2.0"]
+                 [difform "1.1.1"]])

src/ring/middleware/request_diff.clj

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+(ns ring.middleware.request-diff
+  "See how middleware changes a Ring request body"
+  (:use (com.georgejahad (difform :only [difform]))))
+
+(defn wrap-request-diff
+  "Debug other middleware by wrapping them and printing out what they change in a Ring request body.
+
+  `keys` is a sequence of request keys (string or keyword) that you want to monitor changes in.
+  `middleware-fn` is the middleware function being wrapped
+  `args` (optional) are for `middleware-fn`, and will be passed through to it."
+  [handler keys middleware-fn & args]
+  (letfn [(omni-get [m k] ;; handle either keyword or string parameter names
+            (or (get m (keyword k))
+                (get m (name k))))]
+    (fn [req]
+      (let [processed-req ((apply middleware-fn identity args) req)]
+        (doseq [k keys]
+          (let [old-part (omni-get req k)
+                new-part (omni-get processed-req k)
+                uri (omni-get req :uri)]
+            (if-not (= old-part new-part)
+              (do (println "Diff" uri "for" k "with" middleware-fn)
+                  (difform old-part new-part))
+              (println "No difference on" uri "for" k "with" middleware-fn))))
+        (handler processed-req)))))