feat(docs/tutorials): setting cookies on GET requests

[mjholub]

This was something I struggled with a little before I had my 'aha' moment with the hidden form, so I figured out that writing such tutorial could be useful for other biff users.
Please note that the implementation I've used in my actual project is somewhat less context free with a little bit more hardcoding, since I've only needed to set one cookie so far hehe.

[jacobobryant]

Hey, thanks for taking the time to write this up! There's a simpler way to do this, though. Request handlers are allowed to return Rum as a convenience, but you can still return a regular ring response map if you want. For example, I modified the landing page in the starter app so it sets a cookie when you request the page (via get request):

diff --git a/starter/src/com/example/home.clj b/starter/src/com/example/home.clj
index c19235d..ec1a319 100644
--- a/starter/src/com/example/home.clj
+++ b/starter/src/com/example/home.clj
@@ -12,7 +12,7 @@
    "Until you add API keys for MailerSend and reCAPTCHA, we'll print your sign-up "
    "link to the console. See config.edn."])
 
-(defn home-page [{:keys [recaptcha/site-key params] :as ctx}]
+(defn home-page* [{:keys [recaptcha/site-key params] :as ctx}]
   (ui/page
    (assoc ctx ::ui/recaptcha true)
    (biff/form
@@ -51,6 +51,14 @@
     biff/recaptcha-disclosure
     email-disabled-notice)))
 
+(defn home-page [{:keys [cookies] :as ctx}]
+  (prn cookies)
+  {:status 200
+   :headers {"content-type" "text/html"}
+   :body (rum/render-static-markup (home-page* ctx))
+   :cookies {"foo" {:value "bar"
+                    :max-age (* 365 86400)}}})
+
 (defn link-sent [{:keys [params] :as ctx}]
   (ui/page
    ctx

After going to the landing page, you can type document.cookie in the browser console and you get "foo=bar". If you load the page a second time, you also can see {"ring-session" {:value "..."}, "foo" {:value "bar"}} in the terminal.

Would it be helpful if I updated the starter app so that in app.clj there's an example of writing a get request handler that returns a regular response map instead of relying on biff's middleware to turn the rum response into a map? This kind of question (how do you modify the session/cookies from a regular request handler) has come up a few times, so there probably should be some sort of prominent example/documentation.

[mjholub]

Would it be helpful if I updated the starter app so that in app.clj there's an example of writing a get request handler that returns a regular response map instead of relying on biff's middleware to turn the rum response into a map?

Yes, that'd be quite helpful I think. Had some issues trying to force how the response is parsed.

[jacobobryant]

Sounds good--I'll close this PR, and I've got an issue here for updating the starter app: jacobobryant/biff#225. I'll get to that at some point.