This is something really simple, the perfect assignment for a Monday morning.
Go to your site's root directory (usually /var/www) and edit the .htaccess file (type sudo nano .htaccess)
Add the following line to the end of the file:
ErrorDocument 404 /rockets-404.lsp
Now any 404 (page not found) errors will redirect to this page instead of displaying the generic Apache error.
This would be a PERFECT message to test out adding comments to.. if you know what I mean. Hint, hint.Comments (13)
Yes, with Rocket Captcha(tm) and everything!
You can't do anything once you sign in (like post messages or anything) yet but... you'll have an account!
Sometimes you want your application to remember where you were, but the application wants to redirect you to somewhere else.
This is most annoying when you sign in. You probably want to stay on the page you were on instead of being redirected back to the main page.
Rockets adds a global variable called (active-page). You have to set it before you call the navigation bar so it knows which page to highlight. But it also passes this variable as a hidden field in the navigation bar itself, alongside the user email and password, so that the verification script (rockets-verify.lsp) can redirect you back to that page if you either succeeded or failed in signing in.
Paging code is really easy in SQLite. You do a SELECT statement as normally but add the LIMIT clause with two numbers separated by a comma. The first number is the offset, aka where you start from, and the second number is the number of results you want back. So if you wanted ten results starting from the thirtieth, you just SELECT ... LIMIT 30,10 and that's it!
Displaying the current paging links is something I might want to do a lot, so I made a function in Rockets to do it. The function works like this:
(display-paging-links int-start-page int-total-pages int-current-page str-page-url)
So to display the top ten pages you'd call (display-paging-links 1 10 1 "rockets-main").
Neat and easy!
Eliminating duplicate code is a great thing. If you have code that is duplicated on many pages, if you want to change it you have to remember to change it on all your pages.
I originally made a framework function (display-navbar) that displays a navigation bar and sign-in form. This was great, but (display-navbar) needs to take a list as an argument to decide what menus to actually show. I didn't want to repeat this list on each page, but I also needed a way to show which page was currently active.
One way would be just to define a new function, (display-rockets-nav "active page") that would then call (display-nav) and specify which page is actually active. But then I would want to make sure this function is defined on every page. Well, I already have a set of common functions in the partial "rockets-common-functions.lsp". I could just put it in there.
The other option is to define a new partial page, "rockets-navbar.lsp", and call this partial each time. Which approach is better? They both require the same amount of code (I have to add a line to either call the function or display the partial). The only real difference is that if I go the function route I would have to have two functions, one in the framework, and one in the application, that had similar names, and I'd have a function calling a function. If I put it in a partial file, it looks like it is doing something different.
Ultimately it's an aesthetic choice. If you make your own application you might decide to do it differently. I might even change my mind at some point!
An existential question, indeed...
For no apparent reason I decided to write a whole essay about it: http://newlisponrockets.com/rockets-why.lsp
Cookie security is something many sites don't bother with, because who would ever fake a cookie? Well, as it turns out, a lot of people could do just that.
Cookie security best practices have been known for a while. This article from 2005 lays them out pretty nicely: http://fishbowl.pastiche.org/2004/01/19/persistent_login_cookie_best_practice/
Basically, you want to have a random number as your cookie, but then the value should not just be the user Id. It should be hard to guess. And what if a user registers and then copies your carefully-selected random number cookie but just changes the user id? Then they could log in as any user they wanted!
So what we do is add some salt to the cookie in the form of ANOTHER random number, each one unique to each user. The salt is stored in the user database, so it isn't available to the public. This makes every cookie unique for each user.
You also want to be running everything under SSL (aka https) to avoid issues with people stealing cookies with things like FireSheep over WiFi connections, but that's something that can be up to the site administrator.
It's no Cave Troll, but it will have to do.
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I have implemented redirections, which are basically just HTTP status codes that point the site to a new page. The command is:
The way it works is that if the logic in your code (say, successfully signing in) should then move you to another page, it does so and immediately exits, without printing anything else, even if you have put (display-page) later on in the page. So, in our example, if the username and password are valid, it just puts you back to the main page. If they are not valid, it will display a message normally with (display-page).