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A Route for POST Requests
8:47We've set our new wiki page form up to submit via an HTTP POST request. But we're getting the error "Sinatra doesn't know this ditty". The problem is that we need to set up a Sinatra route to handle POST requests.
We've set our new wiki page form up to
submit via an HTTP POST request, but
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we're getting the error Sinatra
doesn't know this ditty.
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The problem is that we need to set up
a Sinatra route to handle POST requests.
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Down here Sinatra provides us with
a sample route to get us started,
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post to the /create path.
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Let's go back in our main app code and
add a post route there.
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Just as you used Sinatra's GET method to
set up routes to handle HTTP GET requests,
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you use Sinatra's POST method to set
up routes for HTTP POST requests.
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The post method works in much
the same way as the get method.
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You call the method and
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pass of a string with the request path
should match /create in this case.
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Then you pass it a block that should
be called whenever a matching post
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request is received.
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For now we'll just have the block
respond to the browser with a string.
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Hello from the post "/create" route!
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By the way, you may be
remembering how our get new route
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conflicted with the URL parameter
in the get title route.
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You may be wondering if it's
okay to define our post
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create route down here at
the bottom of the file.
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There's no need to worry.
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None of the get routes will match our
post request no matter what the path
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is because the request type is different.
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We might need to be concerned if
there were another post route with
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a URL parameter.
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But since this is the only post route,
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we can define it anywhere
in the file we want.
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Let's test this new route.
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Remember because we made
a change to our Ruby code,
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we have to restart the server
even if it's already running.
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Now, I'll visit form to create a new page,
fill it out.
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And then submit it, which should send
a POST request to the /create path.
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And in response,
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instead of an error, we see our string,
Hello from the post "/create" route!
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Our route is being mapped successfully.
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Displaying placeholder messages
is all fine and good, but
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we need a route to take our form data and
save a new Wiki page for us.
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Remember our route to view
an individual page which
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got the page title from a URL parameter?
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That parameter was made available within
the route block through the params hash.
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Form parameters from POST requests
also get placed into the params hash.
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We can look at the form
parameters by calling the inspect
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method on params which
converts the hash to a string.
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So I'll replace our placeholder text, and
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get the parames hash and
call the inspect method on it.
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Now if we restart the server,
and fill out the form.
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And submit it, we'll see the title
we entered under the title key.
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And the content we entered
under the content key.
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Let's copy this string, and
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paste it temporarily in a comment right
above our route so we can refer to it.
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So remember the save content
method we set up previously?
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It takes the title string and
the content string.
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And saves the content to a text file for
us.
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And now we finally have the title and
the content ready to pass to it is input.
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We'll call save_content
within our route block.
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For the title, we'll pass it the value
from the title key of the params hash.
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And for the content,
we'll pass it the value from
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the content key, params["content"].
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Let's restart our server again.
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We'll visit the new page form.
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It's already filled out from our prior
submission, and let's submit it again.
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We'll see only a blank page in response.
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But if we go back to our workspace,
refresh our file list,
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And look in the pages directory,
we'll see a text file with the page
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title we entered as its name and
the contents we entered as its content.
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If we go back to the preview again, fill
out the form again, And submit it again,
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we'll get another blank page but, we can
go back to the workspace, refresh again.
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And we'll see another new file
based on our form contents.
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We're successfully saving our form data.
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There is one more detail to take care of.
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We don't want the browser to just show
a blank page after we submit the form.
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So the final thing we'll do is
tell the browser to make a GET
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request to show the new
page after it's saved.
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To do that will add a call to the redirect
method at the end of a route block.
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The redirect method tells Sinatra to
send a redirect response to the browser,
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redirects cause the browser to send the
GET requests for a particular URL or path.
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Whatever string you pass to
the redirect method, that's the URL or
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path the browser will be redirected to.
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The path for the new page will consist
of a slash followed by the page title.
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So we'll use the title parameter to
construct the path for the redirect.
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So we'll start the string with a slash and
then interpolate the title parameter,
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Into the string.
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Our route should be complete now, so
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we shouldn't need
the reference comment anymore.
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Let's delete that.
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Let's restart the server again.
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Now we can go back to the new page form.
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Submit a new page.
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And once the page is saved
we'll be redirected to view it.
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This works fine until we try to submit
a new page that has a space in the title.
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At that point the page
will seem to lock up and
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may eventually return
a 502 bad gateway message.
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We've seen that when Sinatra starts
up it prints a bunch of debug
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messages to the terminal.
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If Sinatra encounters any
errors while it's running,
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the error messages get
logged in the terminal too.
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Let's go back to our workspace and look at
the Sinatra log messages in the console.
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We'll scroll up until we find the problem.
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InvalidURIError.
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URI basically means the same thing as URL.
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We'll also see the URL that the create
route tried to redirect us to.
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The problem is that spaces aren't
a valid character within a URL,
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they need to be encoded.
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If you type a space into
your browser address bar or
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click on a link with a space,
it'll be okay.
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Let's try this here, Alena Holligan,
note the space in there.
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Your browser encodes the space
characters when it sends the request.
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But when we're sending
a redirect back to the browser,
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we need to encode the URL ourselves.
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We can do that with the URI module.
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It's part of the Ruby standard library,
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which means it's included
with every Ruby distribution.
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The URI escape method can escape that is,
encode the redirect path for us.
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First we're going to need to load
the URI library at the top of the file,
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right here and to require "sinatra"
we'll type, require 'uri".
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Note that it's named uri,
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not URL, if you type URL here,
the library will fail to load.
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Then we'll take our redirect path and
pass it exactly as it is URI.escape.
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The return value of URI.escape
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will be the same path string except
that if it contains any bases or
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other invalid characters,
they'll be encoded so the path is valid.
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Now let's restart our server.
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And now I'll try submitting a page
with a space in the title again.
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We've already got the form filled out,
let's click Submit.
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And this time we're successfully
redirected to the new page.
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And there are no errors from
Sinatra logged in the console.
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Our users can create new pages now,
nice work.
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We set up one Sinatra route that
lets users send GET requests for
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a new HTML form.
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Then we set up a second route that accepts
POST requests with the form data and
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saves it to a file.
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We've shown you techniques to
load existing page data and
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to save new page data.
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In the next stage,
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we'll combine those abilities to
let users edit existing pages.
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