Merge pull request #32 from SymfonyCasts/ch3

Add scripts to the 3st chapter

Author: kbond

sfcasts/handle-form.md

@@ -1,3 +1,110 @@
-# Processing the Submitted Form in the Controller
+# Processing the Submitted Form
 
-TODO
+Alright, we've built, created, rendered, and styled our form (I swear, I’ve
+done my best so far!). I've given it my all and now our form is ready for
+submission. Now, as any seasoned backend developer will tell you, the real
+fun begins when we start dealing with that submitted data. Let's jump back
+into our controller and make this form functional. 
+
+## Updating Controller to Handle Form Data
+
+Open up `src/Controller/AdminController.php`, and in the `newStarshipPart()`
+method, right below the form object, add `$form->handleRequest()`. 
+
+To pull this off, we need to pass the current request object to this
+method. You're familiar with this by now. Inject a `$request` from
+HTTP Foundation as a method argument and pass the `$request` to this
+method. You might be wondering what this `handleRequest()` is all about.
+It simply grabs the submitted data from the request, applies that data to
+your form, and now your form contains the user's submitted values. 
+
+## Checking Form Submission
+
+Next, we want to know whether the form has actually been submitted or we just
+load the form page. That's a breeze — just write `if ($form->isSubmitted())`.
+Then within that `if`, we can retrieve the submitted data with `$form->getData()`.
+
+Since our form type has a `data_class` option set to `StarshipPart::class`,
+the data you retrieve here isn't a straightforward PHP array. Instead, it's a
+`StarshipPart` entity instance with the fields already filled in for us.
+Skeptical? Go ahead and check it yourself. Let's assign it to a `$part`
+variable and below `dd($part)`.
+
+## Testing Our Form
+
+Back in the browser, I'll quickly fill in the form. Hit create to submit it
+and voila, a shiny new `StarshipPart` object with the data we sent. Notice
+that no ID is set because Doctrine hasn't saved it in the database yet.
+I'll quickly add a PHPDoc above the variable to make PhpStorm's autocomplete
+happier, and delete the `dd()` statement. 
+
+## Saving Data with Doctrine's EntityManager
+
+To save the new part, we need Doctrine's `EntityManager`. Inject it with
+`EntityManagerInterface $entityManager` in the method signature. Then, back
+in the `if`, add `$entityManager->persist($part)`, passing the `$part`
+object and next `$entityManager->flush()`.
+
+Back to the browser, I'll set the name to: "Legacy Hyperdrive".
+Give it a fair price, and don’t forget about important note:
+
+> Be careful with high revs!
+
+Now, hit the submit button again. Did it finally work? Well, at least there are
+no errors. Head to the `$part` page and search for "legacy hyperdrive".
+There it is, your new shiny Starship part, ready for sale. 
+
+## Celebrating Success with Flash Messages
+
+Let's celebrate this moment properly. I'm going to add a successful flash
+message. Flash messages are temporary messages stored in the session and
+shown exactly once. They are perfect for things like:
+
+> Your part was created successfully!
+
+If you peek into `templates/base.html.twig` You'll see we already have code
+that loops over flash messages and renders them with nice styling depending
+on the type: success, warning, error, default. After saving the entity to the
+database, let's write this: `$this->addFlash()`
+
+First argument: the message “type” - it helps to control styling. Write
+`success` here. Second argument: the content of the message. How about
+`sprintf('The part "%s" was created.', $part->getName())`.
+
+## Avoiding Duplication and Redirecting User
+
+To avoid duplicate form submissions when the user refreshes the page - which
+might lead to unwanted parts floating around in space - let's finish the
+process with a redirect. This is a classic best practice for POST forms.
+Let's return `$this->redirectToRoute()`.
+
+We can redirect anywhere, but I'll send users back to the part list for
+convenience. It should be `app_part_index` route name. 
+
+## Testing the Overall Flow
+
+Alright, let's create a new part again. How about a quantum reactor for the
+name, set a price, and for notes, I'll say:
+
+> Do not exceed 120% core flux
+
+OK, submit the form again, and there it is. Our success flash message,
+announcing that the part quantum reactor was successfully created. And if I
+try to refresh the page, the message is gone, so it was shown only once,
+and Chrome does not ask me if I want to resubmit the form again, so it was
+redirected properly too. Sweet!
+
+## Adding a Second Submit Button
+
+Right now we only have one submit button: Create. But imagine this, if
+you're feeling productive, caffeinated, on a roll, and you want to create
+multiple parts quickly, one after the other, you could do this with a few
+extra clicks each time, clicking on the link to return to the form. But
+wouldn't it be so much faster to have a second submit button, that, instead
+of creating and going back to the list, creates and stays on this page with an
+empty form open, so you can immediately create another part?
+
+Well, it might not be much faster, but it still could save someone a few hours
+of their life over the course of many years of adding those parts.
+You might be wondering, is that even possible? Absolutely! And we'll figure out
+how in the next chapter.