Laravel In a Nutshell - Form Processing (#8)

In this guide we’ll explore form processing and validation in Laravel while getting some additional practice using Eloquent models to create new data in our database.

To demonstrate this, we’ll create a “Add a new product” page to our store demo.

Routes

To begin, we’ll start with the addition of two new routes in our /routes/web.php file:

# This first new route will show a form to add a new product
Route::get('/products/create', [ProductsController::class, 'create']);

# This second new route will process the form to add a new product
# Note how the method we’re using here is post instead of get since
# we will be processing a form submitted via the HTTP POST method
Route::post('/products', [ProductsController::class, 'store']);

# This is our existing "Show all the products route"
# Make sure the above routes come before this so they take precedence
# Otherwise, a URL like "/products/create" will be interpreted such that "create" is a category
Route::get('/products/{category?}', [ProductsController::class, 'showProductsByCategory']);

To make the /products/create route accessible to the user, we’ll add a new link to our navigation in main.blade.php:

<nav>
    <ul>
        <li><a href='/products'>Products</a></li>    
        <li><a href='/products/create'>Add New Product</a></li>
        <li><a href='/contact'>Contact</a></li>
    </ul>
</nav>

Show form

To respond to the /products/create route, we’ll set up the following method in ProductsController:

/**
* GET /products/create
*/
public function create() 
{
    # To create a new product we’ll need to present a dropdown of categories
    # that product can be associated with. To do this, we’ll need some category
    # data to pass to the view. 
    # The following query will return an array of category names keyed by their id
    $categories = Category::pluck('name', 'id')->all();

    # Return a view to show our form, including the category data
    return view('products-create')->with('categories', $categories);
}

To support the above method, we’ll create a view at /resources/views/products-create.blade.php with this code:

@extends('main')

@section('page-content')
    <h2>Add New Product</h2>

    <form method='POST' action='/products'>
        @csrf
        <label for='product_name'>Product name:</label>
        <input type='text' name='name' id='product_name'>

        <label for='category_id'>Category:</label>
        <select name='category_id' id='category_id'>
            @foreach ($categories as $id => $name)
                <option value='{{ $id }}'>{{ $name }}</option>
            @endforeach
        </select>

        <button type='submit'>Add new product</button>
    </form>
@endsection

Resulting form:

Process form

The above form submits to our /products POST route, which will invoke a store method in our ProductsController that will look like this:

/**
 * POST /products
 */
public function store(Request $request)
{
    # Set up a new instance of our Product model to perist the new product to the database
    # Note how the form data is accessed via the $request object that is passed to this method
    $product = new Product();
    $product->name = $request->name;
    $product->category_id = $request->category_id;
    $product->save();

    # When done, redirect the user back and include a message we 
    # can display on the page as confirmation
    return redirect('/products/create')->with(
        'message',
        'Your product ' . $product->name . ' was added'
    );
}

To output the message that is flashed as part of the redirect we’ll add the following code after our form element in /resources/view/products-create.blade.php:

@if (session('message'))
    {{ session('message') }}
@endif

Result after adding a new product:

Validation

After completing the above steps, we should have a working feature that allows visitors to add new products. To wrap things up, we’ll sprinkle in some basic form validation as shown in the following updated store method code:

/**
 * POST /products
 */
public function store(Request $request)
{
    # ⭐ NEW ⭐
    $request->validate([
        'name' => 'required|unique:products|max:255',
    ]);

    $product = new Product();
    $product->name = $request->name;
    $product->category_id = $request->category_id;
    $product->save();

    return redirect('/products/create')->with(
        'message',
        'Your product ' . $product->name . ' was added'
    );
}

To output any errors caught in validation, add the following code after your form in products-create.blade.php:

@if ($errors->any())
    <ul>
        @foreach ($errors->all() as $error)
            <li>{{ $error }}</li>
        @endforeach
    </ul>
@endif

Result: