Cannot find errors returned by validate method - laravel

Question

I am using the validate method to validate user input and when I post a form with errors, I get redirected to the previous page but the form is not repopulated and the errors are not showing. I have include a partial view for showing errors in the page with the form. The partial view is:
#if ($errors->any())
<div class="alert alert-danger">
<ul>
#foreach ($errors as $error)
<li> {{ $error }} </li>
#endforeach
</ul>
</div>
#endif
the action method in the controller is:
public function store(Request $request)
{
$request->validate([
'product_name' => 'required',
'age' => 'required',
'product_code' => 'required|alpha_num',
'price' => 'required|numeric',
]);
$product=new Product();
The view with the form is:
#section('content')
<div class="container">
#include('partials.errors')
<form action="/products/create" method="POST">
<input type="hidden" name="_token" value="<?php echo csrf_token(); ?>">
#csrf
<div class="form-group">
<label>Product Name</label>
<input name="product_name" type="text" class="form-control">
</div>
<div class="form-group">
<label>Age</label>
<input name="age" type="text" class="form-control">
</div>
<div class="form-group">
<label>Gender</label>
<select class="form-control" name="gender">
<option>
Male
</option>
<option>
Female
</option>
Unisex
</option>
</select>
</div>
<div class="form-group">
<label>Product Code</label>
<input name="product_code" type="text" class="form-control">
</div>
<div class="form-group">
<label>Price</label>
<input name="price" type="text" class="form-control">
</div>
<div class="form-group">
<label>Product Category</label>
<select class="form-control" name="category_name">
#foreach ($product_categories as $product_category)
<option>{{ $product_category->category_name }}</option>
#endforeach
</select>
</div>
<div class="form-group">
<label>Brand</label>
<select class="form-control" name="brand_name">
#foreach ($brands as $brand)
<option>{{ $brand->brand_name }}</option>
#endforeach
</select>
</div>
<button class="btn btn-primary" type="submit">Create</button>
</form>
</div>
#endsection
when I post a failed form, I get redirected to the view with the form but the form is not repopulated with the input that I entered. additionally, the erros are not shown but just an empty red div. According to a book I read, if the data isn’t valid, the validate method throws a ValidationException and the exception will return a redirect to the previous page, together with all of the user input and the validation errors. I am new to laravel.

Answer 1

You should use old() method to keep repopulate entered value in input field like below
<input name="product_code" type="text" class="form-control" value="{{ old('product_code') }}">
To show validation error you have to add errors in each field for example like below
#error("product_code")
<div class="invalid-feedback">{{ $message }}</div>
#enderror
You can read more about old method here
https://laravel.com/docs/8.x/requests#retrieving-old-input
For validation error
https://laravel.com/docs/8.x/validation#the-at-error-directive

Answer 2

First, the CSRF token:
If you check the docs you'll see that you have 2 options how to add it:
#csrf
<!-- Equivalent to... -->
<input type="hidden" name="_token" value="{{ csrf_token() }}" />
You are doing both, remove one of them.
Second, the old input:
You are missing the old input call. For example:
<input name="product_code" type="text" class="form-control" value="{{ old('product_code') }}">
Last, the errors:
You are doing it correctly.
If is still not working, check that your route is using the middleware web.