If you want to translate a field in multiple locales with a single form you can use the overridden fill() method which allows you to pass in an array with the locales as first array key and the translated attributes in the sub-array.

'en' => [
'title' => 'My first edited post',
'de' => [
'title' => 'Mein erster bearbeiteter Beitrag',

Request as array syntax

To achieve this structure in your form - to prevent manipulating the form data just to save them. You can use the input name array [] syntax.

<input type="text" name="en[title]" />
<input type="text" name="de[title]" />

Request as plain syntax

If you want, you can structure the request inputs in colon notation too. Notice that with this approach the attribute goes first.

<input type="text" name="title:en" />
<input type="text" name="title:de" />

Saving the request

Both ways are ready to save the translatable attributes to the model without any other modification.

public function update(Request $request, Post $post)

Updating the default locale

You can update the default locale attributes by accessing the translatable attributes from the model itself.

$post->title = 'My first post'; // Will update the English translatable model
$post->fill(['title' => 'My first post']); // Will update the English translatable model