Response using Transformer

You'll need to install laravel-datatables-fractal package if you haven't already.

When using tranformer, all response manipulations must be done via transformer. Thus addColumn, editColumn, removeColumn, setRowAttr, setClassAttr, etc... should be avoided when using fractal.

Closure

You can pass a closure which will receive an item of the result collection and should return an array.

use DataTables;
use App\User;

Route::get('user-data', function() {
    $model = User::query();

    return DataTables::eloquent($model)
                ->setTransformer(function($item){
                    return [
                        'id'         => (int) $user->id,
                        'name'       => $user->name,
                        'email'      => $user->email,
                        'created_at' => (string) $user->created_at,
                        'updated_at' => (string) $user->updated_at,
                    ];
                })
                ->toJson();
});

Thus you can make use of Laravel API Resource.

use DataTables;
use App\User;
use App\Http\Resources\UserResource;

Route::get('user-data', function() {
    $model = User::query();

    return DataTables::eloquent($model)
                ->setTransformer(function($item){
                    return UserResource::make($item)->resolve();
                })
                ->toJson();
});

Transformer

You can use Transformer class.

use DataTables;
use App\Transformers\UserTransformer;

Route::get('user-data', function() {
    $model = App\User::query();

    return DataTables::eloquent($model)
                ->setTransformer(new UserTransformer)
                ->toJson();
});

Manual Way

Create a transformer class, preferably named as below.

app\Transformers\UserTransformer.php

namespace App\Transformers;

use App\User;
use League\Fractal\TransformerAbstract;

class UserTransformer extends TransformerAbstract
{
    protected $availableIncludes = ['posts'];

    /**
     * @param \App\User $user
     * @return array
     */
    public function transform(User $user)
    {
        return [
            'id'         => (int) $user->id,
            'name'       => $user->name,
            'email'      => $user->email,
            'created_at' => (string) $user->created_at,
            'updated_at' => (string) $user->updated_at,
        ];
    }

    /**
     * @param \App\User $user
     * @return \League\Fractal\Resource\Collection
     */
    public function includePosts(User $user)
    {
        $posts =  $user->posts;

        return $this->collection($posts, new PostTransformer);
    }
}

Artisan Command Way

You can use make:transformer command to generate boilerplate.

php artisan make:transformer User

namespace App\Transformers;

use League\Fractal\TransformerAbstract;
use App\User;

class UserTransformer extends TransformerAbstract
{
    /**
     * @param \App\User $user
     * @return array
     */
    public function transform(User $user)
    {
        return [
            'id' => (int) $user->id,
        ];
    }
}

Or even with included class.

php artisan make:transformer User Post

namespace App\Transformers;

use League\Fractal\TransformerAbstract;
use App\User;
use App\Post;

class UserTransformer extends TransformerAbstract
{
    protected $availableIncludes = ['post'];

    /**
     * @param \App\User $user
     * @return array
     */
    public function transform(User $user)
    {
        return [
            'id' => (int) $user->id,
        ];
    }

    /**
     * @param \App\User $user
     * @return \League\Fractal\Resource\Collection
     */
    public function includePost(User $user)
    {
        return $this->collection($user->post, new PostTransformer);
    }
}

Then you can make final changes.

namespace App\Transformers;

use League\Fractal\TransformerAbstract;
use App\User;
use App\Post;

class UserTransformer extends TransformerAbstract
{
    protected $availableIncludes = ['posts'];

    /**
     * @param \App\User $user
     * @return array
     */
    public function transform(User $user)
    {
        return [
            'id'         => (int) $user->id,
            'name'       => $user->name,
            'email'      => $user->email,
            'created_at' => (string) $user->created_at,
            'updated_at' => (string) $user->updated_at,
        ];
    }

    /**
     * @param \App\User $user
     * @return \League\Fractal\Resource\Collection
     */
    public function includePost(User $user)
    {
        return $this->collection($user->posts, new PostTransformer);
    }
}