How to provide a default model object for relationships?

Laravel: How to provide a default model object for relationships?

If you have a relationship (such as a belongsTo()) relationship, it might not always return a result.

This will then mean that every time you do something like this:

  1. $post = Post::first();
  2. $author = $post->author; // what if the relationship in author() returns nothing?
  3. echo $author->name; // $author might have been null, so this will cause an error

There are three main options to handling this:

1) wrap everything in optional() (which will let you do anything to that variable and it will return null if there was nothing set).

2) Wrap everything in if ($author) { ... } to make sure $author isn't a null value

3) or set a default model. If nothing is found for a relationship then it will create an empty object (of the same type as the relationship defines - in the case below it will be \App\User).

  1. /**
  2.  * Get the author of the post.
  3.  */
  4. public function user()
  5. {
  6.     return $this->belongsTo('App\User')->withDefault();
  7. }
  8.  
  9. // you can also define some defaults for the default!
  10.  
  11. /**
  12.  * Get the author of the post.
  13.  */
  14. public function user()
  15. {
  16.     return $this->belongsTo('App\User')->withDefault([
  17.         'name' => 'Guest Author',
  18.     ]);
  19. }
  20.  
  21. /**
  22.  * Get the author of the post.
  23.  */
  24. public function user()
  25. {
  26.     return $this->belongsTo('App\User')->withDefault(function ($user) {
  27.         $user->name = 'Guest Author';
  28.     });
  29. }

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webdevetc

I am a 29 year old backend web developer from London, mostly focusing on PHP and Laravel lately. This (webdevetc.com) is my blog where I write about some web development topics (PHP, Laravel, Javascript, and some server stuff). contact me here.



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