Conditionally load laravel api resource-CodePudding

I'm trying to conditionally load a property (not a relationship) in my API Resource class:

'animals' => $this->when(false, AnimalsResource::collection($this->animals), null),

I thought that if the condition was false it wouldn't try to load the property animals. However when I run this I get the following error:

Call to a member function first() on null

How can I remove the property animals from my api response json when it is null?

CodePudding user response：

PHP needs to know all the parameters of a function before calling them.

Doing AnimalsResource::collection($this->animals) will actually generate the result so it can use it to call when.

You can try the following code instead:

'animals' => $this->when(false, function () { 
 return AnimalsResource::collection($this->animals); 
}, null),

in which case the parameter is a function instead of a collection which Laravel might invoke if the first parameter is true

CodePudding user response：

No, it doesn't. The 'when' method only applies to the Api Resource, but you are still invoking the animals property.

You could set something like this

'animals' => $this->when(! is_null($this->animals), AnimalsResource::collection($this->animals), null),

Keep in mind that if you are executing a SQL Statement inside your 'animals' attribute, you could generate a N 1 problem.