Getting the next object in a collection in Laravel - laravel

Question

I have mutliple Chapters that belong to a Module.
On a chapter page I want to check if I am on the last one in the module, but I'm getting a bit stuck.
// inside Chapter model.
// The $module var is a made by something like Module::with('chapters')->find(1);
public function getNext($module){
// Convert to array so we can call some of
// the array functions to navigate the array
$chapters = $module->chapters->keyBy('id')->toArray();
// get the last element in the array
end($chapters);
// If the last element's key is the same as this one,
// there is no "next" link
if(key($chapters) == $this->id){
return false;
}
// So there must be a next link. First, reset internal array pointer
reset($chapters);
// Advance it to the current item
while (key($chapters) !== $this->id) next($chapters);
// Go one further, returning the next item in the array
next($chapters);
// current() is now the next chapter
return current($chapters);
}
Cool! So this lets me know if there is a next chapter and even returns it as an array with all of its data. But I'm getting into massive problems. The Chapter has a few other methods on it which I can't call on the 'next' element as its an array, not an object any more.
// Chapter.php
public function url(){
return url('chapter/' . $this->id);
}
$module = Module::with('chapters')->find(1);
$chapter = Chapter::find(1);
$next = $chapter->getNext($module);
if( $next )
echo $next->url();
This gives me (obviously)
Call to a member function url() on array
So I need to rewrite this function, but I can't work out how to get the next object in a Laravel collection.
public function getNext($module){
$last = $module->chapters->last();
// If the last element's key is the same as this one,
// there is no "next" link
if($last->id == $this->id){
return false;
}
....
How can I traverse the collection to get the next Chapter as an object?

Answer 1

After a little bit I have worked out my own solution:
public function getNext($module){
$last = $module->chapters->last();
// If the last element's key is the same as this one,
// there is no "next" link
if($last->id == $this->id){
return false;
}
$current_order = $this->order;
$filtered = $module->chapters->filter(function ($item) use ($current_order) {
return $item->order > $current_order;
});
return $filtered->first();
}
Open to any other neater ways of doing it though! Thanks

Answer 2

You can create collection macros as:
Collection::macro('previous', function ($key, $value = null) {
if (func_num_args() == 1) $value = $key; $key = 'id';
return $this->get($this->searchAfterValues($key, $value) - 1);
});
Collection::macro('next', function ($key, $value = null) {
if (func_num_args() == 1) $value = $key; $key = 'id';
return $this->get($this->searchAfterValues($key, $value) + 1);
});
Collection::macro('searchAfterValues', function ($key, $value) {
return $this->values()->search(function ($item, $k) use ($key, $value) {
return data_get($item, $key) == $value;
});
});
Then you can use it as:
$module = Module::with('chapters')->find(1);
$chapter = Chapter::find(1);
$next = $module->chapters->next($chapter->id)
// or
$next = $module->chapters->next('id', $chapter->id)