由于sortBy的Laravel分页错误

Question

I am trying to paginate an eloquent object but i can't get it to work. The paginate throws a error because $products is not a query builder object but a collection.

// i get this value from a $POST variable
$customOrderIds = [3,2,1,4,6,5,9,8,10,7,11,12,13,14,15,16,17,20,18,19,21,22]; // I want the products ordered in this sequence
$products = Product::get()->sortBy(function($product) use($customOrderIds) 
{
    return array_search($product->id, $customOrderIds);
});

$products->paginate(5); // Error is thrown here

I want to keep the order of products that is defined in the $customOrderIds

In other questions they suggest to replace get() function with the paginate function but then my custom order will be only applied to the 5 items in the pagination.

I would rather not use anything with raw sql

Answer 1

paginate is an Eloquent method, so it won't work on your collection. However, collections have a forPage method, which you can use:

The forPage method returns a new collection containing the items that would be present on a given page number. The method accepts the page number as its first argument and the number of items to show per page as its second argument

So what you'll need is

$products->forPage(1, 5);

Answer 2

You have to indeed replace the get with the paginate , but you'll have to do the sorting before you paginate . You can try something along the lines of:

Product::orderByRaw(
    'FIELD(id,3,2,1,4,6,5,9,8,10,7,11,12,13,14,15,16,17,20,18,19,21,22)'
)->paginate(5);

Sources:

https://laravel.com/docs/5.8/queries#raw-expressions https://laracasts.com/discuss/channels/eloquent/custom-orderby-in-laravel-query-builder