php - What is the syntax for sorting an Eloquent collection by multiple columns?

Question

I know that when using the query builder, it is possible to sort by multiple columns using

...orderBy('column1')->orderBy('column2')

but now I am dealing with a collection object. Collections have the sortBy method, but I have not been able to figure out how to make it work for multiple columns. Intuitively, I initially tried to use the same syntax as orderBy.

sortBy('column1')->sortBy('column2)

but this apparently just applies the sorts sequentially and it ends up sorted by column2, disregarding column1. I tried

sortBy('column1', 'column2')

but that throws the error "asort() expects parameter 2 to be long, string given". Using

sortBy('column1, column2')

doesn't throw an error, but the sort appears to be pretty random, so I don't really know what that actually does. I looked at the code for the sortBy method, but unfortunately I am having a hard time understanding how it works.

Answer 1

sortBy() takes a closure, allowing you to provide a single value that should be used for sorting comparisons, but you can make it a composite by concatenating several properties together

$posts = $posts->sortBy(function($post) {
    return sprintf('%-12s%s', $post->column1, $post->column2);
});

If you need the sortBy against multiple columns, you probably need to space pad them to ensure that "ABC" and "DEF" comes after "AB" and "DEF", hence the sprint right padded for each column up to the column's length (at least for all but the last column)

Note that it's generally a lot more efficient if you can use an orderBy in your query so the collection is ready-sorted on retrieval from the database