php - 对 PHP 数组进行排序，但对其中的对象进行排序

Question

抱歉，如果这很简单，我是 PHP 新手。

使用基于 REST 的 API，我从正在访问的系统返回以下结果:

$results = Array ( 
    [0] => stdClass Object ( 
        [ID] => 4d74fcda000291fe949dce44b892c57a   
        [name] => File Quarterly Taxes 
        [objCode] => TASK 
        [status] => NEW 
        [plannedCompletionDate] => 2011-09-09T07:30:00:000-0600 
        [description] => 

        [project] => stdClass Object ( 
            [ID] => 4d3d9cb00000829953755920c930f68a
            [name] => 2010 Accounting 
            [objCode] => PROJ
        )
    )
    [1] => stdClass Object ( 
        [ID] => 4d74fcda000291fd43a0b7c9c8224d3a 
        [name] => File Quarterly Taxes 
        [objCode] => TASK 
        [status] => NEW 
        [plannedCompletionDate] => 2011-06-10T07:30:00:000-0600 
        [description] => 

        [project] => stdClass Object (
            [ID] => 4d3d9cb00000829953755920c930f68a 
            [name] => 2010 Accounting 
            [objCode] => PROJ
        )
    ) 
    [2] => stdClass Object ( 
        [ID] => 4d74fcda000291ffd91d63e25945d2be 
        [name] => File Quarterly Taxes 
        [objCode] => TASK 
        [status] => NEW 
        [plannedCompletionDate] => 2012-01-13T07:30:00:000-0700 
        [description] => 

        [project] => stdClass Object ( 
            [ID] => 4d3d9cb00000829953755920c930f68a 
            [name] => 2010 Accounting 
            [objCode] => PROJ
        )
    )
) 

如何获取该数组并按对象中的 plannedCompletionDate 对其进行排序？

Answer 1

function sort_callback( $a, $b ) {
    if( $a->plannedCompletionDate == $b->plannedCompletionDate ) {
        return 0;
    }
    return ( $a->plannedCompletionDate > $b->plannedCompletionDate ) ? 1 : -1;
}

usort( $results, 'sort_callback' );