如何访问嵌套关联数组中的密钥

public function getEntriesArray($sort = 'asc', $studentEntries = false)
{
    if ($studentEntries) {
        $entries = $this->getStudentEntries();    
    } else {
        $entries = $this->getEntries();    
    }

    $arrayOfEntries = array();
    $ojti_totals = array();

    foreach ($entries as $e) {
        $a = array();
        $ojti_totals = array();

        $a['id'] = $e->getId();
        
        $a['start_unix'] = $e->getStart()->format('U');
        $a['start_date'] = $e->getStart()->format('Y-m-d');
        $a['start_time'] = $e->getStart()->format('h:i');

        $a['stop_unix'] = $e->getStop()->format('U');
        $a['stop_date'] = $e->getStop()->format('Y-m-d');
        $a['stop_time'] = $e->getStop()->format('h:i');

        $a['verified'] = $e->getVerifiedAsCorrect();

        $a['position_id'] = $e->getPosition()->getId();
        $a['position_name'] = $e->getPosition()->getName();

        $a['duration'] = $e->getDuration();
        $a['duration_time_human_short'] = $e->getDuration('time_human_short');

        if ($studentEntries) {
            $a['ojti_id'] = $e->getOperator()->getId();
            $a['ojti_signature'] = $e->getOperator()->getSignature();

            //Not the nicest implementation, kind of threw this in afterward. Some duplication going on since this is now stored on every entry, and the last one holds the ackumulated total.
            $ojti_totals[ $a['ojti_id'] ]['signature'] = $a['ojti_signature'];

//problem starts here:

            if ($ojti_totals[ $a['ojti_id'] ]['duration']) {                
                $ojti_totals[ $a['ojti_id'] ]['duration'] = $ojti_totals[ $a['ojti_id'] ]['duration'] + $a['duration']/3600;                    
            } else {
                $ojti_totals[ $a['ojti_id'] ]['duration'] = $a['duration']/3600;                                        
            }

            $a['ojti_totals'] = $ojti_totals;

        } else {
            if ($e->getStudent()) {
                $a['student_id'] = $e->getStudent()->getId();
                $a['student_signature'] = $e->getStudent()->getSignature();
            } else {
                $a['student_id'] = null;
                $a['student_signature'] = '-';            
            }                
        }

        $arrayOfEntries[] = $a;
    }

目的是设定 $ojti_totals[ $a['ojti_id'] ]['duration'] 因此,对于每次迭代,应增加持续时间的现有值。

但我找不到进入的方法 $ojti_总计[$a['ojti_id']['duration'] .

上面的代码导致

注意:未定义索引:持续时间

改成

if (isset($ojti_totals[ $a['ojti_id'] ]['duration']) {

永远不可能是真的。也不是

if (array_key_exists('duration',$ojti_totals[ $a['ojti_id'] ])) {  

5次迭代后阵列的var_转储

array(1) {
  [12]=>
  array(2) {
    ["signature"]=>
    string(2) "CN"
    ["duration"]=>
    float(2.2477777777778)
  }
}
array(1) {
  [12]=>
  array(2) {
    ["signature"]=>
    string(2) "CN"
    ["duration"]=>
    float(0.33333333333333)
  }
}
array(1) {
  [12]=>
  array(2) {
    ["signature"]=>
    string(2) "CN"
    ["duration"]=>
    float(0.75)
  }
}
array(1) {
  [12]=>
  array(2) {
    ["signature"]=>
    string(2) "CN"
    ["duration"]=>
    float(0.96666666666667)
  }
}
array(1) {
  [12]=>
  array(2) {
    ["signature"]=>
    string(2) "CN"
    ["duration"]=>
    float(2.2477777777778)
  }
}