Trouble making foreach loop for multi-dimensional array with StdClass Objects

Question

I'm learning PHP and code igniter, and am new to modern programming in general, so please be kind!

I wrote a function to generate weekly totals of kilometers ridden on a bicycle from a mysql table. My function is generating a multi-dimensional array with Std Class objects. When I try to echo the result in my view file, I get the error : Error: Message: Object of class stdClass could not be converted to string.

I have tried instructions on how to make foreach loops for multi-dimensional arrays in about ten threads, including this one. It appears I need a nested foreach structure, however, I am not understanding how to apply these examples to my code.

//in my controller index function

$weeknumber = array(0, 1, 2, 3, 4, 5, 6, 7);
$bikedata['sums_for_table'] = array_map(array($this->bike_model,
  'get_weekly_sum'), $weeknumber);

//in my model

public function get_weekly_sum($when)
{
    $this->db->select_sum('distance');
    $this->db->where("WEEK (date) = WEEK( current_date ) - $when AND YEAR( date) = YEAR( current_date)");
    $query = $this->db->get('bike_stats');

return $query->result();

//in my view (trimmed for simplicity. It's actually a table.)

foreach ($sums_for_table as $sum_array):
foreach ($sum_array as $key => $object): 
echo $object;  
endforeach;
endforeach;

The function is working correctly in that the array returned by the functions (below, from var_dump) has the info I want in it (the numbers 63.2 etc.) but I'm having trouble understanding how to use the info in this form.

array(8) {
[0]=> array(1) { [0]=> object(stdClass)#23 (1) { ["distance"]=> string(4) "63.2" } }
[1]=> array(1) { [0]=> object(stdClass)#24 (1) { ["distance"]=> string(5) "111.9" } }
[2]=> array(1) { [0]=> object(stdClass)#25 (1) { ["distance"]=> string(4) "48.2" } }
[3]=> array(1) { [0]=> object(stdClass)#26 (1) { ["distance"]=> NULL } }
[4]=> array(1) { [0]=> object(stdClass)#27 (1) { ["distance"]=> string(4) "26.7" } }
[5]=> array(1) { [0]=> object(stdClass)#28 (1) { ["distance"]=> string(4) "42.2" } }
[6]=> array(1) { [0]=> object(stdClass)#29 (1) { ["distance"]=> string(4) "32.3" } }
[7]=> array(1) { [0]=> object(stdClass)#30 (1) { ["distance"]=> string(4) "10.9" } } }

My main question is how I can fix my view file code to properly output the numbers in this array. However, if I could have written my function in a different way to generate a regular associative array I would love to know that too!

Any help would be much appreciated!

gries · Accepted Answer · 2016-07-07 09:34:09Z

1

This should do the trick:

   foreach ($sums_for_table as $entry) {
      $distance = $entry[0]->distance;
      echo $distance . ' <br />';
    }

You can access properties of stdClass Objects by using the $object->property syntax.

I don't know how all of your code works because I don't see it all but for a cleaner way you could try:

// controller
$bikedata['sums_for_table'] = [];
$weeknumbers = array(0, 1, 2, 3, 4, 5, 6, 7);
foreach ($weeknumbers as $weeknumber) {
  $weekResult = $this->bike_model->get_weekly_sum($weeknumber);
  $bikedata['sums_for_table'][$weeknumber] = $weekResult[0]->distance;
}

// view
foreach ($sums_for_tables as $weekNumber => $distance) {
  // draw your table here
}

edited Jul 7, 2016 at 9:34

answered Jul 5, 2016 at 15:14

gries

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2 Comments

Cyclist Over a year ago

Awesome, Gries. Thank you! This works perfectly now. I had tried something along the lines of $object->property but I did not know to specify the key of zero. My table is now displaying perfectly, so now, on to the next step of making this into a bar graph! And thank you also for the cleaner code. I'm going to play with this and see how it works; looks like a good way to make another use of $object->property to help learn it. Those of us who are learning on our own really appreciate thoughtful answers such as yours!

Cyclist Over a year ago

The alternate code initially generated an error message of "trying to get property of nonobject." Then I added the key of zero and it worked great! So the last line of the controller code becomes: $bikedata['sums_for_table'][$weeknumber] = $weekResult[0]->distance;

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