Iterating array/hashmap

Question

Edit: Nico Parodi's answer is correct. I will eventually return to finding out why, but for now I will just take it as it is and hope nothing else fails.

I have a table with three fields: "date", "name", "location". I want to group all the records selected from this table based on their date.

By copy-pasting some code from php mysql group by date with yyyy-mm-dd format, I've managed to get this array, date -> name:

$result = mysqli_query($con,"SELECT date, name, location FROM events");
while($row = mysqli_fetch_array($result)) {
    $foo[$row['date']][]=$row['name'];
}

Everything's great, I can iterate it without issues. Now I want to store all the row columns as a value for the date key, so I try to store the entire row as a value:

$result = mysqli_query($con,"SELECT date, name, location FROM events");
while($row = mysqli_fetch_array($result)) {
    $foo[$row['date']][]=$row;
}

And now I can't iterate it. count($rowCol) seems to give me the nr of columns in all the array for either keys, not just for one. How can I iterate it?

foreach($foo as $date => $events) {
    echo $date . ": "; // this is okay         

    foreach($events as $key => $rowCol){
        for ($i = 0; $i<count($rowCol); $i++) {
            echo $rowCol[$i] . " ";     
        }
    }
}

Please edit, I can't see it - this is a simplified version of my code. The actual one compiles/runs fine. — Buffalo
– Buffalo, Commented Jun 18, 2013 at 18:59
use var_dump($events); under echo $date . ":"; and post the output — Mehdi Karamosly
– Mehdi Karamosly, Commented Jun 18, 2013 at 19:08

Nico · Accepted Answer · 2013-06-18 19:18:57Z

1

for ($i = 0; $i<count($rowCol); $i++) {
    echo $rowCol[$i] . " ";     
}

$rowCol has the double of fields that you expect as mysqli_fetch_array() fetches as both associative and numeric array. So,

for ($i = 0; $i<(count($rowCol)/2); $i++) {
        echo $rowCol[$i] . " ";     
    }

should work.

answered Jun 18, 2013 at 19:18

Nico

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4 Comments

Nico Over a year ago

Because mysqli_fetch_row() fetches only as numeric array so you now have the number of fields you always expected, so in this case you don't have to use count($rowCol)/2, just use as before, count($rowCol).

Nico Over a year ago

use var_dump($rowCol) to print the array and see why it has the double of fields

Buffalo Over a year ago

Minor question: can I also get the key when I'm iterating? the name of the table column?

Karim Over a year ago

yes, to do it you should change mysqli_fetch_array call to mysqli_fetch_assoc to fetch results into only associative array - and then you can use foreach ($rowCol as $colName=>$val)

Mehdi Karamosly · Accepted Answer · 2013-06-18 19:20:15Z

1

Replace :

    for ($i = 0; $i<count($rowCol); $i++) {
        echo $rowCol[$i] . " ";     
    }

By

    foreach($rowCol as $k =>$v) {
        echo $v . " ";     
    }

answered Jun 18, 2013 at 19:20

Mehdi Karamosly

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Comments

Karim · Accepted Answer · 2013-06-18 19:22:52Z

1

for ($i = 0; $i<count($rowCol); $i++) {
        echo $rowCol[$i] . " ";     
    }

this part of code doesn't work because rowCol is an associative array + numeric array. Try to replace mysqli_fetch_array with mysqli_fetch_row

edited Jun 18, 2013 at 19:22

answered Jun 18, 2013 at 19:10

Karim

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2 Comments

Buffalo Over a year ago

Mind posting the appropriate foreach? believe me, I've tried to no avail.

Karim Over a year ago

update: my fault, try to replace mysqli_fetch_array with mysqli_fetch_row

Ast Derek · Accepted Answer · 2013-06-18 19:27:09Z

1

Can you tell us what's the output of this code? (show plain text, no HTML):

foreach($foo as $date => $event) {
    echo $date . ": ";

    foreach($event as $key => $value){
        print_r($value);
    }

    echo "\n";
}

Original answer:

$events contains a single event, your code should look more like this:

foreach($foo as $date => $event) {
    echo $date . ": ";

    foreach($event as $key => $value){
        echo $value . " ";
    }

    echo "\n";
}

edited Jun 18, 2013 at 19:27

answered Jun 18, 2013 at 19:09

Ast Derek

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1 Comment

Buffalo Over a year ago

This prints out "2001-02: Array 2012-02: Array 2012-03: Array 2013-03: Array Array".

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