如何将PHP数据的多维数组转换为HTML表？

Question

I'm trying to display a formatted HTML timetable using PHP.

I would like to output data from a multi-dimensional array to an HTML table that's formatted with a total of 8 columns (a column for each day Mon-Sun plus a column on the left showing the start times for each session). The amount of rows depends on how many sessions there are for each day.

My solution works to a degree and you can see the output in the following image but you can also see that an extra row is generated for some reason. It's always just one extra row no matter the amount of sessions in a day.

The data is represented like this:

Array
(
[0] => Array
    (
        [0] => Array
            (
                [id] => 1
                [name] => A Monday Session
                [start_time] => 10:00
            )

        [1] => Array
            (
                [id] => 5
                [name] => Another Monday Session
                [start_time] => 11:00
            )

        [2] => Array
            (
                [id] => 6
                [name] => Yet Another Monday Session
                [start_time] => 12:00
            )

    )

[1] => Array
    (
        [0] => Array
            (
            )

    )

[2] => Array
    (
        [0] => Array
            (
                [id] => 8
                [name] => A Wednesday Session
                [start_time] => 14:30
            )

    )

[3] => Array
    (
        [0] => Array
            (
                [id] => 3
                [name] => A Thursday Session
                [start_time] => 09:00
            )

    )

[4] => Array
    (
        [0] => Array
            (
            )

    )

[5] => Array
    (
        [0] => Array
            (
            )

    )

[6] => Array
    (
        [0] => Array
            (
                [id] => 4
                [name] => A Sunday Session
                [start_time] => 13:00
            )

    )

)

As you can see the main keys represent the days of the week. 0 = Monday, 1 = Tuesday etc. Each day then has a list of sessions. In this example Monday has 3 sessions, and Wed,Thu,Sun each also have one.

Notice that they all have different starting times. The moment a session is introduced to the data with a duplicate start time, then extra rows are also created instead of sharing the same row. See output with the Thursday session changed to 10:00 to be the same as Monday:

And here is my buggy solution. I've marked with a comment the line where I'm going wrong.

    // $sessionRows is the array of arrays containing the data above.

    // Grabs array of session times from $sessionRows that has been sorted and duplicates removed.
    // Current values: Array ( [0] => 09:00 [1] => 10:00 [2] => 11:00 [3] => 12:00 [4] => 13:00 [5] => 14:30 )
    $sessionTimes = $this->getSessionTimes($days);

    $numOfRows = count($sessionTimes);
    $numOfCols = $dayIdx;

    // Create grid with correct dimensions and rows represented by the session times
    $grid = array();
    for($i=0;$i<count($sessionTimes);$i++) {
        $row = array();
        for($j=0;$j<$numOfCols;$j++) {
            $row[] = '<td></td>';
        }
        $grid[$sessionTimes[$i]] = $row;
    }


    // Populate grid with session info added to correct coordinates.
    for($i=0;$i<$numOfCols;$i++) {
        echo count($sessionRows[$i]);
        for($j=0;$j<count($sessionRows);$j++) {
            $grid[$sessionRows[$i][$j]['start_time']][$i] = $sessionRows[$i][$j];
        }
    }

    $rows='';
    $idx = 0;
    foreach($grid as $rowArray) {
        $rows .= '<tr>';
        /*** This lines is the problem! It adds the session time as the first column. ***/
        $rows .= '<td class="time-col">'.$sessionTimes[$idx].'</td>';
        for($i=0;$i<count($rowArray);$i++) {
            if(!empty($rowArray[$i]['name'])){
                $rows .= '<td>'.$rowArray[$i]['name'].'<br>'.$rowArray[$i]['start_time'].'</td>';
            } else {
                $rows .= '<td> - </td>';
            }
        }
        $rows .= '</tr>';
        $idx++;
    }

return $rows;

Answer 1

The problem was the $sessionTimes array was having duplicates removed by using the array_unique() function.

This function was preserving the index of the removed values. So the extra rows were being created without value.

Changing this to array_values(array_unique($array)) allowed regenerated keys and fixed the issue.

Thanks to anyone who had a look at it, wish I'd realised this earlier!

Answer 2

Here is an alternative solution that uses less loops.

What it does is it loops through the times, then loops through each day to determine whether the session start_time matches, if it does, add it to the output table.

<?php

$sessionTimes = ['09:00', '10:00', '11:00', '12:00', '13:00', '14:30'];

$schedule = [
    [
        [
            'id' => 1,
            'name' => 'A Monday Session',
            'start_time' => '10:00'

        ],
        [
            'id' => 5,
            'name' => 'Another Monday Session',
            'start_time' => '11:00'

        ],
        [
            'id' => 6,
            'name' => 'Yet Another Monday Session',
            'start_time' => '12:00'

        ],
    ],
    [
       []    
    ],
    [
        [
           'id' => 8,
           'name' => 'A Wednesday Session',
           'start_time' => '14:30'
        ]    
    ],
    [
        [
            'id' => 3,
            'name' => 'A Thursday Session',
            'start_time' => '09:00'
        ]    
    ],
    [
        []
    ],
    [
        []
    ],
    [
        [
            'id' => 4,
            'name' => 'A Sunday Session',
            'start_time' => '13:00'
        ]
    ]
];

$output = '<table><thead><tr><th></th><th>Monday</th><th>Tuesday</th><th>Wednesday</th><th>Thursday</th><th>Friday</th><th>Saturday</th><th>Sunday</th></thead><tbody>';

foreach ($sessionTimes as $sessionTime) {
    $output .= '<tr><td>'.$sessionTime.'</td>';

    $day = 0;
    for ($i = 0; $i < count($schedule); $i++) {
        if ($i == $day) {
            $sessionAtTime = '<td>-</td>';
            foreach ($schedule[$day] as $session) {
                if (!empty($session) && $session['start_time'] == $sessionTime) {
                    $sessionAtTime = '<td><b>' . $session['name'] . '</b><br>Start: ' . $sessionTime.'</td>'; 
                }
            }
            $output .= $sessionAtTime;
            $day++;
        }
    }

    $output .= '</tr>';
}

$output .= '</tbody></table>';

echo $output;