How to get back the value of a variable/dynamic variable?

Development
1

I’m building my first snippet but I’m blocked with a PHP problem.

I have several classical variables (2 for each weekday) :

    $place_monday_midday = "11";
    $place_monday_evening   = "11";
    $place_tuesday_midday   = "12";
    $place_tuesday_evening   = "15";
    $place_wednesday_midday   = "19";
    $place_wednesday_evening   = "11";
    ...

But I also have several “if” to check the current week day ($current_day) and if we are the midday or the evening ($when)

After all this tests on dates and times, I get this :

$where = '$place_'.$current_day."_".$when;

If I do echo $where; I get $place_monday_evening which is correct.

My question is : how to get the value (11 in this example) as return for my snippet ?

2

With snippets, you can just output with PRINT, or better yet you can call a chunk and output into the chunk variables. I assume you will want to output all those variables, that can be done manually or programmatically

3

Give this a try. I think by having the ' at the start of $place you’re initialising a string rather.

$where = $place_'.$current_day.'_'.$when;

return $where;
4

@lkfranklin That’s invalid syntax.

When you have the name of a variable in a variable (in your example, $where = '$place_monday_evening';), you can use $$variable to get its value, like $$where.

Off-hand I’m not entirely sure if that expects the value of $where to start with $or not, so you can try with or without the $ in $place to see which one works.

That said, this is an awfully old, and difficult to understand mechanic, which I honestly wouldn’t recommend using.

Instead, consider a different pattern, like an array lookup:

$map = [
  'monday' => [
     'midday' => 11,
     'evening' => 11,
  ],
  'tuesday' => [
     'midday' => 12,
     'evening' => 15,
  ]
];

return $map[$current_day][$when];

Still not the best code (try checking if keys/values exist before accessing them) but less magical and much easier to understand.

In MODX snippets, the output must always be in a return. Other methods, like print/echo/var_dump are useful for simple debugging, but bypass the MODX parser and can lead to unexpected results.

The best PHP resource, besides the official docs, is probably PHP: The Right Way which goes into way more than you’ll need, but may be a good reference to keep in mind.

3 Likes
5

OK I got it !
Thanks for the array lookup :slight_smile:

1 Like