looping through unknown array keys/testing for missing keys

Question

I am trying to set up a structure where an associative array holds key/value data for a template of mine.

I want to be able to apply default data, but the below code has some obvious problems. First of all, it's a hassle writing that repetitive stuff. Second - the test for null doesn't work if the key isn't defined at all, then you just get an error saying that key 'background_color' is not defined.

How would I best go about structuring something like this?

//Defaults for this template
$default = array();
$default['background_color'] = '#ffffff';
$default['background_image'] = '';
$default['background_opacity'] = '1.0';
$default['background_repeat'] = '';
$default['background_position-horizontal'] = 'left';
$default['background_position-vertical'] = 'top';
$default['background_size'] = '';

if($data['background_color'] == null) { $data['background_color'] = $default['background_color']; }
if($data['background_image'] == null) { $data['background_image'] = $default['background_image']; }
if($data['background_opacity'] == null) { $data['background_opacity'] = $default['background_opacity']; }
if($data['background_repeat'] == null) { $data['background_repeat'] = $default['background_repeat']; }
if($data['background_position-horizontal'] == null) { $data['background_position-horizontal'] = $default['background_position-horizontal']; }
if($data['background_position-vertical'] == null) { $data['background_position-vertical'] = $default['background_position-vertical']; }
if($data['background_size'] == null) { $data['background_size'] = $default['background_size']; }

colburton · Accepted Answer · 2014-06-12 11:12:23Z

1

Use isset instead, and walk through the defaults with a foreach

foreach ($default as $key => $val) {
    if (!isset($data[$key]) {
        $data[$key] = $val;
    }
}

Isset does return false if the value is null, so you don't need an extra check for null.

answered Jun 12, 2014 at 11:12

colburton

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Brandon - Free Palestine · Accepted Answer · 2014-06-12 11:24:04Z

1

//Defaults for this template
$default = array();
$default['background_color'] = '#ffffff';
$default['background_image'] = '';
$default['background_opacity'] = '1.0';
$default['background_repeat'] = '';
$default['background_position-horizontal'] = 'left';
$default['background_position-vertical'] = 'top';
$default['background_size'] = '';

foreach ($default as $k => $v) {
    if (!isset($data[$k])) {
        $data[$k] = $default[$k];
    }
}

edited Jun 12, 2014 at 11:24

Brandon - Free Palestine

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answered Jun 12, 2014 at 11:10

L00_Cyph3r

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4 Comments

L00_Cyph3r Over a year ago

Oops, well better to check it twice than to forget it ;) But I updated it accordingly

Brandon - Free Palestine Over a year ago

I modified your answer to use a ternary as well, it's a bit more concise

FuzzyTree Over a year ago

@BrandonWamboldt disagree about using ternary, it's unnecessary and less efficient than using an if statement. no reason to reassign $data[$k] to $data[$k]

Brandon - Free Palestine Over a year ago

@FuzzyTree Yeah, you're right, I've rolled back the edit

PeteAUK · Accepted Answer · 2014-06-12 11:29:42Z

0

The way I always do a 'default' scenario is:

$data = (array)$data + (array)$default;

edited Jun 12, 2014 at 11:29

answered Jun 12, 2014 at 11:16

PeteAUK

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2 Comments

Matt Welander Over a year ago

From what I have tested so far, this answer best suits my needs. I propably didn't specify clearly in the initial question that I need all my default values present, even if the $data array doesn't have them.

PeteAUK Over a year ago

Glad that you found it useful. I picked up this method doing things in Javascript and found it to be the cleanest way of doing this type operation. Biggest thing to remember is that the earliest arrays always takes priority over the later :)

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