Set simple defaults when declaring PHP-arrays

Question

In JavaScript I can do the following:

var variable = {
  variable: arg || "bla";
}
// variable.variable = "bla" if arg is false, null or unefined
var variable [
   arg || "bla
]
// variable[0] = "bla" if arg is false, null or unefined

If arg isn't defined, the value gets "bla". Pretty neat. I love this!

Is there something similiar possible in php? I can do an if with an isset(), but that produces a lot of code, especially if I have an array like this for example:

$postData = array(
    'birthday' => $aData['oBirthday'] /* ????? */,
    'country' => $aData['sCountry'],
    'first_name' => $aData['sFirstName'],
    'last_name' => $aData['sLastName']
);

EDIT:

The shortest syntax possible I found so far (Thanks to Tom!):

$postData = array(
'birthday' => isset($aData['oBirthday']) ? $aData['oBirthday'] : "aaaaaaaa"
);

@Barmar: Thanks for mentioning. I haven't thought that searching the (pseudo-)syntax would find me anything. — hugo der hungrige
– hugo der hungrige, Commented Jul 5, 2013 at 22:35

Tom van der Woerdt · Accepted Answer · 2013-07-05 22:25:17Z

4

Yeah, PHP has the ?: operator that does the same.

$var = arg ?: "bla";

This is a ternary operator, usually written as condition ? if_true : if_false but :

Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.

answered Jul 5, 2013 at 22:25

Tom van der Woerdt

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7 Comments

hugo der hungrige Over a year ago

I forgot to try that! Thanks! But still this doesn't work in arrays, as I still get an error thrown. Thus +1 and I updated the question.

Tom van der Woerdt Over a year ago

The full version is isset($var['property']) ? $var['property'] : 'default' - maybe try that?

Tadeck Over a year ago

@TomvanderWoerdt: If you have shorthands for retrieving such values, you can do eg. Arr::get($var, 'property') ?: 'default'. Not exactly the same, but may work in this specific case.

Tadeck Over a year ago

@TomvanderWoerdt: Or even better, if shorthands support that, it may simply be like Arr::get($var, 'property', 'default').

hugo der hungrige Over a year ago

@Tom van der Woerdt: I would consider the comment as the answer, as I suppose there is no better way of doing it.

|

Marcovecchio · Accepted Answer · 2013-07-05 22:38:51Z

3

I have faced the same problem years ago, and my solution is a simple function:

function GetArrayData(array $array, $key, $default = NULL)
{
  return isset($array[$key]) ? $array[$key] : $default;
}

Not too elegant, but safe as hell. Use $_GET or $_POST as the array, and you also have a great way to read form or query string data. I use a similar approach to get session values also.

answered Jul 5, 2013 at 22:38

Marcovecchio

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2 Comments

hugo der hungrige Over a year ago

This is a little bit more complicated than necessary, the idea with the setable default is nice however. I'll still would give the credit to Tom, as he was the first to mention ternary operators and thats what beasically every answer is revolving around and the other solutions (including the one offered by myself), are just a matter of what you need.

Marcovecchio Over a year ago

Sure, Hugo! I just think it's all a matter of personal taste. I like using functions / methods instead of inline code, because if I need to change the behavior of this in the future, I have just one place to deal with. It's the DRY principle. And please note the importance of the isset() use here: this is what prevents errors on trying to access non-existent keys on arrays.

Community · Accepted Answer · 2017-05-23 11:56:32Z

1

For single parameters use ternary operators, possibly in the form proposed by Tom in his answer.

For arrays of parameters you can use array_merge():

$defaults = array(
    'birthday' => '1980-03-04',
    'country' => 'United States',
    'first_name' => 'John',
    'last_name' => 'Smith',
);

$params = array(
    'first_name' => 'Jane',
    'last_name' => 'Johnson',
);

$results = array_merge($defaults, $params); // uses $defaults as base

Proof is here: http://ideone.com/0CewM1

edited May 23, 2017 at 11:56

CommunityBot

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answered Jul 5, 2013 at 22:38

Tadeck

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1 Comment

Tadeck Over a year ago

@Jack: Exactly. The only difference is the order (ideone.com/9F0HZC), but it should not matter for most implementations.

Lebugg · Accepted Answer · 2014-02-04 10:01:20Z

0

I know this ugly, but you can do the following:

@ $var = $arr['key'] ?: DEFAULT_VALUE;

I sometimes use it because even though this is bad, I know what it does, so I allow myself to use it.

answered Feb 4, 2014 at 10:01

Lebugg

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