PHP associative array equivilent to Python dict.get()

Question

I've been out of the PHP world for a couple years and I've recently inherited a PHP project. Something that should be fairly easy in PHP is eluding me though. In Python I can do the following:

value = some_dict.get(unknown_key, default_value)

My first guess to do the same in PHP was:

$value = $some_array[$unknown_key] || $default_value;

But $value becomes a boolean because PHP doesn't support value short-circuiting. I also get a Notice: Undefined index: the_key but I know I can suppress that by prefixing @.

Is there I way to accomplish similar behavior in PHP to Python's dict.get(key, default)? I checked PHP's list of array functions but nothing stood out to me.

@adamr I like your solution the best. Post it as an answer and I'll accept it. — ohmu
– ohmu, Commented Mar 20, 2014 at 16:40
Note that even in Python, some_dict.get(unknown_key, default_value) is not the same as some_dict.get(unknown_key) or default_value. The first will only return default_value if the key unknown_key is not within the dictionary, whereas the latter will return default_value if the key is not found or if the value is falsey. — Flimm
– Flimm, Commented Feb 9, 2017 at 15:53

Luke · Accepted Answer · 2014-03-20 16:32:06Z

7

I guess you want something along the lines of the following:

$value = array_key_exists($unknown_key, $some_array) ? $some_array[$unknown_key] : $default_value;

This checks that the key exists and returns the value, else will assign the default value that you have assigned to $default_value.

edited Mar 20, 2014 at 16:32

answered Mar 20, 2014 at 16:08

Luke

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steven · Accepted Answer · 2014-03-20 16:10:12Z

4

$value = isset($some_array[$unknown_key]) ? $some_array[$unknown_key] : $default_value;

This way you won't need to suppress warnings

answered Mar 20, 2014 at 16:10

steven

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Flimm Over a year ago

Note that this is not exactly the same as Python's some_dict.get(unknown_key, default_value) for the case where the key is set but the value is null (or None in Python's case). This is the difference between isset and array_key_exists stackoverflow.com/q/3210935/247696

dogmatic69 · Accepted Answer · 2021-11-14 13:59:58Z

1

Try this:

$value = $some_array[$unknown_key] ?: $default_value;

This is equivalent to this line of code in Python:

value = some_dict.get(unknown_key, default_value)

Note that in the edge-case that the key exists but its value is falsey, you will get the $default_value, which may not be what you intend.

edited Nov 14, 2021 at 13:59

dogmatic69

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answered Mar 20, 2014 at 20:54

adamr

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3 Comments

Luke Over a year ago

Note that this short hand ternary operator is only available from PHP v5.3 and above.

phihag Over a year ago

This will also generate an E_NOTICE-level warning.

Flimm Over a year ago

Sorry for the multiple edits, but I think this much clearer now.

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