PHP - Check if value exists in array but only for specific key

Question

I have an array and I am checking if a value exists in the array using in_array(). However, I want to check only in the ID key and not date.

$arr = ({
    "ID":"10",
    "date":"04\/22\/20"
},
{
    "ID":"20",
    "date":"05\/25\/20"
},
{
    "ID":"32",
    "date":"07\/13\/20"
});

So in this example, the condition should not be met since 25 exists in date, but not in ID.

if (in_array("25", $arr)) {
    return true;
}

Shortcut way could be passing array_column() result to the in_array() function. Like, in_array("25", array_column($arr, 'ID')). Clean, yes. Efficient, not much. — Sohel Aman
– Sohel Aman, Commented Jul 13, 2020 at 17:24

Alice Ryhl · Accepted Answer · 2020-07-13 17:30:14Z

1

To directly do this, you need to loop over the array.

function hasId($arr, $id) {
    foreach ($arr as $value) {
        if ($value['ID'] == $id) return true;
    }
    return false;
}

If you need to do this for several IDs, it is better to convert the array to a map and use isset.

$map = array();
foreach ($arr as $value) {
    $map[$value['ID']] = $value;
    // or $map[$value['ID']] = $value['date'];
}

if (isset($map["25"])) {
    ...
}

This will also allow you to look up any value in the map cheaply by id using $map[$key].

edited Jul 13, 2020 at 17:30

answered Jul 13, 2020 at 17:17

Alice Ryhl

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Comments

Ankit Jindal · Accepted Answer · 2020-07-13 17:55:01Z

1

For versions of PHP (>= 5.5.0), there is a simple way to do this

$arr = ({
    "ID":"10",
    "date":"04\/22\/20"
},
{
    "ID":"20",
    "date":"05\/25\/20"
},
{
    "ID":"32",
    "date":"07\/13\/20"
});

$searched_value = array_search('25', array_column($arr, 'ID'));

Here is documentation for array_column.

answered Jul 13, 2020 at 17:55

Ankit Jindal

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Comments

Jumshud · Accepted Answer · 2020-07-13 17:21:49Z

0

You can also check it by array_filter function:

$searchId = '25';
$arr = [[
    "ID" => "10",
    "date" => "04\/22\/20"
],
[
    "ID" => "25",
    "date" => "05\/25\/20"
],
[
    "ID" => "32",
    "date" => "07\/13\/20"
]];

$items = array_filter($arr, function ($item) use ($searchId) { 
    return $item['ID'] === $searchId;
});

if (count($items) > 0) {
   echo 'found';
};

answered Jul 13, 2020 at 17:21

Jumshud

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2 Comments

Alice Ryhl Over a year ago

This is more expensive than simply looping over the array, as it creates an entirely new array you do not need.

Jumshud Over a year ago

@AliceRyhl I have added also here) If just need to check the existence of the item then simple loop and return immediately would be efficient

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