ArrayHelper
Additionally to the rich set of PHP array functions, the Yii array helper provides extra static methods allowing you to deal with arrays more efficiently.
- Getting Values
- Setting values
- Take a value from an array
- Checking Existence of Keys
- Retrieving Columns
- Re-indexing Arrays
- Building Maps
- Multidimensional Sorting
- Detecting Array Types
- HTML Encoding and Decoding Values
- Merging Arrays
- Converting Objects to Arrays
- Testing against Arrays
Getting Values
Retrieving values from an array, an object or a complex structure consisting of both using standard PHP is quite repetitive. You have to check if key exists with isset
first, then if it does you're getting it, if not, providing default value:
class User
{
public $name = 'Alex';
}
$array = [
'foo' => [
'bar' => new User(),
]
];
$value = isset($array['foo']['bar']->name) ? $array['foo']['bar']->name : null;
Yii provides a very convenient method to do it:
$value = ArrayHelper::getValue($array, 'foo.bar.name');
First method argument is where we're getting value from. Second argument specifies how to get the data. It could be one of the following:
- Name of array key or object property to retrieve value from.
- Set of dot separated array keys or object property names. The one we've used in the example above.
- A callback returning a value.
The callback should be the following:
$fullName = ArrayHelper::getValue($user, function ($user, $defaultValue) {
return $user->firstName . ' ' . $user->lastName;
});
Third optional argument is default value which is null
if not specified. Could be used as follows:
$username = ArrayHelper::getValue($comment, 'user.username', 'Unknown');
Setting values
$array = [
'key' => [
'in' => ['k' => 'value']
]
];
ArrayHelper::setValue($array, 'key.in', ['arr' => 'val']);
// the path to write the value in `$array` can be specified as an array
ArrayHelper::setValue($array, ['key', 'in'], ['arr' => 'val']);
As a result, initial value of $array['key']['in']
will be overwritten by new value
[
'key' => [
'in' => ['arr' => 'val']
]
]
If the path contains a nonexistent key, it will be created
// if `$array['key']['in']['arr0']` is not empty, the value will be added to the array
ArrayHelper::setValue($array, 'key.in.arr0.arr1', 'val');
// if you want to completely override the value `$array['key']['in']['arr0']`
ArrayHelper::setValue($array, 'key.in.arr0', ['arr1' => 'val']);
The result will be
[
'key' => [
'in' => [
'k' => 'value',
'arr0' => ['arr1' => 'val']
]
]
]
Take a value from an array
In case you want to get a value and then immediately remove it from an array you can use remove
method:
$array = ['type' => 'A', 'options' => [1, 2]];
$type = ArrayHelper::remove($array, 'type');
After executing the code $array
will contain ['options' => [1, 2]]
and $type
will be A
. Note that unlike getValue
method, remove
supports simple key names only.
Checking Existence of Keys
ArrayHelper::keyExists
works the same way as array_key_exists except that it also supports case-insensitive key comparison. For example,
$data1 = [
'userName' => 'Alex',
];
$data2 = [
'username' => 'Carsten',
];
if (!ArrayHelper::keyExists('username', $data1, false) || !ArrayHelper::keyExists('username', $data2, false)) {
echo "Please provide username.";
}
Retrieving Columns
Often you need to get a column of values from array of data rows or objects. Common example is getting a list of IDs.
$array = [
['id' => '123', 'data' => 'abc'],
['id' => '345', 'data' => 'def'],
];
$ids = ArrayHelper::getColumn($array, 'id');
The result will be ['123', '345']
.
If additional transformations are required or the way of getting value is complex, second argument could be specified as an anonymous function:
$result = ArrayHelper::getColumn($array, function ($element) {
return $element['id'];
});
Re-indexing Arrays
In order to index an array according to a specified key, the index
method can be used. The input should be either multidimensional array or an array of objects. The $key
can be either a key name of the sub-array, a property name of object, or an anonymous function that must return the value that will be used as a key.
The $groups
attribute is an array of keys, that will be used to group the input array into one or more sub-arrays based on keys specified.
If the $key
attribute or its value for the particular element is null
and $groups
is not defined, the array element will be discarded. Otherwise, if $groups
is specified, array element will be added to the result array without any key.
For example:
$array = [
['id' => '123', 'data' => 'abc', 'device' => 'laptop'],
['id' => '345', 'data' => 'def', 'device' => 'tablet'],
['id' => '345', 'data' => 'hgi', 'device' => 'smartphone'],
];
$result = ArrayHelper::index($array, 'id');
The result will be an associative array, where the key is the value of id
attribute:
[
'123' => ['id' => '123', 'data' => 'abc', 'device' => 'laptop'],
'345' => ['id' => '345', 'data' => 'hgi', 'device' => 'smartphone']
// The second element of an original array is overwritten by the last element because of the same id
]
Anonymous function, passed as a $key
, gives the same result:
$result = ArrayHelper::index($array, function ($element) {
return $element['id'];
});
Passing id
as a third argument will group $array
by id
:
$result = ArrayHelper::index($array, null, 'id');
The result will be a multidimensional array grouped by id
on the first level and not indexed on the second level:
[
'123' => [
['id' => '123', 'data' => 'abc', 'device' => 'laptop']
],
'345' => [ // all elements with this index are present in the result array
['id' => '345', 'data' => 'def', 'device' => 'tablet'],
['id' => '345', 'data' => 'hgi', 'device' => 'smartphone'],
]
]
An anonymous function can be used in the grouping array as well:
$result = ArrayHelper::index($array, 'data', [function ($element) {
return $element['id'];
}, 'device']);
The result will be a multidimensional array grouped by id
on the first level, by device
on the second level and indexed by data
on the third level:
[
'123' => [
'laptop' => [
'abc' => ['id' => '123', 'data' => 'abc', 'device' => 'laptop']
]
],
'345' => [
'tablet' => [
'def' => ['id' => '345', 'data' => 'def', 'device' => 'tablet']
],
'smartphone' => [
'hgi' => ['id' => '345', 'data' => 'hgi', 'device' => 'smartphone']
]
]
]
Building Maps
In order to build a map (key-value pairs) from a multidimensional array or an array of objects you can use map
method. The $from
and $to
parameters specify the key names or property names to set up the map. Optionally, one can further group the map according to a grouping field $group
. For example,
$array = [
['id' => '123', 'name' => 'aaa', 'class' => 'x'],
['id' => '124', 'name' => 'bbb', 'class' => 'x'],
['id' => '345', 'name' => 'ccc', 'class' => 'y'],
];
$result = ArrayHelper::map($array, 'id', 'name');
// the result is:
// [
// '123' => 'aaa',
// '124' => 'bbb',
// '345' => 'ccc',
// ]
$result = ArrayHelper::map($array, 'id', 'name', 'class');
// the result is:
// [
// 'x' => [
// '123' => 'aaa',
// '124' => 'bbb',
// ],
// 'y' => [
// '345' => 'ccc',
// ],
// ]
Multidimensional Sorting
multisort
method helps to sort an array of objects or nested arrays by one or several keys. For example,
$data = [
['age' => 30, 'name' => 'Alexander'],
['age' => 30, 'name' => 'Brian'],
['age' => 19, 'name' => 'Barney'],
];
ArrayHelper::multisort($data, ['age', 'name'], [SORT_ASC, SORT_DESC]);
After sorting we'll get the following in $data
:
[
['age' => 19, 'name' => 'Barney'],
['age' => 30, 'name' => 'Brian'],
['age' => 30, 'name' => 'Alexander'],
];
Second argument that specifies keys to sort by can be a string if it's a single key, an array in case of multiple keys or an anonymous function like the following one:
ArrayHelper::multisort($data, function($item) {
// sort by age if it exists or by name otherwise
return isset($item['age']) ? $item['age'] : $item['name'];
});
Third argument is direction. In case of sorting by a single key it could be either SORT_ASC
or SORT_DESC
. If sorting by multiple values you can sort each value differently by providing an array of sort direction.
Last argument is PHP sort flag that could take the same values as the ones passed to PHP sort().
Detecting Array Types
It is handy to know whether an array is indexed or an associative. Here's an example:
// no keys specified
$indexed = ['Qiang', 'Paul'];
echo ArrayHelper::isIndexed($indexed);
// all keys are strings
$associative = ['framework' => 'Yii', 'version' => '2.0'];
echo ArrayHelper::isAssociative($associative);
HTML Encoding and Decoding Values
In order to encode or decode special characters in an array of strings into HTML entities you can use the following:
$encoded = ArrayHelper::htmlEncode($data);
$decoded = ArrayHelper::htmlDecode($data);
Only values will be encoded by default. By passing second argument as false
you can encode array's keys as well. Encoding will use application charset and could be changed via third argument.
Merging Arrays
You can use [[yii\helpers\ArrayHelper::merge()|ArrayHelper::merge()]] to merge two or more arrays into one recursively. If each array has an element with the same string key value, the latter will overwrite the former (different from array_merge_recursive()). Recursive merging will be conducted if both arrays have an element of array type and are having the same key. For integer-keyed elements, the elements from the latter array will be appended to the former array. You can use [[yii\helpers\UnsetArrayValue]] object to unset value from previous array or [[yii\helpers\ReplaceArrayValue]] to force replace former value instead of recursive merging.
For example:
$array1 = [
'name' => 'Yii',
'version' => '1.1',
'ids' => [
1,
],
'validDomains' => [
'example.com',
'www.example.com',
],
'emails' => [
'admin' => '[email protected]',
'dev' => '[email protected]',
],
];
$array2 = [
'version' => '2.0',
'ids' => [
2,
],
'validDomains' => new \yii\helpers\ReplaceArrayValue([
'yiiframework.com',
'www.yiiframework.com',
]),
'emails' => [
'dev' => new \yii\helpers\UnsetArrayValue(),
],
];
$result = ArrayHelper::merge($array1, $array2);
The result will be:
[
'name' => 'Yii',
'version' => '2.0',
'ids' => [
1,
2,
],
'validDomains' => [
'yiiframework.com',
'www.yiiframework.com',
],
'emails' => [
'admin' => '[email protected]',
],
]
Converting Objects to Arrays
Often you need to convert an object or an array of objects into an array. The most common case is converting active record models in order to serve data arrays via REST API or use it otherwise. The following code could be used to do it:
$posts = Post::find()->limit(10)->all();
$data = ArrayHelper::toArray($posts, [
'app\models\Post' => [
'id',
'title',
// the key name in array result => property name
'createTime' => 'created_at',
// the key name in array result => anonymous function
'length' => function ($post) {
return strlen($post->content);
},
],
]);
The first argument contains the data we want to convert. In our case we're converting a Post
AR model.
The second argument is conversion mapping per class. We're setting a mapping for Post
model. Each mapping array contains a set of mappings. Each mapping could be:
- A field name to include as is.
- A key-value pair of desired array key name and model column name to take value from.
- A key-value pair of desired array key name and a callback which returns value.
The result of conversion above for single model will be:
[
'id' => 123,
'title' => 'test',
'createTime' => '2013-01-01 12:00AM',
'length' => 301,
]
It is possible to provide default way of converting object to array for a specific class by implementing [[yii\base\Arrayable|Arrayable]] interface in that class.
Testing against Arrays
Often you need to check if an element is in an array or a set of elements is a subset of another. While PHP offers in_array()
, this does not support subsets or \Traversable
objects.
To aid these kinds of tests, [[yii\helpers\ArrayHelper]] provides [[yii\helpers\ArrayHelper::isIn()|isIn()]] and [[yii\helpers\ArrayHelper::isSubset()|isSubset()]] with the same signature as in_array().
// true
ArrayHelper::isIn('a', ['a']);
// true
ArrayHelper::isIn('a', new ArrayObject(['a']));
// true
ArrayHelper::isSubset(new ArrayObject(['a', 'c']), new ArrayObject(['a', 'b', 'c']));
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