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/CakePHP 3.8

Interface CollectionInterface

Describes the methods a Collection should implement. A collection is an immutable list of elements exposing a number of traversing and extracting method for generating other collections.

Cake\Collection\CollectionInterface implements Iterator, JsonSerializable

Direct Implementers

Indirect Implementers

Method Summary

  • append() public

    Returns a new collection as the result of concatenating the list of elements in this collection with the passed list of elements

  • avg() public

    Returns the average of all the values extracted with $matcher or of this collection.

  • buffered() public

    Returns a new collection where the operations performed by this collection. No matter how many times the new collection is iterated, those operations will only be performed once.

  • chunk() public
    Breaks the collection into smaller arrays of the given size.
  • Breaks the collection into smaller arrays of the given size.
  • combine() public

    Returns a new collection where the values extracted based on a value path and then indexed by a key path. Optionally this method can produce parent groups based on a group property path.

  • compile() public

    Iterates once all elements in this collection and executes all stacked operations of them, finally it returns a new collection with the result. This is useful for converting non-rewindable internal iterators into a collection that can be rewound and used multiple times.

  • contains() public

    Returns true if $value is present in this collection. Comparisons are made both by value and type.

  • count() public
    Returns the amount of elements in the collection.
  • countBy() public

    Sorts a list into groups and returns a count for the number of elements in each group. Similar to groupBy, but instead of returning a list of values, returns a count for the number of values in that group.

  • countKeys() public

    Returns the number of unique keys in this iterator. This is, the number of elements the collection will contain after calling toArray()

  • each() public

    Executes the passed callable for each of the elements in this collection and passes both the value and key for them on each step. Returns the same collection for chaining.

  • every() public

    Returns true if all values in this collection pass the truth test provided in the callback.

  • extract() public

    Returns a new collection containing the column or property value found in each of the elements, as requested in the $matcher param.

  • filter() public

    Looks through each value in the collection, and returns another collection with all the values that pass a truth test. Only the values for which the callback returns true will be present in the resulting collection.

  • first() public
    Returns the first result in this collection
  • firstMatch() public

    Returns the first result matching all of the key-value pairs listed in conditions.

  • groupBy() public

    Splits a collection into sets, grouped by the result of running each value through the callback. If $callback is a string instead of a callable, groups by the property named by $callback on each of the values.

  • indexBy() public

    Given a list and a callback function that returns a key for each element in the list (or a property name), returns an object with an index of each item. Just like groupBy, but for when you know your keys are unique.

  • insert() public

    Returns a new collection containing each of the elements found in $values as a property inside the corresponding elements in this collection. The property where the values will be inserted is described by the $path parameter.

  • isEmpty() public
    Returns whether or not there are elements in this collection
  • Convert a result set into JSON.
  • last() public
    Returns the last result in this collection
  • lazy() public

    Returns a new collection where any operations chained after it are guaranteed to be run lazily. That is, elements will be yieleded one at a time.

  • listNested() public

    Returns a new collection with each of the elements of this collection after flattening the tree structure. The tree structure is defined by nesting elements under a key with a known name. It is possible to specify such name by using the '$nestingKey' parameter.

  • map() public

    Returns another collection after modifying each of the values in this one using the provided callable.

  • match() public

    Looks through each value in the list, returning a Collection of all the values that contain all of the key-value pairs listed in $conditions.

  • max() public

    Returns the top element in this collection after being sorted by a property. Check the sortBy method for information on the callback and $type parameters

  • median() public

    Returns the median of all the values extracted with $matcher or of this collection.

  • min() public

    Returns the bottom element in this collection after being sorted by a property. Check the sortBy method for information on the callback and $type parameters

  • nest() public

    Returns a new collection where the values are nested in a tree-like structure based on an id property path and a parent id property path.

  • reduce() public

    Folds the values in this collection to a single value, as the result of applying the callback function to all elements. $zero is the initial state of the reduction, and each successive step of it should be returned by the callback function. If $zero is omitted the first value of the collection will be used in its place and reduction will start from the second item.

  • reject() public

    Looks through each value in the collection, and returns another collection with all the values that do not pass a truth test. This is the opposite of filter.

  • sample() public

    Returns a new collection with maximum $size random elements from this collection

  • shuffle() public

    Returns a new collection with the elements placed in a random order, this function does not preserve the original keys in the collection.

  • skip() public

    Returns a new collection that will skip the specified amount of elements at the beginning of the iteration.

  • some() public

    Returns true if any of the values in this collection pass the truth test provided in the callback.

  • sortBy() public

    Returns a sorted iterator out of the elements in this collection, ranked in ascending order by the results of running each value through a callback. $callback can also be a string representing the column or property name.

  • stopWhen() public

    Creates a new collection that when iterated will stop yielding results if the provided condition evaluates to true.

  • sumOf() public

    Returns the total sum of all the values extracted with $matcher or of this collection.

  • take() public

    Returns a new collection with maximum $size elements in the internal order this collection was created. If a second parameter is passed, it will determine from what position to start taking elements.

  • takeLast() public
    Returns the last N elements of a collection
  • through() public

    Passes this collection through a callable as its first argument. This is useful for decorating the full collection with another object.

  • toArray() public
    Returns an array representation of the results
  • toList() public

    Returns an numerically-indexed array representation of the results. This is equivalent to calling toArray(false)

  • transpose() public
    Transpose rows and columns into columns and rows
  • unfold() public

    Creates a new collection where the items are the concatenation of the lists of items generated by the transformer function applied to each item in the original collection.

  • unwrap() public

    Returns the closest nested iterator that can be safely traversed without losing any possible transformations. This is used mainly to remove empty IteratorIterator wrappers that can only slowdown the iteration process.

  • zip() public

    Combines the elements of this collection with each of the elements of the passed iterables, using their positional index as a reference.

  • zipWith() public

    Combines the elements of this collection with each of the elements of the passed iterables, using their positional index as a reference.

Method Detail

append()source public

append( array|Traversable $items )

Returns a new collection as the result of concatenating the list of elements in this collection with the passed list of elements

Parameters

array|Traversable $items
Items list.

Returns

Cake\Collection\CollectionInterface

avg()source public

avg( string|callable|null $matcher = null )

Returns the average of all the values extracted with $matcher or of this collection.

Example:

$items = [
 ['invoice' => ['total' => 100]],
 ['invoice' => ['total' => 200]]
];

$total = (new Collection($items))->avg('invoice.total');

// Total: 150

$total = (new Collection([1, 2, 3]))->avg();
// Total: 2

Parameters

string|callable|null $matcher optional null

The property name to sum or a function If no value is passed, an identity function will be used. that will return the value of the property to sum.

Returns

float|integer|null

buffered()source public

buffered( )

Returns a new collection where the operations performed by this collection. No matter how many times the new collection is iterated, those operations will only be performed once.

This can also be used to make any non-rewindable iterator rewindable.

Returns

Cake\Collection\CollectionInterface

chunk()source public

chunk( integer $chunkSize )

Breaks the collection into smaller arrays of the given size.

Example:

$items [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
$chunked = (new Collection($items))->chunk(3)->toList();
// Returns [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11]]

Parameters

integer $chunkSize
The maximum size for each chunk

Returns

Cake\Collection\CollectionInterface

chunkWithKeys()source public

chunkWithKeys( integer $chunkSize , boolean $preserveKeys = true )

Breaks the collection into smaller arrays of the given size.

Example:

$items ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' => 6];
$chunked = (new Collection($items))->chunkWithKeys(3)->toList();
// Returns [['a' => 1, 'b' => 2, 'c' => 3], ['d' => 4, 'e' => 5, 'f' => 6]]

Parameters

integer $chunkSize
The maximum size for each chunk
boolean $preserveKeys optional true
If the keys of the array should be preserved

Returns

Cake\Collection\CollectionInterface

combine()source public

combine( callable|string $keyPath , callable|string $valuePath , callable|string|null $groupPath = null )

Returns a new collection where the values extracted based on a value path and then indexed by a key path. Optionally this method can produce parent groups based on a group property path.

Examples:

$items = [
 ['id' => 1, 'name' => 'foo', 'parent' => 'a'],
 ['id' => 2, 'name' => 'bar', 'parent' => 'b'],
 ['id' => 3, 'name' => 'baz', 'parent' => 'a'],
];

$combined = (new Collection($items))->combine('id', 'name');

// Result will look like this when converted to array
[
 1 => 'foo',
 2 => 'bar',
 3 => 'baz',
];

$combined = (new Collection($items))->combine('id', 'name', 'parent');

// Result will look like this when converted to array
[
 'a' => [1 => 'foo', 3 => 'baz'],
 'b' => [2 => 'bar']
];

Parameters

callable|string $keyPath

the column name path to use for indexing or a function returning the indexing key out of the provided element

callable|string $valuePath

the column name path to use as the array value or a function returning the value out of the provided element

callable|string|null $groupPath optional null

the column name path to use as the parent grouping key or a function returning the key out of the provided element

Returns

Cake\Collection\CollectionInterface

compile()source public

compile( boolean $preserveKeys = true )

Iterates once all elements in this collection and executes all stacked operations of them, finally it returns a new collection with the result. This is useful for converting non-rewindable internal iterators into a collection that can be rewound and used multiple times.

A common use case is to re-use the same variable for calculating different data. In those cases it may be helpful and more performant to first compile a collection and then apply more operations to it.

Example:

$collection->map($mapper)->sortBy('age')->extract('name');
$compiled = $collection->compile();
$isJohnHere = $compiled->some($johnMatcher);
$allButJohn = $compiled->filter($johnMatcher);

In the above example, had the collection not been compiled before, the iterations for map, sortBy and extract would've been executed twice: once for getting $isJohnHere and once for $allButJohn

You can think of this method as a way to create save points for complex calculations in a collection.

Parameters

boolean $preserveKeys optional true

whether to use the keys returned by this collection as the array keys. Keep in mind that it is valid for iterators to return the same key for different elements, setting this value to false can help getting all items if keys are not important in the result.

Returns

Cake\Collection\CollectionInterface

contains()source public

contains( mixed $value )

Returns true if $value is present in this collection. Comparisons are made both by value and type.

Parameters

mixed $value
The value to check for

Returns

boolean
true if $value is present in this collection

count()source public

count( )

Returns the amount of elements in the collection.

WARNINGS:

Consumes all elements for NoRewindIterator collections:

On certain type of collections, calling this method may render unusable afterwards. That is, you may not be able to get elements out of it, or to iterate on it anymore.

Specifically any collection wrapping a Generator (a function with a yield statement) or a unbuffered database cursor will not accept any other function calls after calling count() on it.

Create a new collection with buffered() method to overcome this problem.

Can report more elements than unique keys:

Any collection constructed by appending collections together, or by having internal iterators returning duplicate keys, will report a larger amount of elements using this functions than the final amount of elements when converting the collections to a keyed array. This is because duplicate keys will be collapsed into a single one in the final array, whereas this count method is only concerned by the amount of elements after converting it to a plain list.

If you need the count of elements after taking the keys in consideration (the count of unique keys), you can call countKeys()

Will change the current position of the iterator:

Calling this method at the same time that you are iterating this collections, for example in a foreach, will result in undefined behavior. Avoid doing this.

Returns

integer

countBy()source public

countBy( callable|string $callback )

Sorts a list into groups and returns a count for the number of elements in each group. Similar to groupBy, but instead of returning a list of values, returns a count for the number of values in that group.

When $callback is a string it should be a property name to extract or a dot separated path of properties that should be followed to get the last one in the path.

Example:

$items = [
 ['id' => 1, 'name' => 'foo', 'parent_id' => 10],
 ['id' => 2, 'name' => 'bar', 'parent_id' => 11],
 ['id' => 3, 'name' => 'baz', 'parent_id' => 10],
];

$group = (new Collection($items))->countBy('parent_id');

// Or
$group = (new Collection($items))->countBy(function ($e) {
 return $e['parent_id'];
});

// Result will look like this when converted to array
[
 10 => 2,
 11 => 1
];

Parameters

callable|string $callback

the callback or column name to use for indexing or a function returning the indexing key out of the provided element

Returns

Cake\Collection\CollectionInterface

countKeys()source public

countKeys( )

Returns the number of unique keys in this iterator. This is, the number of elements the collection will contain after calling toArray()

This method comes with a number of caveats. Please refer to CollectionInterface::count() for details.

Returns

integer

See

\Cake\Collection\CollectionInterface::count()

each()source public

each( callable $c )

Executes the passed callable for each of the elements in this collection and passes both the value and key for them on each step. Returns the same collection for chaining.

Example:

$collection = (new Collection($items))->each(function ($value, $key) {
 echo "Element $key: $value";
});

Parameters

callable $c

callable function that will receive each of the elements in this collection

Returns

Cake\Collection\CollectionInterface

every()source public

every( callable $c )

Returns true if all values in this collection pass the truth test provided in the callback.

Each time the callback is executed it will receive the value of the element in the current iteration and the key of the element as arguments, in that order.

Example:

$overTwentyOne = (new Collection([24, 45, 60, 15]))->every(function ($value, $key) {
 return $value > 21;
});

Empty collections always return true because it is a vacuous truth.

Parameters

callable $c
a callback function

Returns

boolean

true if for all elements in this collection the provided callback returns true, false otherwise.


extract()source public

extract( string $matcher )

Returns a new collection containing the column or property value found in each of the elements, as requested in the $matcher param.

The matcher can be a string with a property name to extract or a dot separated path of properties that should be followed to get the last one in the path.

If a column or property could not be found for a particular element in the collection, that position is filled with null.

Example:

Extract the user name for all comments in the array:

$items = [
 ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark']],
 ['comment' => ['body' => 'very cool', 'user' => ['name' => 'Renan']]
];
$extracted = (new Collection($items))->extract('comment.user.name');

// Result will look like this when converted to array
['Mark', 'Renan']

It is also possible to extract a flattened collection out of nested properties

$items = [
     ['comment' => ['votes' => [['value' => 1], ['value' => 2], ['value' => 3]]],
     ['comment' => ['votes' => [['value' => 4]]
];
$extracted = (new Collection($items))->extract('comment.votes.{*}.value');

// Result will contain
[1, 2, 3, 4]

Parameters

string $matcher

a dot separated string symbolizing the path to follow inside the hierarchy of each value so that the column can be extracted.

Returns

Cake\Collection\CollectionInterface

filter()source public

filter( callable $c = null )

Looks through each value in the collection, and returns another collection with all the values that pass a truth test. Only the values for which the callback returns true will be present in the resulting collection.

Each time the callback is executed it will receive the value of the element in the current iteration, the key of the element and this collection as arguments, in that order.

Example:

Filtering odd numbers in an array, at the end only the value 2 will be present in the resulting collection:

$collection = (new Collection([1, 2, 3]))->filter(function ($value, $key) {
 return $value % 2 === 0;
});

Parameters

callable $c optional null

the method that will receive each of the elements and returns true whether or not they should be in the resulting collection. If left null, a callback that filters out falsey values will be used.

Returns

Cake\Collection\CollectionInterface

first()source public

first( )

Returns the first result in this collection

Returns

mixed
The first value in the collection will be returned.

firstMatch()source public

firstMatch( array $conditions )

Returns the first result matching all of the key-value pairs listed in conditions.

Parameters

array $conditions

a key-value list of conditions where the key is a property path as accepted by Collection::extract, and the value the condition against with each element will be matched

Returns

mixed

See

\Cake\Collection\CollectionInterface::match()

groupBy()source public

groupBy( callable|string $callback )

Splits a collection into sets, grouped by the result of running each value through the callback. If $callback is a string instead of a callable, groups by the property named by $callback on each of the values.

When $callback is a string it should be a property name to extract or a dot separated path of properties that should be followed to get the last one in the path.

Example:

$items = [
 ['id' => 1, 'name' => 'foo', 'parent_id' => 10],
 ['id' => 2, 'name' => 'bar', 'parent_id' => 11],
 ['id' => 3, 'name' => 'baz', 'parent_id' => 10],
];

$group = (new Collection($items))->groupBy('parent_id');

// Or
$group = (new Collection($items))->groupBy(function ($e) {
 return $e['parent_id'];
});

// Result will look like this when converted to array
[
 10 => [
     ['id' => 1, 'name' => 'foo', 'parent_id' => 10],
     ['id' => 3, 'name' => 'baz', 'parent_id' => 10],
 ],
 11 => [
     ['id' => 2, 'name' => 'bar', 'parent_id' => 11],
 ]
];

Parameters

callable|string $callback

the callback or column name to use for grouping or a function returning the grouping key out of the provided element

Returns

Cake\Collection\CollectionInterface

indexBy()source public

indexBy( callable|string $callback )

Given a list and a callback function that returns a key for each element in the list (or a property name), returns an object with an index of each item. Just like groupBy, but for when you know your keys are unique.

When $callback is a string it should be a property name to extract or a dot separated path of properties that should be followed to get the last one in the path.

Example:

$items = [
 ['id' => 1, 'name' => 'foo'],
 ['id' => 2, 'name' => 'bar'],
 ['id' => 3, 'name' => 'baz'],
];

$indexed = (new Collection($items))->indexBy('id');

// Or
$indexed = (new Collection($items))->indexBy(function ($e) {
 return $e['id'];
});

// Result will look like this when converted to array
[
 1 => ['id' => 1, 'name' => 'foo'],
 3 => ['id' => 3, 'name' => 'baz'],
 2 => ['id' => 2, 'name' => 'bar'],
];

Parameters

callable|string $callback

the callback or column name to use for indexing or a function returning the indexing key out of the provided element

Returns

Cake\Collection\CollectionInterface

insert()source public

insert( string $path , mixed $values )

Returns a new collection containing each of the elements found in $values as a property inside the corresponding elements in this collection. The property where the values will be inserted is described by the $path parameter.

The $path can be a string with a property name or a dot separated path of properties that should be followed to get the last one in the path.

If a column or property could not be found for a particular element in the collection as part of the path, the element will be kept unchanged.

Example:

Insert ages into a collection containing users:

$items = [
 ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark']],
 ['comment' => ['body' => 'awesome', 'user' => ['name' => 'Renan']]
];
$ages = [25, 28];
$inserted = (new Collection($items))->insert('comment.user.age', $ages);

// Result will look like this when converted to array
[
 ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark', 'age' => 25]],
 ['comment' => ['body' => 'awesome', 'user' => ['name' => 'Renan', 'age' => 28]]
];

Parameters

string $path

a dot separated string symbolizing the path to follow inside the hierarchy of each value so that the value can be inserted

mixed $values

The values to be inserted at the specified path, values are matched with the elements in this collection by its positional index.

Returns

Cake\Collection\CollectionInterface

isEmpty()source public

isEmpty( )

Returns whether or not there are elements in this collection

Example:

$items [1, 2, 3];
(new Collection($items))->isEmpty(); // false
(new Collection([]))->isEmpty(); // true

Returns

boolean

jsonSerialize()source public

jsonSerialize( )

Convert a result set into JSON.

Part of JsonSerializable interface.

Returns

array
The data to convert to JSON

Implementation of

JsonSerializable::jsonSerialize()

last()source public

last( )

Returns the last result in this collection

Returns

mixed
The last value in the collection will be returned.

lazy()source public

lazy( )

Returns a new collection where any operations chained after it are guaranteed to be run lazily. That is, elements will be yieleded one at a time.

A lazy collection can only be iterated once. A second attempt results in an error.

Returns

Cake\Collection\CollectionInterface

listNested()source public

listNested( string|integer $dir = 'desc' , string|callable $nestingKey = 'children' )

Returns a new collection with each of the elements of this collection after flattening the tree structure. The tree structure is defined by nesting elements under a key with a known name. It is possible to specify such name by using the '$nestingKey' parameter.

By default all elements in the tree following a Depth First Search will be returned, that is, elements from the top parent to the leaves for each branch.

It is possible to return all elements from bottom to top using a Breadth First Search approach by passing the '$dir' parameter with 'asc'. That is, it will return all elements for the same tree depth first and from bottom to top.

Finally, you can specify to only get a collection with the leaf nodes in the tree structure. You do so by passing 'leaves' in the first argument.

The possible values for the first argument are aliases for the following constants and it is valid to pass those instead of the alias:

  • desc: TreeIterator::SELF_FIRST
  • asc: TreeIterator::CHILD_FIRST
  • leaves: TreeIterator::LEAVES_ONLY

Example:

$collection = new Collection([
 ['id' => 1, 'children' => [['id' => 2, 'children' => [['id' => 3]]]]],
 ['id' => 4, 'children' => [['id' => 5]]]
]);
$flattenedIds = $collection->listNested()->extract('id'); // Yields [1, 2, 3, 4, 5]

Parameters

string|integer $dir optional 'desc'
The direction in which to return the elements
string|callable $nestingKey optional 'children'

The key name under which children are nested or a callable function that will return the children list

Returns

Cake\Collection\CollectionInterface

map()source public

map( callable $c )

Returns another collection after modifying each of the values in this one using the provided callable.

Each time the callback is executed it will receive the value of the element in the current iteration, the key of the element and this collection as arguments, in that order.

Example:

Getting a collection of booleans where true indicates if a person is female:

$collection = (new Collection($people))->map(function ($person, $key) {
 return $person->gender === 'female';
});

Parameters

callable $c

the method that will receive each of the elements and returns the new value for the key that is being iterated

Returns

Cake\Collection\CollectionInterface

match()source public

match( array $conditions )

Looks through each value in the list, returning a Collection of all the values that contain all of the key-value pairs listed in $conditions.

Example:

$items = [
 ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark']],
 ['comment' => ['body' => 'very cool', 'user' => ['name' => 'Renan']]
];

$extracted = (new Collection($items))->match(['user.name' => 'Renan']);

// Result will look like this when converted to array
[
 ['comment' => ['body' => 'very cool', 'user' => ['name' => 'Renan']]
]

Parameters

array $conditions

a key-value list of conditions where the key is a property path as accepted by `Collection::extract, and the value the condition against with each element will be matched

Returns

Cake\Collection\CollectionInterface

max()source public

max( callable|string $callback , integer $type = \SORT_NUMERIC )

Returns the top element in this collection after being sorted by a property. Check the sortBy method for information on the callback and $type parameters

Examples:

// For a collection of employees
$max = $collection->max('age');
$max = $collection->max('user.salary');
$max = $collection->max(function ($e) {
 return $e->get('user')->get('salary');
});

// Display employee name
echo $max->name;

Parameters

callable|string $callback
the callback or column name to use for sorting
integer $type optional \SORT_NUMERIC

the type of comparison to perform, either SORT_STRING SORT_NUMERIC or SORT_NATURAL

Returns

mixed
The value of the top element in the collection

See

\Cake\Collection\CollectionIterface::sortBy()

median()source public

median( string|callable|null $matcher = null )

Returns the median of all the values extracted with $matcher or of this collection.

Example:

$items = [
 ['invoice' => ['total' => 400]],
 ['invoice' => ['total' => 500]]
 ['invoice' => ['total' => 100]]
 ['invoice' => ['total' => 333]]
 ['invoice' => ['total' => 200]]
];

$total = (new Collection($items))->median('invoice.total');

// Total: 333

$total = (new Collection([1, 2, 3, 4]))->median();
// Total: 2.5

Parameters

string|callable|null $matcher optional null

The property name to sum or a function If no value is passed, an identity function will be used. that will return the value of the property to sum.

Returns

float|integer|null

min()source public

min( callable|string $callback , integer $type = \SORT_NUMERIC )

Returns the bottom element in this collection after being sorted by a property. Check the sortBy method for information on the callback and $type parameters

Examples:

// For a collection of employees
$min = $collection->min('age');
$min = $collection->min('user.salary');
$min = $collection->min(function ($e) {
 return $e->get('user')->get('salary');
});

// Display employee name
echo $min->name;

Parameters

callable|string $callback
the callback or column name to use for sorting
integer $type optional \SORT_NUMERIC

the type of comparison to perform, either SORT_STRING SORT_NUMERIC or SORT_NATURAL

Returns

mixed
The value of the bottom element in the collection

See

\Cake\Collection\CollectionInterface::sortBy()

nest()source public

nest( callable|string $idPath , callable|string $parentPath , string $nestingKey = 'children' )

Returns a new collection where the values are nested in a tree-like structure based on an id property path and a parent id property path.

Parameters

callable|string $idPath

the column name path to use for determining whether an element is parent of another

callable|string $parentPath

the column name path to use for determining whether an element is child of another

string $nestingKey optional 'children'
The key name under which children are nested

Returns

Cake\Collection\CollectionInterface

reduce()source public

reduce( callable $c , mixed $zero = null )

Folds the values in this collection to a single value, as the result of applying the callback function to all elements. $zero is the initial state of the reduction, and each successive step of it should be returned by the callback function. If $zero is omitted the first value of the collection will be used in its place and reduction will start from the second item.

Parameters

callable $c
The callback function to be called
mixed $zero optional null
The state of reduction

Returns

mixed

reject()source public

reject( callable $c )

Looks through each value in the collection, and returns another collection with all the values that do not pass a truth test. This is the opposite of filter.

Each time the callback is executed it will receive the value of the element in the current iteration, the key of the element and this collection as arguments, in that order.

Example:

Filtering even numbers in an array, at the end only values 1 and 3 will be present in the resulting collection:

$collection = (new Collection([1, 2, 3]))->reject(function ($value, $key) {
 return $value % 2 === 0;
});

Parameters

callable $c

the method that will receive each of the elements and returns true whether or not they should be out of the resulting collection.

Returns

Cake\Collection\CollectionInterface

sample()source public

sample( integer $size = 10 )

Returns a new collection with maximum $size random elements from this collection

Parameters

integer $size optional 10

the maximum number of elements to randomly take from this collection

Returns

Cake\Collection\CollectionInterface

shuffle()source public

shuffle( )

Returns a new collection with the elements placed in a random order, this function does not preserve the original keys in the collection.

Returns

Cake\Collection\CollectionInterface

skip()source public

skip( integer $howMany )

Returns a new collection that will skip the specified amount of elements at the beginning of the iteration.

Parameters

integer $howMany
The number of elements to skip.

Returns

Cake\Collection\CollectionInterface

some()source public

some( callable $c )

Returns true if any of the values in this collection pass the truth test provided in the callback.

Each time the callback is executed it will receive the value of the element in the current iteration and the key of the element as arguments, in that order.

Example:

$hasYoungPeople = (new Collection([24, 45, 15]))->every(function ($value, $key) {
 return $value < 21;
});

Parameters

callable $c
a callback function

Returns

boolean

true if the provided callback returns true for any element in this collection, false otherwise


sortBy()source public

sortBy( callable|string $callback , integer $dir = SORT_DESC , integer $type = \SORT_NUMERIC )

Returns a sorted iterator out of the elements in this collection, ranked in ascending order by the results of running each value through a callback. $callback can also be a string representing the column or property name.

The callback will receive as its first argument each of the elements in $items, the value returned by the callback will be used as the value for sorting such element. Please note that the callback function could be called more than once per element.

Example:

$items = $collection->sortBy(function ($user) {
 return $user->age;
});

// alternatively
$items = $collection->sortBy('age');

// or use a property path
$items = $collection->sortBy('department.name');

// output all user name order by their age in descending order
foreach ($items as $user) {
 echo $user->name;
}

Parameters

callable|string $callback
the callback or column name to use for sorting
integer $dir optional SORT_DESC
either SORT_DESC or SORT_ASC
integer $type optional \SORT_NUMERIC

the type of comparison to perform, either SORT_STRING SORT_NUMERIC or SORT_NATURAL

Returns

Cake\Collection\CollectionInterface

stopWhen()source public

stopWhen( callable $condition )

Creates a new collection that when iterated will stop yielding results if the provided condition evaluates to true.

This is handy for dealing with infinite iterators or any generator that could start returning invalid elements at a certain point. For example, when reading lines from a file stream you may want to stop the iteration after a certain value is reached.

Example:

Get an array of lines in a CSV file until the timestamp column is less than a date

$lines = (new Collection($fileLines))->stopWhen(function ($value, $key) {
 return (new DateTime($value))->format('Y') < 2012;
})
->toArray();

Get elements until the first unapproved message is found:

$comments = (new Collection($comments))->stopWhen(['is_approved' => false]);

Parameters

callable $condition

the method that will receive each of the elements and returns true when the iteration should be stopped. If an array, it will be interpreted as a key-value list of conditions where the key is a property path as accepted by Collection::extract, and the value the condition against with each element will be matched.

Returns

Cake\Collection\CollectionInterface

sumOf()source public

sumOf( string|callable|null $matcher = null )

Returns the total sum of all the values extracted with $matcher or of this collection.

Example:

$items = [
 ['invoice' => ['total' => 100]],
 ['invoice' => ['total' => 200]]
];

$total = (new Collection($items))->sumOf('invoice.total');

// Total: 300

$total = (new Collection([1, 2, 3]))->sumOf();
// Total: 6

Parameters

string|callable|null $matcher optional null

The property name to sum or a function If no value is passed, an identity function will be used. that will return the value of the property to sum.

Returns

float|integer

take()source public

take( integer $size = 1 , integer $from = 0 )

Returns a new collection with maximum $size elements in the internal order this collection was created. If a second parameter is passed, it will determine from what position to start taking elements.

Parameters

integer $size optional 1

the maximum number of elements to take from this collection

integer $from optional 0
A positional offset from where to take the elements

Returns

Cake\Collection\CollectionInterface

takeLast()source public

takeLast( integer $howMany )

Returns the last N elements of a collection

Example:

$items = [1, 2, 3, 4, 5];

$last = (new Collection($items))->takeLast(3);

// Result will look like this when converted to array
[3, 4, 5];

Parameters

integer $howMany
The number of elements at the end of the collection

Returns

Cake\Collection\CollectionInterface

through()source public

through( callable $handler )

Passes this collection through a callable as its first argument. This is useful for decorating the full collection with another object.

Example:

$items = [1, 2, 3];
$decorated = (new Collection($items))->through(function ($collection) {
     return new MyCustomCollection($collection);
});

Parameters

callable $handler

A callable function that will receive this collection as first argument.

Returns

Cake\Collection\CollectionInterface

toArray()source public

toArray( boolean $preserveKeys = true )

Returns an array representation of the results

Parameters

boolean $preserveKeys optional true

whether to use the keys returned by this collection as the array keys. Keep in mind that it is valid for iterators to return the same key for different elements, setting this value to false can help getting all items if keys are not important in the result.

Returns

array

toList()source public

toList( )

Returns an numerically-indexed array representation of the results. This is equivalent to calling toArray(false)

Returns

array

transpose()source public

transpose( )

Transpose rows and columns into columns and rows

Example:

$items = [
      ['Products', '2012', '2013', '2014'],
      ['Product A', '200', '100', '50'],
      ['Product B', '300', '200', '100'],
      ['Product C', '400', '300', '200'],
]

$transpose = (new Collection($items))->transpose()->toList();

// Returns
// [
//     ['Products', 'Product A', 'Product B', 'Product C'],
//     ['2012', '200', '300', '400'],
//     ['2013', '100', '200', '300'],
//     ['2014', '50', '100', '200'],
// ]

Returns

Cake\Collection\CollectionInterface

unfold()source public

unfold( callable $transformer = null )

Creates a new collection where the items are the concatenation of the lists of items generated by the transformer function applied to each item in the original collection.

The transformer function will receive the value and the key for each of the items in the collection, in that order, and it must return an array or a Traversable object that can be concatenated to the final result.

If no transformer function is passed, an "identity" function will be used. This is useful when each of the elements in the source collection are lists of items to be appended one after another.

Example:

$items [[1, 2, 3], [4, 5]];
$unfold = (new Collection($items))->unfold(); // Returns [1, 2, 3, 4, 5]

Using a transformer

$items [1, 2, 3];
$allItems = (new Collection($items))->unfold(function ($page) {
 return $service->fetchPage($page)->toArray();
});

Parameters

callable $transformer optional null

A callable function that will receive each of the items in the collection and should return an array or Traversable object

Returns

Cake\Collection\CollectionInterface

unwrap()source public

unwrap( )

Returns the closest nested iterator that can be safely traversed without losing any possible transformations. This is used mainly to remove empty IteratorIterator wrappers that can only slowdown the iteration process.

Returns

Traversable

zip()source public

zip( array|Traversable $items )

Combines the elements of this collection with each of the elements of the passed iterables, using their positional index as a reference.

Example:

$collection = new Collection([1, 2]);
$collection->zip([3, 4], [5, 6])->toList(); // returns [[1, 3, 5], [2, 4, 6]]

Parameters

array|Traversable $items
$items The collections to zip.

Returns

Cake\Collection\CollectionInterface

zipWith()source public

zipWith( array|Traversable $items , callable $callable )

Combines the elements of this collection with each of the elements of the passed iterables, using their positional index as a reference.

The resulting element will be the return value of the $callable function.

Example:

$collection = new Collection([1, 2]);
$zipped = $collection->zipWith([3, 4], [5, 6], function (...$args) {
  return array_sum($args);
});
$zipped->toList(); // returns [9, 12]; [(1 + 3 + 5), (2 + 4 + 6)]

Parameters

array|Traversable $items
$items The collections to zip.
callable $callable
The function to use for zipping the elements together.

Returns

Cake\Collection\CollectionInterface

Magic methods summary

cartesianProduct()source public

cartesianProduct( callable $operation = , callable $filter = )

Parameters

callable $operation optional
callable $filter optional

Returns

Cake\Collection\CollectionInterface

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https://api.cakephp.org/3.8/class-Cake.Collection.CollectionInterface.html