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Array functions

AQL provides functions for higher-level array manipulation. Also see the numeric functions for functions that work on number arrays. If you want to concatenate the elements of an array equivalent to join() in JavaScript, see CONCAT() and CONCAT_SEPARATOR() in the string functions chapter.

Apart from that, AQL also offers several language constructs:

  • simple array access of individual elements,
  • array operators for array expansion and contraction, optionally with inline filter, limit and projection,
  • array comparison operators to compare each element in an array to a value or the elements of another array,
  • loop-based operations using FOR, SORT, LIMIT, as well as COLLECT for grouping, which also offers efficient aggregation.

APPEND()

APPEND(anyArray, values, unique) → newArray

Add all elements of an array to another array. All values are added at the end of the array (right side).

  • anyArray (array): array with elements of arbitrary type
  • values (array): array, whose elements shall be added to anyArray
  • unique (bool, optional): if set to true, only those values will be added that are not already contained in anyArray. The default is false.
  • returns newArray (array): the modified array

Examples

@startDocuBlockInline aqlArrayAppend_1 @EXAMPLE_AQL{aqlArrayAppend_1} RETURN APPEND([ 1, 2, 3 ], [ 5, 6, 9 ]) @END_EXAMPLE_AQL @endDocuBlock aqlArrayAppend_1

@startDocuBlockInline aqlArrayAppend_2 @EXAMPLE_AQL{aqlArrayAppend_2} RETURN APPEND([ 1, 2, 3 ], [ 3, 4, 5, 2, 9 ], true) @END_EXAMPLE_AQL @endDocuBlock aqlArrayAppend_2

COUNT()

This is an alias for LENGTH().

COUNT_DISTINCT()

COUNT_DISTINCT(anyArray) → number

Get the number of distinct elements in an array.

  • anyArray (array): array with elements of arbitrary type
  • returns number: the number of distinct elements in anyArray.

Examples

@startDocuBlockInline aqlArrayCountDistinct_1 @EXAMPLE_AQL{aqlArrayCountDistinct_1} RETURN COUNT_DISTINCT([ 1, 2, 3 ]) @END_EXAMPLE_AQL @endDocuBlock aqlArrayCountDistinct_1

@startDocuBlockInline aqlArrayCountDistinct_2 @EXAMPLE_AQL{aqlArrayCountDistinct_2} RETURN COUNT_DISTINCT([ "yes", "no", "yes", "sauron", "no", "yes" ]) @END_EXAMPLE_AQL @endDocuBlock aqlArrayCountDistinct_2

COUNT_UNIQUE()

This is an alias for COUNT_DISTINCT().

FIRST()

FIRST(anyArray) → firstElement

Get the first element of an array. It is the same as anyArray[0].

  • anyArray (array): array with elements of arbitrary type
  • returns firstElement (any|null): the first element of anyArray, or null if the array is empty.

Examples

@startDocuBlockInline aqlArrayFirst_1 @EXAMPLE_AQL{aqlArrayFirst_1} RETURN FIRST([ 1, 2, 3 ]) @END_EXAMPLE_AQL @endDocuBlock aqlArrayFirst_1

@startDocuBlockInline aqlArrayFirst_2 @EXAMPLE_AQL{aqlArrayFirst_2} RETURN FIRST([]) @END_EXAMPLE_AQL @endDocuBlock aqlArrayFirst_2

FLATTEN()

FLATTEN(anyArray, depth) → flatArray

Turn an array of arrays into a flat array. All array elements in array will be expanded in the result array. Non-array elements are added as they are. The function will recurse into sub-arrays up to the specified depth. Duplicates will not be removed.

  • array (array): array with elements of arbitrary type, including nested arrays
  • depth (number, optional): flatten up to this many levels, the default is 1
  • returns flatArray (array): a flattened array

Examples

@startDocuBlockInline aqlArrayFlatten_1 @EXAMPLE_AQL{aqlArrayFlatten_1} RETURN FLATTEN( [ 1, 2, [ 3, 4 ], 5, [ 6, 7 ], [ 8, [ 9, 10 ] ] ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayFlatten_1

To fully flatten the example array, use a depth of 2:

@startDocuBlockInline aqlArrayFlatten_2 @EXAMPLE_AQL{aqlArrayFlatten_2} RETURN FLATTEN( [ 1, 2, [ 3, 4 ], 5, [ 6, 7 ], [ 8, [ 9, 10 ] ] ], 2 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayFlatten_2

INTERSECTION()

INTERSECTION(array1, array2, ... arrayN) → newArray

Return the intersection of all arrays specified. The result is an array of values that occur in all arguments.

  • arrays (array, repeatable): an arbitrary number of arrays as multiple arguments (at least 2)
  • returns newArray (array): a single array with only the elements, which exist in all provided arrays. The element order is random. Duplicates are removed.

Examples

@startDocuBlockInline aqlArrayIntersection_1 @EXAMPLE_AQL{aqlArrayIntersection_1} RETURN INTERSECTION( [1,2,3,4,5], [2,3,4,5,6], [3,4,5,6,7] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayIntersection_1

@startDocuBlockInline aqlArrayIntersection_2 @EXAMPLE_AQL{aqlArrayIntersection_2} RETURN INTERSECTION( [2,4,6], [8,10,12], [14,16,18] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayIntersection_2

LAST()

LAST(anyArray) → lastElement

Get the last element of an array. It is the same as anyArray[-1].

  • anyArray (array): array with elements of arbitrary type
  • returns lastElement (any|null): the last element of anyArray or null if the array is empty.

Example

@startDocuBlockInline aqlArrayLast_1 @EXAMPLE_AQL{aqlArrayLast_1} RETURN LAST( [1,2,3,4,5] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayLast_1

LENGTH()

LENGTH(anyArray) → length

Determine the number of elements in an array.

  • anyArray (array): array with elements of arbitrary type
  • returns length (number): the number of array elements in anyArray.

LENGTH() can also determine the number of attribute keys of an object / document, the amount of documents in a collection and the character length of a string.

input length
String number of unicode characters
Number number of unicode characters that represent the number
Array number of elements
Object number of first level elements
true 1
false 0
null 0

Examples

@startDocuBlockInline aqlArrayLength_1 @EXAMPLE_AQL{aqlArrayLength_1} RETURN LENGTH( "🥑" ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayLength_1

@startDocuBlockInline aqlArrayLength_2 @EXAMPLE_AQL{aqlArrayLength_2} RETURN LENGTH( 1234 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayLength_2

@startDocuBlockInline aqlArrayLength_3 @EXAMPLE_AQL{aqlArrayLength_3} RETURN LENGTH( [1,2,3,4,5,6,7] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayLength_3

@startDocuBlockInline aqlArrayLength_4 @EXAMPLE_AQL{aqlArrayLength_4} RETURN LENGTH( [1,2,3,4,5,6,7] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayLength_4

@startDocuBlockInline aqlArrayLength_5 @EXAMPLE_AQL{aqlArrayLength_5} RETURN LENGTH( {a:1, b:2, c:3, d:4, e:{f:5,g:6}} ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayLength_5

MINUS()

MINUS(array1, array2, ... arrayN) → newArray

Return the difference of all arrays specified.

  • arrays (array, repeatable): an arbitrary number of arrays as multiple arguments (at least 2)
  • returns newArray (array): an array of values that occur in the first array, but not in any of the subsequent arrays. The order of the result array is undefined and should not be relied on. Duplicates will be removed.

Example

@startDocuBlockInline aqlArrayMinus_1 @EXAMPLE_AQL{aqlArrayMinus_1} RETURN MINUS( [1,2,3,4], [3,4,5,6], [5,6,7,8] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayMinus_1

NTH()

NTH(anyArray, position) → nthElement

Get the element of an array at a given position. It is the same as anyArray[position] for positive positions, but does not support negative positions.

  • anyArray (array): array with elements of arbitrary type
  • position (number): position of desired element in array, positions start at 0
  • returns nthElement (any|null): the array element at the given position. If position is negative or beyond the upper bound of the array, then null will be returned.

Examples

@startDocuBlockInline aqlArrayNth_1 @EXAMPLE_AQL{aqlArrayNth_1} RETURN NTH( [ "foo", "bar", "baz" ], 2 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayNth_1

@startDocuBlockInline aqlArrayNth_2 @EXAMPLE_AQL{aqlArrayNth_2} RETURN NTH( [ "foo", "bar", "baz" ], 3 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayNth_2

@startDocuBlockInline aqlArrayNth_3 @EXAMPLE_AQL{aqlArrayNth_3} RETURN NTH( [ "foo", "bar", "baz" ], -1 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayNth_3

OUTERSECTION()

OUTERSECTION(array1, array2, ... arrayN) → newArray

Return the values that occur only once across all arrays specified.

  • arrays (array, repeatable): an arbitrary number of arrays as multiple arguments (at least 2)
  • returns newArray (array): a single array with only the elements that exist only once across all provided arrays. The element order is random.

Example

@startDocuBlockInline aqlArrayOutersection_1 @EXAMPLE_AQL{aqlArrayOutersection_1} RETURN OUTERSECTION( [ 1, 2, 3 ], [ 2, 3, 4 ], [ 3, 4, 5 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayOutersection_1

POP()

POP(anyArray) → newArray

Remove the element at the end (right side) of array.

  • anyArray (array): an array with elements of arbitrary type
  • returns newArray (array): anyArray without the last element. If it's already empty or has only a single element left, an empty array is returned.

Examples

@startDocuBlockInline aqlArrayPop_1 @EXAMPLE_AQL{aqlArrayPop_1} RETURN POP( [ 1, 2, 3, 4 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayPop_1

@startDocuBlockInline aqlArrayPop_2 @EXAMPLE_AQL{aqlArrayPop_2} RETURN POP( [ 1 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayPop_2

POSITION()

POSITION(anyArray, search, returnIndex) → position

Return whether search is contained in array. Optionally return the position.

  • anyArray (array): the haystack, an array with elements of arbitrary type
  • search (any): the needle, an element of arbitrary type
  • returnIndex (bool, optional): if set to true, the position of the match is returned instead of a boolean. The default is false.
  • returns position (bool|number): true if search is contained in anyArray, false otherwise. If returnIndex is enabled, the position of the match is returned (positions start at 0), or -1 if it's not found.

To determine if or at which position a string occurs in another string, see the CONTAINS() string function.

Examples

@startDocuBlockInline aqlArrayPosition_1 @EXAMPLE_AQL{aqlArrayPosition_1} RETURN POSITION( [2,4,6,8], 4 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayPosition_1

@startDocuBlockInline aqlArrayPosition_2 @EXAMPLE_AQL{aqlArrayPosition_2} RETURN POSITION( [2,4,6,8], 4, true ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayPosition_2

PUSH()

PUSH(anyArray, value, unique) → newArray

Append value to the array specified by anyArray.

  • anyArray (array): array with elements of arbitrary type
  • value (any): an element of arbitrary type
  • unique (bool): if set to true, then value is not added if already present in the array. The default is false.
  • returns newArray (array): anyArray with value added at the end (right side)

Note: The unique flag only controls if value is added if it's already present in anyArray. Duplicate elements that already exist in anyArray will not be removed. To make an array unique, use the UNIQUE() function.

Examples

@startDocuBlockInline aqlArrayPush_1 @EXAMPLE_AQL{aqlArrayPush_1} RETURN PUSH([ 1, 2, 3 ], 4) @END_EXAMPLE_AQL @endDocuBlock aqlArrayPush_1

@startDocuBlockInline aqlArrayPush_2 @EXAMPLE_AQL{aqlArrayPush_2} RETURN PUSH([ 1, 2, 2, 3 ], 2, true) @END_EXAMPLE_AQL @endDocuBlock aqlArrayPush_2

REMOVE_NTH()

REMOVE_NTH(anyArray, position) → newArray

Remove the element at position from the anyArray.

  • anyArray (array): array with elements of arbitrary type
  • position (number): the position of the element to remove. Positions start at 0. Negative positions are supported, with -1 being the last array element. If position is out of bounds, the array is returned unmodified.
  • returns newArray (array): anyArray without the element at position

Examples

@startDocuBlockInline aqlArrayRemoveNth_1 @EXAMPLE_AQL{aqlArrayRemoveNth_1} RETURN REMOVE_NTH( [ "a", "b", "c", "d", "e" ], 1 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayRemoveNth_1

@startDocuBlockInline aqlArrayRemoveNth_2 @EXAMPLE_AQL{aqlArrayRemoveNth_2} RETURN REMOVE_NTH( [ "a", "b", "c", "d", "e" ], -2 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayRemoveNth_2

REMOVE_VALUE()

REMOVE_VALUE(anyArray, value, limit) → newArray

Remove all occurrences of value in anyArray. Optionally with a limit to the number of removals.

  • anyArray (array): array with elements of arbitrary type
  • value (any): an element of arbitrary type
  • limit (number, optional): cap the number of removals to this value
  • returns newArray (array): anyArray with value removed

Examples

@startDocuBlockInline aqlArrayRemoveValue_1 @EXAMPLE_AQL{aqlArrayRemoveValue_1} RETURN REMOVE_VALUE( [ "a", "b", "b", "a", "c" ], "a" ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayRemoveValue_1

@startDocuBlockInline aqlArrayRemoveValue_2 @EXAMPLE_AQL{aqlArrayRemoveValue_2} RETURN REMOVE_VALUE( [ "a", "b", "b", "a", "c" ], "a", 1 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayRemoveValue_2

REMOVE_VALUES()

REMOVE_VALUES(anyArray, values) → newArray

Remove all occurrences of any of the values from anyArray.

  • anyArray (array): array with elements of arbitrary type
  • values (array): an array with elements of arbitrary type, that shall be removed from anyArray
  • returns newArray (array): anyArray with all individual values removed

Example

@startDocuBlockInline aqlArrayRemoveValues_1 @EXAMPLE_AQL{aqlArrayRemoveValues_1} RETURN REMOVE_VALUES( [ "a", "a", "b", "c", "d", "e", "f" ], [ "a", "f", "d" ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayRemoveValues_1

REVERSE()

REVERSE(anyArray) → reversedArray

Return an array with its elements reversed.

  • anyArray (array): array with elements of arbitrary type
  • returns reversedArray (array): a new array with all elements of anyArray in reversed order

Example

@startDocuBlockInline aqlArrayReverse_1 @EXAMPLE_AQL{aqlArrayReverse_1} RETURN REVERSE ( [2,4,6,8,10] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayReverse_1

SHIFT()

SHIFT(anyArray) → newArray

Remove the element at the start (left side) of anyArray.

  • anyArray (array): array with elements with arbitrary type
  • returns newArray (array): anyArray without the left-most element. If anyArray is already empty or has only one element left, an empty array is returned.

Examples

@startDocuBlockInline aqlArrayShift_1 @EXAMPLE_AQL{aqlArrayShift_1} RETURN SHIFT( [ 1, 2, 3, 4 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayShift_1

@startDocuBlockInline aqlArrayShift_2 @EXAMPLE_AQL{aqlArrayShift_2} RETURN SHIFT( [ 1 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayShift_2

SLICE()

SLICE(anyArray, start, length) → newArray

Extract a slice of anyArray.

  • anyArray (array): array with elements of arbitrary type
  • start (number): start extraction at this element. Positions start at 0. Negative values indicate positions from the end of the array.
  • length (number, optional): extract up to length elements, or all elements from start up to length if negative (exclusive)
  • returns newArray (array): the specified slice of anyArray. If length is not specified, all array elements starting at start will be returned.

Examples

@startDocuBlockInline aqlArraySlice_1 @EXAMPLE_AQL{aqlArraySlice_1} RETURN SLICE( [ 1, 2, 3, 4, 5 ], 0, 1 ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySlice_1

@startDocuBlockInline aqlArraySlice_2 @EXAMPLE_AQL{aqlArraySlice_2} RETURN SLICE( [ 1, 2, 3, 4, 5 ], 1, 2 ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySlice_2

@startDocuBlockInline aqlArraySlice_3 @EXAMPLE_AQL{aqlArraySlice_3} RETURN SLICE( [ 1, 2, 3, 4, 5 ], 3 ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySlice_3

@startDocuBlockInline aqlArraySlice_4 @EXAMPLE_AQL{aqlArraySlice_4} RETURN SLICE( [ 1, 2, 3, 4, 5 ], 1, -1 ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySlice_4

@startDocuBlockInline aqlArraySlice_5 @EXAMPLE_AQL{aqlArraySlice_5} RETURN SLICE( [ 1, 2, 3, 4, 5 ], 0, -2 ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySlice_5

@startDocuBlockInline aqlArraySlice_6 @EXAMPLE_AQL{aqlArraySlice_6} RETURN SLICE( [ 1, 2, 3, 4, 5 ], -3, 2 ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySlice_6

SORTED()

SORTED(anyArray) → newArray

Sort all elements in anyArray. The function will use the default comparison order for AQL value types.

  • anyArray (array): array with elements of arbitrary type
  • returns newArray (array): anyArray, with elements sorted

Example

@startDocuBlockInline aqlArraySorted_1 @EXAMPLE_AQL{aqlArraySorted_1} RETURN SORTED( [ 8,4,2,10,6 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySorted_1

SORTED_UNIQUE()

SORTED_UNIQUE(anyArray) → newArray

Sort all elements in anyArray. The function will use the default comparison order for AQL value types. Additionally, the values in the result array will be made unique.

  • anyArray (array): array with elements of arbitrary type
  • returns newArray (array): anyArray, with elements sorted and duplicates removed

Example

@startDocuBlockInline aqlArraySortedUnique_1 @EXAMPLE_AQL{aqlArraySortedUnique_1} RETURN SORTED_UNIQUE( [ 8,4,2,10,6,2,8,6,4 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArraySortedUnique_1

UNION()

UNION(array1, array2, ... arrayN) → newArray

Return the union of all arrays specified.

  • arrays (array, repeatable): an arbitrary number of arrays as multiple arguments (at least 2)
  • returns newArray (array): all array elements combined in a single array, in any order

Examples

@startDocuBlockInline aqlArrayUnion_1 @EXAMPLE_AQL{aqlArrayUnion_1} RETURN UNION( [ 1, 2, 3 ], [ 1, 2 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayUnion_1

Note: No duplicates will be removed. In order to remove duplicates, please use either UNION_DISTINCT() or apply UNIQUE() on the result of UNION():

@startDocuBlockInline aqlArrayUnion_2 @EXAMPLE_AQL{aqlArrayUnion_2} RETURN UNIQUE( UNION( [ 1, 2, 3 ], [ 1, 2 ] ) ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayUnion_2

UNION_DISTINCT()

UNION_DISTINCT(array1, array2, ... arrayN) → newArray

Return the union of distinct values of all arrays specified.

  • arrays (array, repeatable): an arbitrary number of arrays as multiple arguments (at least 2)
  • returns newArray (array): the elements of all given arrays in a single array, without duplicates, in any order

Example

@startDocuBlockInline aqlArrayUnionDistinct_1 @EXAMPLE_AQL{aqlArrayUnionDistinct_1} RETURN UNION_DISTINCT( [ 1, 2, 3 ], [ 1, 2 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayUnionDistinct_1

UNIQUE()

UNIQUE(anyArray) → newArray

Return all unique elements in anyArray. To determine uniqueness, the function will use the comparison order.

  • anyArray (array): array with elements of arbitrary type
  • returns newArray (array): anyArray without duplicates, in any order

Example

@startDocuBlockInline aqlArrayUnique_1 @EXAMPLE_AQL{aqlArrayUnique_1} RETURN UNIQUE( [ 1,2,2,3,3,3,4,4,4,4,5,5,5,5,5 ] ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayUnique_1

UNSHIFT()

UNSHIFT(anyArray, value, unique) → newArray

Prepend value to anyArray.

  • anyArray (array): array with elements of arbitrary type
  • value (any): an element of arbitrary type
  • unique (bool): if set to true, then value is not added if already present in the array. The default is false.
  • returns newArray (array): anyArray with value added at the start (left side)

Note: The unique flag only controls if value is added if it's already present in anyArray. Duplicate elements that already exist in anyArray will not be removed. To make an array unique, use the UNIQUE() function.

Examples

@startDocuBlockInline aqlArrayUnshift_1 @EXAMPLE_AQL{aqlArrayUnshift_1} RETURN UNSHIFT( [ 1, 2, 3 ], 4 ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayUnshift_1

@startDocuBlockInline aqlArrayUnshift_2 @EXAMPLE_AQL{aqlArrayUnshift_2} RETURN UNSHIFT( [ 1, 2, 3 ], 2, true ) @END_EXAMPLE_AQL @endDocuBlock aqlArrayUnshift_2