Array Operators - DataLogic-rs

map

The map operator transforms each item in an array or object using a specified expression. It applies a transformation function to each element of an array or each value of an object and returns a new array/object containing the results.

Syntax

{ "map": [source, transformation_expression] }

Parameters

Parameter	Description
source	The array or object to transform
transformation_expression	The expression to apply to each element. Use `{"val": []}` to access the current element, `{"val": "_key"}` for object keys.

Example: Double each number

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Example: Extract property from objects

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Example: Map over object properties

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some

The some operator checks if at least one element in an array satisfies a condition.

Syntax

{ "some": [array, condition] }

Parameters

Parameter	Description
array	The array to check
condition	The condition to test each element against

Example: Check if any item has a quantity of 10 or more

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all

The all operator checks if all elements in an array satisfy a condition.

Syntax

{ "all": [array, condition] }

Parameters

Parameter	Description
array	The array to check
condition	The condition to test each element against

Example: Check if all users are adults

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none

The none operator checks if no elements in an array satisfy a condition. It's effectively the opposite of the some operator.

Syntax

{ "none": [array, condition] }

Parameters

Parameter	Description
array	The array to check
condition	The condition to evaluate for each element

Example: Check if none of the values are negative

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Example: Check if none of the items are in stock

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filter

The filter operator creates a new array with all elements that pass a condition.

Syntax

{ "filter": [array, condition] }

Parameters

Parameter	Description
array	The array to filter
condition	The condition each element must satisfy

Example: Filter out even numbers

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Example: Filter for adult users

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Example: Filter Products by Price and Availability

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reduce

The reduce operator applies a function to each element in the array to reduce it to a single value.

Syntax

{ "reduce": [array, accumulator_function, initial_value] }

Parameters

Parameter	Description
array	The array to reduce
accumulator_function	The function to apply to each element and the accumulator
initial_value	The initial value of the accumulator

Example: Sum of numbers

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Example: Calculating total order value

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merge

The merge operator combines multiple arrays into a single array.

Syntax

{ "merge": [array1, array2, ...] }

Parameters

Parameter	Description
array1, array2, ...	Arrays to merge together

Example: Merge multiple arrays

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Example: Merge and flatten nested arrays

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in

The in operator checks if a specific value exists in an array.

Syntax

{ "in": [value, array] }

Parameters

Parameter	Description
value	The value to search for
array	The array to search in

Example: Check if a value is in an array

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Example: Check for permissions

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length

The length operator returns the number of elements in an array or the number of characters in a string.

Syntax

{ "length": value }

Parameters

Parameter	Description
value	The array or string to get the length of

Example: Get array length

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Example: Get string length

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Notes

For strings, returns the number of characters (Unicode code points), not bytes.
Will throw an error if the value is not an array or string.

slice

The slice operator extracts a portion of an array or string based on start, end, and step parameters.

Syntax

{ "slice": [collection, start, end, step] }

Parameters

Parameter	Description	Required
collection	The array or string to slice	Yes
start	The starting index (inclusive). Negative indices count from the end.	No (defaults to 0)
end	The ending index (exclusive). Negative indices count from the end.	No (defaults to length)
step	The step value. Negative values iterate in reverse.	No (defaults to 1)

Example: Basic array slicing

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Example: Negative indices

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Example: With step value

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Example: String slicing

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Example: Reverse a string with negative step

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Notes

Negative indices count from the end of the array or string (-1 is the last element).
Specifying null for end uses the collection's length by default.
Using a negative step iterates through the collection in reverse order.
If a step of 0 is given, an error will be thrown.

sort

The sort operator sorts an array in ascending or descending order, with optional field extraction for sorting objects.

Syntax

{ "sort": [array, direction, field_extractor] }

Parameters

Parameter	Description	Required
array	The array to sort	Yes
direction	Boolean or string indicating sort direction: true/false, "asc"/"desc"	No (defaults to true/ascending)
field_extractor	Expression to extract sort values from objects	No

Example: Basic sorting

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Example: Descending order

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Example: Sort by field

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Example: Sort by complex expression

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Notes

When sorting mixed data types, the following order is used: null < boolean < number < string < array < object.
For direction, both boolean values (true/false) and strings ("asc"/"desc") are supported.
The field_extractor is evaluated for each array element to determine its sort key.
Complex sort expressions can be used to sort by calculated values.
Sorts are stable, meaning equal elements maintain their original order.

Array Operators Overview

DataLogic-rs provides powerful array operators that help you work with arrays:

map - Transform each element in an array
filter - Remove elements that don't match a condition
reduce - Combine array elements into a single value
all - Check if all elements match a condition
some - Check if at least one element matches a condition
none - Check if no elements match a condition
merge - Combine multiple arrays into one
in - Check if a value exists in an array

These operators can be combined to perform complex array operations efficiently.