Syntax and examples of built-in data processing functions - CloudFlow

CloudFlow's Flow Definition Language (FDL) provides built-in functions for data processing within workflow definitions. Use these functions to manipulate strings, arrays, maps, and JSON data without writing external function code.

Important

To use a built-in function in an input or output constructor, append .$ to the constructor key. This tells CloudFlow to evaluate the value as an expression. Without the .$ suffix, the value is treated as a plain string. A maximum of 10 nested function calls are supported per expression.

Example: Using a built-in function in an FDL constructor

{
  "inputMappings": {
    "greeting.$": "format('Hello, {}', $input.username)"
  }
}

In this example, greeting.$ tells CloudFlow that the value is an expression containing the format function, not a literal string.

Function reference

The following tables list all built-in functions, grouped by category.

Common operations

Function	Purpose
`format`	Format a string using `{}` placeholders
`length`	Get the length of a string, array, or map
`regexMatchString`	Match a string against a regular expression
`split`	Split a string by a delimiter

Array operations

Function	Purpose
`arrayContains`	Check whether an array contains a specific element
`arrayUnique`	Remove duplicate elements from an array
`toArray`	Convert a variable number of arguments into an array

Map operations

Function	Purpose
`mapKeys`	Extract all keys from a JSON object or map as an array
`mapValues`	Extract all values from a JSON object or map as an array
`mapValuesPartition`	Extract values from a map and split them into sub-arrays by step size

Data encoding and decoding

Function	Purpose
`toBase64`	Encode a string to Base64
`fromBase64`	Decode a Base64-encoded string

Hash calculation and UUID generation

Function	Purpose
`hash`	Generate a hash value using a specified algorithm
`uuid`	Generate a universally unique identifier (UUID)

JSON data operations

Function	Purpose
`jsonToString`	Convert a JSON object or map to a JSON string
`stringToJson`	Parse a JSON string into a JSON object or map
`jsonMerge`	Merge two JSON objects or maps into one

Common operations

`format`

Formats a string by replacing {} placeholders with the provided arguments, in order.

Syntax

format(template, arg1, arg2, ...)

Parameters

Parameter	Type	Required	Description
template	`string`	Yes	A template string containing `{}` placeholders
arg1, arg2, ...	`any`	Yes	Values to substitute into the placeholders, in order

Return type: string

Examples

format("hello {}", "world")
// Returns: "hello world"

FDL usage:

{
  "message.$": "format('Task {} completed at {}', $input.taskName, $input.timestamp)"
}

`length`

Returns the length of a string, array, or map.

For a string, returns the number of characters.
For an array, returns the number of elements.
For a map, returns the number of key-value pairs.

Syntax

length(value)

Parameters

Parameter	Type	Required	Description
value	`string`, `[]any`, or `map[string]any`	Yes	The string, array, or map to measure

Return type: int

Examples

length([1, 2, 3])
// Returns: 3

length({"name": "Tom", "age": 10})
// Returns: 2

length("name")
// Returns: 4

FDL usage:

{
  "itemCount.$": "length($input.orderItems)"
}

`regexMatchString`

Tests whether a string matches a regular expression pattern. Returns true if the pattern matches, false otherwise.

Syntax

regexMatchString(pattern, value)

Parameters

Parameter	Type	Required	Description
pattern	`string`	Yes	The regular expression pattern
value	`string`	Yes	The string to test against the pattern

Return type: bool

Examples

regexMatchString("p([a-z]+)ch", "peach")
// Returns: true

regexMatchString("p([a-z]+)ch", "p123ch")
// Returns: false

FDL usage:

{
  "isValid.$": "regexMatchString('^[a-zA-Z0-9]+$', $input.userId)"
}

`split`

Splits a string into an array of substrings based on a delimiter.

Syntax

split(value, delimiter)

Parameters

Parameter	Type	Required	Description
value	`string`	Yes	The string to split
delimiter	`string`	Yes	The delimiter to split on

Return type: []string

Examples

split("item1,item2,item3", ",")
// Returns: ["item1", "item2", "item3"]

FDL usage:

{
  "tags.$": "split($input.tagString, ',')"
}

Array operations

`arrayContains`

Checks whether an array contains a specific element. Returns true if the element is found, false otherwise.

Syntax

arrayContains(array, element)

Parameters

Parameter	Type	Required	Description
array	`[]any`	Yes	The array to search
element	`any`	Yes	The element to search for

Return type: bool

Examples

arrayContains(["Tom", 10], 10)
// Returns: true

arrayContains(["Tom", 10], "Jack")
// Returns: false

FDL usage:

{
  "isAllowed.$": "arrayContains($input.allowedRegions, $input.targetRegion)"
}

`arrayUnique`

Removes duplicate elements from an array and returns the deduplicated result.

Syntax

arrayUnique(array)

Parameters

Parameter	Type	Required	Description
array	`[]any`	Yes	The array to deduplicate

Return type: []any

Examples

arrayUnique([1, 2, 3, 1])
// Returns: [1, 2, 3]

`toArray`

Converts a variable number of arguments into a single array.

Syntax

toArray(arg1, arg2, ...)

Parameters

Parameter	Type	Required	Description
arg1, arg2, ...	`any`	Yes	One or more values to combine into an array

Return type: []any

Examples

toArray(1,'strig',$Input.var)
// Returns: []any{1, 'string', $valueOfVar}

Map operations

`mapKeys`

Extracts all keys from a JSON object or map and returns them as a string array.

Syntax

mapKeys(map)

Parameters

Parameter	Type	Required	Description
map	`map[string]any`	Yes	The JSON object or map to extract keys from

Return type: []string

Examples

mapKeys({"name": "Tom", "age": 10})
// Returns: ["name", "age"]

`mapValues`

Extracts all values from a JSON object or map and returns them as an array.

Syntax

mapValues(map)

Parameters

Parameter	Type	Required	Description
map	`map[string]any`	Yes	The JSON object or map to extract values from

Return type: []any

Examples

mapValues({"name": "Tom", "age": 10})
// Returns: ["Tom", 10]

`mapValuesPartition`

Extracts all values from a JSON object or map and partitions them into sub-arrays of a specified size.

Syntax

mapValuesPartition(map, stepSize)

Parameters

Parameter	Type	Required	Description
map	`map[string]any`	Yes	The JSON object or map to extract values from
stepSize	`int`	Yes	The number of elements per sub-array

Return type: [][]any

Examples

mapValuesPartition({"name": "Tom", "age": 10}, 1)
// Returns: ["Tom"],[10]

Data encoding and decoding

`toBase64`

Encodes a string to Base64.

Syntax

toBase64(value)

Parameters

Parameter	Type	Required	Description
value	`string`	Yes	The string to encode

Return type: string

Examples

toBase64("FnF")
// Returns: "Rm5G"

`fromBase64`

Decodes a Base64-encoded string back to its original value.

Syntax

fromBase64(value)
ParametersParameterTypeRequiredDescriptionvaluestringYesThe Base64-encoded string to decode
Return type: string
ExamplesfromBase64("Rm5G")
// Returns: "FnF"

Hash calculation and UUID generation

`hash`

Generates a hash value for the given input using a specified algorithm.

Syntax

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Parameters

Parameter	Type	Required	Description
input	`string`	Yes	The string to hash
algorithm	`string`	Yes	The hash algorithm. Supported values: `MD5`, `SHA-1`, `SHA-256`, `SHA-512`

Return type: string

Examples

hash("abc", "MD5")
// Returns: "900150983cd24fb0d6963f7d28e17f72"

FDL usage:

{
  "checksum.$": "hash($input.payload, 'SHA-256')"
}

`uuid`

Generates a universally unique identifier (UUID).

Syntaxuuid()

Parameters

None.

Return type: string

Examples

uuid() // Returns: "159fd8c1-2ec3-4d7b-b9fd-60b9d8841000"
FDL uid="dfc2079465bd1_22"e-type="xCode" data-tag="codeblock" id="dfc2079465bd1" outputclass="language-json">{ "requestId.$": "uuid()" }

JSON data operations

`jsonToString`

Converts a JSON object or map to its string representation.

Syid="dfc2079465bd1_23"code-type="xCode" data-tag="codeblock" id="dfc2079465bd1" outputclass="language-bash">jsonToString(value)

Parameters

Parameter	Type	Required	Description
value	`map[string]any`	Yes	The JSON object or map to serialize

Return type: string

Examples

toJSON({"name": "Tom", "age": 10}) // Returns: '{"name": "Tom", "age": 10}'

`stringToJson`

Parses a JSON string into a JSON object or map.

Syntax

stringToJson(value)

Parameters

Parameter	Type	Required	Description
value	`string`	Yes	A valid JSON string

Return type: map[string]any

Examples

stringToJson('{"name": "Tom", "age": 10}')
// Returns: {"name": "Tom", "age": 10}

FDL usage:

{
  "parsedBody.$": "stringToJson($input.responseBody)"
}

`jsonMerge`

Merges two JSON objects or maps into one.

jsonMerge(object1, object2)
ParametersParameterTypeRequiredDescriptionobject1map[string]anyYesThe first JSON object or mapobject2map[string]anyYesThe second JSON object or map
Return type: map[string]any
ExamplesjsonMerge({"name": "Tom", "age": 10}, {"name": "Tom", "address": "beijing"})
// Returns: {"name": "Tom", "age": 10, "address": "beijing"}
{
  "mergedConfig.$": "jsonMerge($input.defaultConfig, $input.userOverrides)"
}