Standard library overview

The Workflows standard library includes modules and frequently used functions, such as for data type and format conversions. There is no need to import or load libraries in a workflow—library functions work out of the box.

All functions can be called using call steps, but only non-blocking functions can be used inside an expression. For example, HTTP calls, sys.sleep, and sys.log cannot be used inside an expression. For more information, see Blocking calls.

Data type functions

The following conversion functions are supported:

double(): Accepts an attribute of type string or integer and returns a double.
int(): Accepts an attribute of type string or double and returns an integer.
string(): Accepts an attribute of type integer, double, or boolean and returns a string.

The following functions operate on lists, maps, and strings:

in(): Checks whether a given key is present in a map. See Check existence of a key in a map.
keys(): Accepts an attribute of type map and returns a list of key elements in the map.
len(): Computes the length of value according to its type. Accepts an attribute of type string, list, or map and returns an integer.
- string: Returns the number of characters in the string.
- list: Returns the number of elements in the list.
- map: Returns the number of key-value entries stored in the map.

Random number generation

You can use sys.now to generate multiple random numbers. (The function returns a floating point number with nanosecond precision.) If you need only one number, use sys.get_env to retrieve the workflow's execution identifier. If a unique ID is needed, you can use string() to convert the number returned from sys.now to a string and combine it with the execution ID; for example, some_execution_id1635892223.4459958. Optionally, you can use a Cloud Function to generate a number and call the Cloud Function from your workflow.

Module: base64

Base64 encoding/decoding.

Functions
`decode`	Decodes given Base64-encoded string to bytes.
`encode`	Encodes given bytes to Base64 text.

Module: errors

Constructors for commonly used exceptions.

Functions
`index_error`	Returns a dictionary object with an `IndexError` tag.
`key_error`	Returns a dictionary object with a `KeyError` tag.
`not_implemented_error`	Returns a dictionary object with a `NotImplementedError` tag.
`recursion_error`	Returns a dictionary object with a `RecursionError` tag.
`resource_limit_error`	Returns a dictionary object with a `ResourceLimitError` tag.
`system_error`	Returns a dictionary object with a `SystemError` tag.
`timeout_error`	Returns a dictionary object with a `TimeoutError` tag.
`type_error`	Returns a dictionary object with a `TypeError` tag.
`value_error`	Returns a dictionary object with a `ValueError` tag.
`zero_division_error`	Returns a dictionary object with a `ZeroDivisionError` tag.

Module: events

Events support.

Functions
`await_callback`	Waits for a callback to be received at the given endpoint.
`create_callback_endpoint`	Creates a callback endpoint expecting the specified HTTP method.

Module: experimental.executions

Execution management.

Functions
`execution_error`	Raised when a Workflow Execution finishes with an error or gets cancelled.
`map`	Starts workflow executions and waits for all of them to finish.
`run`	Starts a workflow execution and waits for it to finish.

Module: http

HTTP/S request support.

Functions
`auth_error`	Returns a map object with an `AuthError` tag.
`connection_error`	Raised when an HTTP request fails due to a connection error.
`default_retry_predicate`	Simple default retry predicate for idempotent targets.
`default_retry_predicate_non_idempotent`	Simple default retry predicate for non-idempotent targets.
`delete`	Sends an HTTP DELETE request to the specified URL.
`get`	Sends an HTTP GET request to the specified URL.
`http_error`	Raised when an HTTP request fails with an HTTP error status.
`patch`	Sends an HTTP PATCH request to the specified URL.
`post`	Sends an HTTP POST request to the specified URL.
`put`	Sends an HTTP PUT request to the specified URL.
`request`	Sends an HTTP request.

Objects
`default_retry`	Simple default retry policy for idempotent targets.
`default_retry_non_idempotent`	Simple default retry policy for non-idempotent targets.

Module: json

JSON encoding/decoding.

Functions
`decode`	Decodes given JSON bytes (assuming UTF-8), or a string, into an object.
`encode`	Encodes given input object to JSON bytes, using UTF-8 charset.
`encode_to_string`	Encodes given object to a JSON string.

Module: list

List utility.

Functions
`concat`	Creates a copy of a list with a new element concatenated at the end.

Module: retry

Support for retries.

Functions
`always`	Convenience retry condition that retries on any error.
`never`	Convenience retry condition that retries on no error at all.

Objects
`default_backoff`	Simple default truncated exponential backoff policy.

Module: sys

Common system interface, with platform-dependent implementation.

Functions
`get_env`	Retrieves the value of the specified environment variable.
`log`	Writes one of `data`, `text`, or `json` to the log at specified severity.
`now`	Returns wall time, as a floating-point number of seconds since Epoch.
`sleep`	Suspends execution for the given number of seconds.
`sleep_until`	Suspends execution until the given time.

Module: text

Text processing.

To concatenate a string, see Strings.

Functions
`decode`	Decodes given data to string, assuming the specified character set.
`encode`	Encodes given text to bytes, using the specified character set.
`find_all`	Finds the index of all instances of a substring in a string.
`find_all_regex`	Finds all matches of a regular expression in a string.
`match_regex`	Reports whether a string contains a match of a regular expression.
`replace_all`	Replaces all instances of a substring with a new string.
`replace_all_regex`	Replaces all matches of a regular expression with a new string.
`split`	Splits the source string into a list of all substrings between each instance of the separator.
`substring`	Extracts the substring between two indexes of a source string.
`to_lower`	Returns a string with all Unicode letters mapped to their lowercase.
`to_upper`	Returns a string with all Unicode letters mapped to their uppercase.

Module: time

Time-related utility functions.

Functions
`format`	Formats the given timestamp as a human-readable string.
`parse`	Parses given ISO 8601-compatible string into a timestamp.

Module: urlencode

Encodes given input to a url-encoded string.

Functions
`encode`	Encodes given input object to a string, using UTF-8 charset.