Workato Expression Language ​

WEL (Workato Expression Language) is Workato's transformation language. It reshapes data as it moves between systems, renaming and restructuring fields, joining and aggregating records, converting types, and formatting values for the destination.

WEL is part of the Workato platform, so there's nothing to install, nothing to connect to, and no runtime to manage. WEL runs on Workato's data plane alongside your recipes.

Why WEL exists ​

Integration is a translation problem. Systems agree on what an object is and disagree on its format. For example:

• The source sends a full name and the destination expects two fields.
• The source sends "12.50" as a string and the destination expects an exact decimal.
• The source sends a UTC timestamp and the destination expects a local calendar date.

Translating well requires more than field mapping. Using a general-purpose scripting language for translations presents problems, such as a runtime to secure, dependencies to keep current, and code that only its author can safely change.

WEL is built and scoped for transformations, so you can integrate systems without encountering the security and maintenance issues of a general-purpose language.

What makes WEL a language ​

Four properties make WEL a language rather than a mapping tool, and each prevents a class of bug that field mapping cannot:

• 16 data types: Exact decimals and zone-aware temporal types keep business data from quietly changing shape in transit.

• 245 built-in functions: They span strings, lists, maps, temporal arithmetic, numeric rounding, encoding, escaping, Unicode, and cryptography, all in the language rather than in a library you add.

• Composition: The pipeline operator >> lets a multi-step transformation read in the order it happens rather than inside-out:

  text

  _.orders
    >> filter_by(o ~> o.status == 'open')
    >> sort_by(o ~> o.total)
    >> reverse
    >> take(3)

• Strictness: By default, WEL doesn't coerce a value to make an expression succeed and a List or Map never becomes a string by accident. WEL raises a numbered error for mismatches instead of producing a plausible wrong answer.

Use cases ​

Use WEL when the transformation is more than a field mapping:

• Reshape a nested API response into the flat record a destination expects.
• Group, deduplicate, or aggregate a batch of records.
• Calculate money, where the difference between exact and approximate arithmetic reaches an invoice.
• Normalize dates, time zones, and text arriving from systems that disagree.
• Build a formatted string safely, such as a CSV row, a query, a URL, or a message body.
• Validate a payload and route what fails, instead of passing bad data on.

You don't need WEL for a straight one-to-one field mapping.

Where WEL runs ​

WEL runs on Workato's data plane. The data plane is the part of the platform that processes your data while a recipe runs, as opposed to the control plane, which handles configuration. WEL runs in the same place as the rest of your recipe, so your data doesn't move to reach it.

WEL is available in recipes through the Transform data action. You declare input shape, write an expression, and declare the output shape. The results become datapills for downstream steps.

Next steps ​

• Quickstart: An example showing different WEL workflows.
• Transform data: Use WEL in recipes through a connector.
• Data types: The 16 WEL data types and when to use each one.
• Standard library: All 245 WEL functions.
• Cookbook: Examples of common integration problems.
• Error codes: Troubleshoot job failures.