Power Automate (WDL) function
concat — Power Automate (WDL) function reference
Join strings together.
Syntax
wdl
concat(text1, text2, ...)
Examples
wdl
concat('PO-', variables('id'))→ "PO-1042"
wdl
concat('Order #', string(triggerBody()?['orderId']), ' — ', triggerBody()?['status'])→ "Order #1042 — Shipped"
A common pattern for building a unique, sortable file name.
wdl
concat(formatDateTime(utcNow(), 'yyyyMMdd'), '_', triggerBody()?['fileName'])
→ "20260707_invoice.pdf"
Common mistakes & gotchas
- concat() only accepts strings. Pass a number or boolean straight in and the flow throws an 'InvalidTemplate' error at runtime — wrap non-string arguments in string() first.
- concat() does not insert a separator between arguments automatically. To join an array with a delimiter, use join(), not concat().
Related Workflow Definition Language functions
From Strings
Used in these tutorials
Beyond Built-in Charts: Using QuickChart for Custom Visuals in Power AppsFrom Breaking to Resilient: Three Error-Handling Strategies in Power AutomateMastering Table Variables in Copilot Studio: Add, Remove, and Clear via YAMLFrom Raw Strings to Structured Data: A Guide to Power Automate Text Functions