String Functions in Power Automate

🔧 String Functions in Power Automate

String functions in Power Automate provide powerful tools for manipulating text values. Whether you’re combining text, extracting parts of a string, or transforming input data, these functions help you streamline complex flows and clean data dynamically.

Mastering string functions in Power Automate is essential for building reliable flows that work with user input, emails, file paths, and external data sources like SharePoint, Dataverse, or HTTP APIs.

📊 Common String Functions in Power Automate

The table below highlights the most widely used string functions in Power Automate. Each function includes a purpose, syntax, and a real-world example.

Function	Purpose	Syntax	Example	Output
`concat()`	Joins two or more strings	`concat(string1, string2)`	`concat('Hello ', 'World')`	`Hello World`
`substring()`	Extracts a portion of a string	`substring(string, startIndex, length)`	`substring('PowerAutomate', 0, 5)`	`Power`
`replace()`	Replaces one substring with another	`replace(text, old, new)`	`replace('abc123', '123', 'XYZ')`	`abcXYZ`
`toLower()`	Converts text to lowercase	`toLower('ABC')`	`abc`	`abc`
`toUpper()`	Converts text to uppercase	`toUpper('power')`	`POWER`	`POWER`
`trim()`	Removes leading and trailing whitespace	`trim(string)`	`trim(' hello ')`	`hello`
`length()`	Returns the length of a string	`length('Power')`	`5`	`5`
`split()`	Splits a string into an array by a delimiter	`split(string, delimiter)`	`split('a,b,c', ',')`	`['a','b','c']`
`indexOf()`	Returns the position of a substring	`indexOf('abcde', 'c')`	`2`	`2`
`lastIndexOf()`	Finds last occurrence of a substring	`lastIndexOf('abcabc', 'a')`	`3`	`3`

💡 Advanced String Functions for Power Users

For more complex flows, Power Automate offers advanced string functions:

Function	Purpose	Example	Output
`startsWith()`	Checks if string starts with a value	`startsWith('PowerAutomate', 'Power')`	`true`
`endsWith()`	Checks if string ends with a value	`endsWith('report.pdf', '.pdf')`	`true`
`contains()`	Checks if string contains a value	`contains('hello world', 'world')`	`true`
`equals()`	Compares two strings (case-sensitive)	`equals('abc', 'ABC')`	`false`
`guid()`	Generates a unique identifier	`guid()`	`e.g., 4e7b9d...`

🛠️ Practical Examples Using String Functions

1. Format a File Name with Current Date

concat('Invoice_', formatDateTime(utcNow(), 'yyyyMMdd'), '.pdf')

Output: Invoice_20250807.pdf

2. Clean and Capitalize User Input

toUpper(trim(replace(triggerBody()?['comment'], '\n', ' ')))

Use Case: Clean up form comments before sending in an email.

3. Extract Domain from Email Address

split(triggerBody()?['email'], '@')[1]

Output (from ‘user@company.com‘): company.com

✅ Best Practices for Using String Functions in Power Automate

Use trim() to clean user input before further processing.
Combine split() and indexOf() cautiously when extracting substrings.
Use coalesce() to prevent errors when strings may be null or empty.
Avoid hardcoding indexes unless the format is guaranteed.
Break down complex expressions into multiple Compose actions for readability.

🚫 Common Mistakes and How to Avoid Them

Mistake	Issue	Fix
Hardcoded substring indexes	Can break if input varies	Use `indexOf()` or `split()` instead
Null reference errors	Missing or empty values	Use `coalesce(value, 'default')`
Wrong delimiter in `split()`	Unexpected array result	Inspect actual input data before splitting
Nested functions too complex	Hard to read & debug	Use multiple Compose steps and name them clearly

Would you like a downloadable function reference sheet or should I continue with the next section, such as “Date and Time Manipulation in Power Automate”?

Curriculum

String Functions in Power Automate