Collection and Array Functions in Power Automate

📦 Collection and Array Functions in Power Automate

Collection and array functions in Power Automate are essential when dealing with multiple values such as lists, tables, or JSON arrays. Whether you’re looping through a set of emails, filtering SharePoint items, or parsing data from an API, these functions help you manipulate and control grouped data with precision.

Mastering collection and array functions in Power Automate allows you to efficiently access, filter, transform, and restructure data in your flows.

📚 Why Use Collection and Array Functions in Power Automate?

You’ll need collection and array functions in Power Automate when:

Looping through dynamic content (like rows or items)
Filtering or selecting specific elements from an array
Joining arrays or breaking them apart
Sorting data for reporting or analysis
Removing duplicates or transforming structures

These functions are critical when you’re using actions like “Apply to each”, “Select”, “Filter array”, or parsing JSON.

💼 Real-World Use Cases

Use Case	Description
Filter SharePoint items where status = ‘Open’	Use `filter()` function
Join list of emails into one string	Use `join()`
Find the highest-scoring record	Use `max()` on array of numbers
Get all items assigned to a user	Use `where()` or `filter()`
Remove duplicates from collection	Use `union()` or custom expression

🔧 Common Collection and Array Functions in Power Automate

Here’s a table of frequently used collection and array functions in Power Automate:

Function	Purpose	Syntax	Example	Output
`createArray()`	Creates a new array	`createArray(1, 2, 3)`	`[1,2,3]`	Array
`length()`	Returns number of items	`length(body('Get_Items'))`	`5`	Count
`join()`	Combines array items into string	`join(['A','B','C'], ',')`	`A,B,C`	Text
`union()`	Merges two arrays, removes duplicates	`union(array1, array2)`	Merged unique
`intersection()`	Common items from arrays	`intersection(array1, array2)`	Matching values
`skip()`	Skips first N items	`skip(array, 2)`	Remaining items
`take()`	Takes first N items	`take(array, 3)`	First 3 items
`first()`	First item in array	`first(array)`	`Item1`
`last()`	Last item in array	`last(array)`	`ItemN`
`contains()`	Checks if array has value	`contains(array, value)`	`true/false`
`sort()`	Sorts array items	`sort(array)`	Sorted array
`filter()`	Filters array by condition	`filter(array, condition)`	Filtered array

🧪 Practical Examples of Array Functions

1. Join Email Addresses into One String

join(triggerBody()?['Emails'], ';')

Output: alice@example.com;bob@example.com;carol@example.com

2. Filter Open Tasks

filter(body('Get_Items'), item()?['Status'] == 'Open')

Use Case: Filter SharePoint list to show only open tasks.

3. Get the First Three Records

take(body('Get_Items'), 3)

Use Case: Only use the first 3 entries from a data source.

4. Merge Arrays and Remove Duplicates

union(variables('Array1'), variables('Array2'))

5. Check if Item Exists in Array

contains(variables('AssignedUsers'), 'john.doe@example.com')

✅ Best Practices for Collection and Array Functions

✅ Use length() to validate array size before looping.
✅ Apply union() or intersection() for deduplication or comparison.
✅ Avoid unnecessary loops—use filter() and select() instead.
✅ Use join() when converting arrays to strings for output or logs.
✅ Store results in Compose actions for easy debugging and reuse.

⚠️ Common Mistakes and How to Avoid Them

Problem	Cause	Fix
Flow fails on empty array	Accessing missing index	Use `length()` to check first
Repeating items after merge	Forgetting `union()`	Always use `union()` to deduplicate
Array to string errors	Using `+` to combine values	Use `join()` instead
Unexpected results from `filter()`	Bad condition syntax	Use `item()?['Field']` syntax correctly
Wrong item accessed	Index confusion	Use `first()`/`last()` or `take()/skip()` carefully

📘 Summary: When to Use Collection and Array Functions in Power Automate

Use collection and array functions in Power Automate when you need to:

Process grouped data dynamically
Filter, sort, or transform items in a list
Join array values for email or logs
Compare data from two sources
Access values by position (first, last, skip)

Curriculum

Collection and Array Functions in Power Automate