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power automate check if an item is in list

power automate check if an item is in list

4 min read 21-01-2025
power automate check if an item is in list

Power Automate offers several ways to check if an item exists within a list. This capability is crucial for various automation scenarios, from conditional logic in workflows to data validation. This article explores different approaches, detailing the most efficient methods and providing practical examples. Understanding these techniques allows you to build more robust and intelligent automations.

Methods for Checking List Membership in Power Automate

There isn't a single, dedicated "contains" action in Power Automate for checking list membership directly. However, several approaches effectively achieve this functionality, each with its strengths and weaknesses:

1. Using the indexOf() function (Recommended)

The indexOf() function is the most straightforward and efficient method for determining if an item is present in an array (list). This built-in function returns the index (position) of the item if found; otherwise, it returns -1.

How it works:

  1. Initialize: You'll start with your list and the item you want to check.
  2. Apply indexOf(): Use the indexOf() function within an expression to search the list. The syntax is indexOf(array, itemToFind). Replace array with your array variable and itemToFind with the item you're searching for.
  3. Conditional Logic: Use a Condition action to check the result. If indexOf() returns -1, the item isn't in the list; otherwise, it is.

Example:

Let's say you have a variable named myList containing a list of strings: ["apple", "banana", "orange"]. You want to check if "banana" exists.

  1. Expression: indexOf(variables('myList'), 'banana')
  2. Condition: Check if the result is is equal to 0 (or greater than -1). If true, "banana" is present.

Advantages: This method is concise, efficient, and easy to understand.

Disadvantages: Doesn't directly handle nested lists or complex data structures.

2. Using a Do until loop with a Condition (Less Efficient)

For more complex scenarios or if you need to perform actions based on finding the item's position, a loop can be used. However, this approach is generally less efficient than indexOf().

How it works:

  1. Initialize: Set up a loop counter variable and an indicator variable (e.g., a boolean).
  2. Loop: Iterate through your list using a Do until loop.
  3. Condition: Within the loop, use a Condition action to compare the current item to your target item.
  4. Update Indicator: If a match is found, set the indicator variable to true and exit the loop.
  5. Check Indicator: After the loop, check the indicator variable to determine if the item was found.

Example (Conceptual): This method is significantly more complex and verbose than the indexOf() method and is therefore not explicitly detailed here. It's recommended to use the indexOf() approach unless you have specific requirements mandating loop-based processing.

Advantages: Provides more control and allows for additional actions within the loop if needed.

Disadvantages: Less efficient than indexOf(), particularly for large lists. More complex to implement.

3. Using the Filter Array action (For more complex filtering)

The Filter Array action can filter your list based on a condition, effectively isolating the item you're seeking. While not directly checking for existence, it allows you to perform additional operations based on whether the item exists.

How it works:

  1. Filter Array: Use the Filter Array action with a condition that checks for equality with the item you're searching for.
  2. Check Length: Check the length of the resulting filtered array. If the length is greater than 0, the item exists.

Advantages: Useful when you also need to perform actions on the filtered items.

Disadvantages: Slightly less direct than indexOf(), requiring an extra step to check the length of the filtered array.

Choosing the Right Method

For most scenarios, the indexOf() function is the recommended approach. It's concise, efficient, and easily integrated into your Power Automate flows. The loop-based method should only be considered if you need more control or complex actions within the search process. The Filter Array action is best suited when you require additional operations on the matched item(s).

Practical Application: Example Workflow

Let's imagine a scenario where you receive emails containing order numbers. You want to check if those order numbers already exist in a SharePoint list.

  1. Get Items: Retrieve the list of existing order numbers from your SharePoint list. Store this in a variable called existingOrders.
  2. Get Email Body: Extract the order number from the incoming email. Store this in a variable named newOrderNumber.
  3. Check for Existing Order: Use the indexOf() function: indexOf(variables('existingOrders'), variables('newOrderNumber')) and store the result in a variable called orderExistsIndex.
  4. Conditional Logic: Add a Condition action: orderExistsIndex is greater than or equal to 0.
  5. Branches: Create two branches for the condition:
    • If True: The order number already exists. You could send a notification or take other appropriate action.
    • If False: The order number is new. You can proceed to add the order to the SharePoint list.

Remember to handle potential errors, such as incorrect data types or missing variables, for a more robust workflow. By using these methods effectively, you can build sophisticated Power Automate flows that handle data manipulation and validation with ease.

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