Merge CSV Files with Power Automate

A customer recently asked for an example of merging multiple CSV files into a single CSV file. Initially, we considered recommending the Encodian ‘Flowr‘ action ‘Excel – Merge Files‘; however, this action focuses on merging the structure and content of files, thus producing multiple worksheets.

Before you start

To test this flow, you will need some CSV files.  Feel free to use these example files:

• Customer-List-1.csv
• Customer-List-2.csv

Create the Power Automate Flow

1. Create a new ‘Instant cloud flow.‘

1.a. Flow name: Provide a name for your flow

1.b. Trigger: Select the ‘Manually trigger a flow‘ trigger action

1.c. Click ‘Create‘

2. Configure the ‘Manually trigger a flow‘ trigger action

2.a. Click ‘Add an input‘ > Select ‘File‘ > Enter the name ‘CSV File 1’

2.b. Repeat step 2.a. with the name ‘CSV File 2’

3. Add the Encodian ‘Excel – Merge Rows‘ action

3.a. Filename: File.csv and Output Format: CSV

3.b. Documents > Add New Item

• Filename – 1: Select ‘CSV File 1 name’ property provided by the ‘Manually trigger a flow’ trigger action
• File Content – 1: Select ‘CSV File 1 contentBytes’ property provided by the ‘Manually trigger a flow’ trigger action
• Sort Position – 1: 1
• Include Headers – 1: True

3.c. Documents > Add New Item

• Filename – 2: Select ‘CSV File 2 name’ property provided by the ‘Manually trigger a flow’ trigger action
• File Content – 2: Select ‘CSV File 2 contentBytes’ property provided by the ‘Manually trigger a flow’ trigger action
• Sort Position – 2: 2
• Include Headers – 2: False

3.d. Preserve First Row: True

The two CSV files have now been processed by the Encodian action. For this example, we will email a copy of the output CSV containing the merged CSV file to the user who triggered the flow.

Add the ‘Send an email notification (V3)‘ action and configure as follows:

• To: Enter an email address or select the ‘User email‘ property provided by the ‘Manually trigger a flow‘ trigger action
• Subject: Enter a relevant subject for the email
• Body: Enter a relevant body for the email
• Attachment: Select the ‘File Content’ property provided by the Encodian ‘Excel – Merge Rows’ action
• Attachment File Name: Select the ‘Filename’ property provided by the Encodian ‘Excel – Merge Rows’ action

NOTE: At the time of writing, there is a bug (well, several!) with the new Power Automate UI, where the ‘User email‘ property provided by the ‘Manually trigger a flow‘ trigger action is provided to the action encoded as a base64 string. Use the bae64ToString() expression to decode the value if required.

All done! Execute your flow…

The flow is now complete, so it can be tested using the example CSV files provided (or any two different CSV files).

Following the execution of the flow, an email will be received with the merged CSV file as an attachment.

Open the attachment to see the merged data.

Finally…

We hope this post provides a helpful guide to merging CSV files using Power Automate and the Encodian ‘Flowr‘ connector. If you require further assistance, please review the documentation on our support portal or raise a ticket with our support team.

Please share any feedback or comments – all are welcome.