Retrieve Files from Dataverse with a Power Apps Download Button

When you store files in a Dataverse file column, standard Power Apps controls like the PDF viewer or image control can display them, but they don't offer a straightforward way to download the binary file to the user's device. By composing a direct Web API URL and using the Download function, you can create a simple button that triggers a file download in the browser.

In this walk‑through you'll see a complete example: a project manager selects a contract in a gallery and clicks a button to download the associated PDF. All steps use a custom Dataverse table and environment variables for safe transportation between environments.

Scenario: Project Contracts Table

Imagine you're building a canvas app for a project management office. You have a Dataverse table named Project Contracts with these columns:

The table already contains a few records, each with a PDF attached in the file column.

Your canvas app shows a gallery of contracts, and each row has a Download button. When clicked, the button sends the PDF to the user's local machine.

1. Find Your Environment URL and Logical Names

The Web API endpoint follows this structure:

https://<environment_url>/api/data/v9.2/<table_logical_name>(<record_guid>)/<column_logical_name>/$value

You need three pieces of information.

Environment URL

Open the Power Platform admin center, select your environment, and copy the URL (e.g., org12345.crm.dynamics.com). Prepend https:// when building the final URL.

Table Logical Name

In a browser, navigate to https://<environment_url>/api/data/v9.2. The JSON result lists all entity sets. Look for the entry that matches your table – for example nar_projectcontracts.

Record GUID

Use the Web API to get a list of records from your table:

GET https://<environment_url>/api/data/v9.2/nar_projectcontracts

In the response, pick the nar_contractid value for the contract you want to download. Dataverse stores the primary key as a GUID.

Column Logical Name

Retrieve a single record to see its column names:

GET https://<environment_url>/api/data/v9.2/nar_projectcontracts(<guid>)

The file column appears as nar_contractfile. Add /$value at the end to request the binary content.

2. Build the Download Button

Inside Power Apps Studio, add a Button control to your screen. Set its OnSelect property to the following Power Fx code:

Download(
  $"https://{LookUp('Environment Variable Values',
      'Environment Variable Definition'.'Display Name' = "Environment URL",
      Value
  )}/api/data/v9.2/nar_projectcontracts({Gallery1.Selected.'Contract ID'})/nar_contractfile/$value"
)

This code assumes you have a gallery named Gallery1 bound to the Project Contracts table, and that an environment variable named Environment URL holds your environment URL.

3. Use an Environment Variable for Portability

Hard‑coding the environment URL ties your app to a single environment. Instead, create a Text environment variable inside a solution:

1. In make.powerapps.com, open the solution that contains your app.
2. Click New > Environment variable.
3. Set Display name to Environment URL.
4. Choose Data type = Text.
5. In the Current Value field, paste your environment URL (e.g., https://org12345.crm.dynamics.com – include the protocol).

Back in the canvas app, add the Environment Variable Definitions and Environment Variable Values tables as data sources (they come from the environment’s default solution). Then use the LookUp pattern shown above to retrieve the value.

4. Test the Download

Publish the app. When you click the button, the browser should download the file. If nothing happens, check:

• The record GUID is correct and hasn’t been deleted.
• The column logical name matches the file column (not a text or image column).
• The environment variable is populated and the app can access its table.
• Your user account has Read permission on the table and the file column.

Performance and Security Considerations

• The Download function is not delegable, but it only runs on the selected record, so performance is fine.
• File size matters: Dataverse file columns can hold up to 128 MB. Very large files may take a moment to download; consider adding a loading indicator.
• The Web API endpoint respects your role‑based security. Users who cannot read the record or the file column will receive a 403 or 404 response.

Common Mistakes

If you encounter an error, start by testing the URL directly in a browser. If it works there, the issue is likely in your Power Fx code or data sources.

Final Recommendation

The approach shown here is simple and effective for downloading files from Dataverse file columns. Always use environment variables for any environment‑specific values (URL, maybe table names) to make your app solution‑ready. For complex scenarios—like downloading multiple files at once or handling non‑PDF types—the same pattern works with any file column that returns binary data via $value.

References

• Original article by Matthew Devaney: Power Apps: Download File From Dataverse File Column
• Microsoft Learn: Retrieve a table row using the Web API
• Microsoft Learn: Perform operations using the Web API