> ## Documentation Index > Fetch the complete documentation index at: https://forest-docs-cli-reference-headless-commands.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Generate signed urls to display S3 files in a smart field **Context**: As a user I want to be able to preview files from an S3 bucket thanks to secure signed urls. **Example**: I have a collection `places` that has a `pictures` field which is an array of strings containing the file name of files stored on a s3 bucket. In a smart field called `s3pictures` I return the value of calls made to S3 to get signed urls for the files whose name is present in the `pictures` field. ### Implementation First you need to implement the function to get the signed urls from s3. We use the `aws-sdk` npm package to connect to the bucket storing the pictures. `services/s3-helper.js` You can then use the default file viewer widget settings to preview the pictures.