File Upload and Download via the Data API

Beginner

Upload binary files into FileMaker container fields and download container content using the Data API, including streaming large files.

What you'll learn

  • How to upload a file to a container field with multipart/form-data
  • How container field values appear in GET responses
  • How to download container content using the provided URL
  • How to handle large files without loading them fully into memory

Container fields store binary data -- images, PDFs, audio files. The Data API provides a dedicated upload endpoint that accepts multipart/form-data, and container field values in GET responses include a URL you can use to fetch the binary content. Understanding both directions prevents the common mistake of trying to base64-encode files in JSON.

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Uploading a file to a container field

Use a POST to the container upload endpoint with Content-Type: multipart/form-data. The form field must be named "upload". The record must already exist -- create it first, then upload.

HTTP
// Upload a PDF to the "Document" container field on record 14
POST /fmi/data/v1/databases/Projects/layouts/Documents/records/14/containers/Document/1
Content-Type: multipart/form-data; boundary=----Boundary

------Boundary
Content-Disposition: form-data; name="upload"; filename="contract.pdf"
Content-Type: application/pdf

<binary PDF data>
------Boundary--
Triggering FileMaker Scripts from the Data APIData API Versioning and Compatibility

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