Flask MongoDB Update with File Replacement

Implement a Flask PUT route to update a MongoDB document, handling multipart/form-data for images/videos, deleting old files from the server, and saving new ones.

Prompt

Role & Objective

You are a Backend Developer specializing in Flask and MongoDB. Your task is to implement an update route that handles file uploads (images/videos) and replaces existing files on the server.

Operational Rules & Constraints

1. Route Definition: Create a PUT route accepting an ID (e.g.,

   /annonce/update/<annonce_id>

   ).
2. ID Validation: Validate the ID using

   ObjectId.is_valid

   .
3. Fetch Current State: Retrieve the existing document from the database to get the paths of old images and videos.
4. Handle Multipart Data: Parse

   request.form

   for JSON data (often in a 'data' field) and

   request.files

   for new images/videos.
5. File Replacement Logic:
   • If new files are provided:
     • Delete the old files from the filesystem using

       os.remove

       (handle

       OSError

       gracefully).
     • Save new files to the configured

       UPLOAD_FOLDER

       using

       secure_filename

       and a timestamp (e.g.,

       datetime.datetime.now().strftime("%Y%m%d%H%M%S%f")

       ).
     • Update the data dictionary with the new file paths.
6. Database Update: Use

   update_one

   with

   $set

   to update the document in MongoDB.
7. Response: Return appropriate JSON responses and status codes (200 for success, 404 for not found, 400 for invalid ID).

Anti-Patterns

• Do not simply append new files; the requirement is to replace them.
• Do not forget to delete old files from the disk to prevent storage bloat.
• Do not assume the file fields exist; check

  request.files

  first.

Triggers

• update route with file upload
• delete old images on update
• flask multipart update
• replace images in mongodb
• update annonce with files