Скачать или смотреть How to Make a POST Request with an Image Using Python

Learn how to send an image through a POST request to a Flask server using Python with the `requests` library.
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This video is based on the question https://stackoverflow.com/q/70272903/ asked by the user 'James Watson' ( https://stackoverflow.com/u/13677422/ ) and on the answer https://stackoverflow.com/a/70273024/ provided by the user 'yuwan' ( https://stackoverflow.com/u/16604732/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Make a POST Request with an Image Using Python

In the world of web development, sending files using HTTP requests is a common task. One such scenario arises when you need to upload an image file to a server. You might be implementing a feature in your Flask web application that requires this functionality, and you want to use Python to make it happen. If you've tried using cURL and found it easy but struggled with the Python requests library, you're not alone. In this post, we will clearly explain how to achieve this and troubleshoot some common issues.

The Problem

Setting up a POST request in Python to send an image file to a Flask server can be tricky, especially for those who are new to the requests library. A user experienced an issue where they received the HTML of the site instead of the JSON response they were expecting. This often happens due to incorrect formatting of the request or misnamed parameters when sending files.

Example Scenario

Let's look at the code that was causing confusion:

[[See Video to Reveal this Text or Code Snippet]]

While the code seems to set up the request correctly, the response wasn’t what the user was expecting. Instead of receiving a JSON object, they got a 200 OK status with HTML content.

The Solution

To successfully send an image file and receive the desired response from your Flask server, we need to ensure that the file is sent with the correct key. In most scenarios, the key should match what the Flask application is configured to accept for file uploads. Here’s how to fix the initial attempt:

Correct Code Example

Replace the faulty approach with the following snippet, which simplifies the files parameter and ensures the correct key is used:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Solution:

File Opening: We're opening the image file in binary mode ('rb'), which is essential for image uploads.

Using the Correct Key: Use 'file' as the key in your files dictionary. This key should correspond to what your Flask application expects when handling file uploads.

Executing the POST Request: The call to requests.post() sends the file correctly, enabling the server to process it appropriately.

Handling Responses

Once you send the request, you can check the response like so:

Print Response: print(r.text) displays the server's response to your upload, which should be JSON if everything is set up correctly on the server-side.

Status Code: print(r.status_code) should return 200 if the request was successful.

Conclusion

Uploading files, specifically images, to a Flask server using Python can be done efficiently with the correct parameters. If you've been frustrated with the requests library, just remember to align the key names in your files dictionary with what your Flask endpoint expects. Give the revised code a try, and you'll be well on your way to successfully handling image uploads in your web applications.

If you have any further questions or want to delve deeper into Flask or Python requests, feel free to reach out. Happy coding!