CODEWITHSUNDEEP
imagefile-uploadcurl
user2497586
user2497586

Reputation:

How to include an image in an http POST request

I'm trying to make a POST request from the command line to my Flask app, and I want it to include an image. But I don't know how to include it with the command. I've only used strings as data successfully.

So, if my POST request looks like this:

 curl -i -H "Content-Type: application/json" -X POST -d '{"username":"user1", "password":"password", "image":##What do I put here?##}' http://localhost:5000/my_app/api/users

I don't know what to put in that image part of the JSON. I'm tagging flask in this question because it might be a specific answer with regards to flask.

I would like to include an actual image here, and then on the Flask side of things, put the image in a folder of the app where all the uploads go, then save the path to the image in the database for later access. But, to do that, I need to know how to send an image in the first place. Any thoughts?

Upvotes: 0

Views: 3775

Answers (1)

Paolo Casciello
Paolo Casciello

Reputation: 8202

Seems you're mixing things up here.

From your example seems you want to upload an image in a JSON object. This is generally bad for 2 reasons:

  • Overhead: the image data should be encoded in printable characters, e.g. using base64. This creates a huge overhead on the data itself causing the JSON decoder to slow down.

  • Testing: You can't try this using curl on the commandline. You should make some command line utility to test the request.

HTTP knows about data uploads. So to mantain the JSON structure without the slowdown of above, you should upload your image as traditional data upload using a field, and another field for the JSON data structure. Using curl this is achieved with the -F option.

curl -i [email protected] -Fdata='{"username":"user1", "password":"password"}'  http://localhost:5000/my_app/api/users

With the above command you are sending an HTTP POST with a file upload named filedata and a 'data` field containing your 'JSON' payload to parse in the receiving view handler.

You must use 2 HTTP fields because in HTTP upload you're using multipart encoding.

Behind the scenes

You're sending the image contents encoded in base64 but since the data is decoded by the application framework knowing exactly what to do (JSON parse must figure it out while parsing) it's a lot faster.

Upvotes: 1

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