Incorrect Handling of Multiple Form Files with Same Key in JSON Output

[RamDurgaSai]

When I use the curlconverter to convert a complex curl command to JSON, specifically a command that uploads multiple files using the same form field name (key), the JSON output doesn't capture all the files. Instead, it overwrites the previous file with the last one having the same key.

Example

curl -F files=@picture1.jpg -F files=@picture2.jpg -F "story=<hugefile.txt" --form-string "name=content" example.com/upload.cgi

Output

{
    "url": "http://example.com/upload.cgi",
    "raw_url": "http://example.com/upload.cgi",
    "method": "post",
    "files": {
        "files": "picture2.jpg",
        "story": "hugefile.txt"
    },
    "data": {
        "name": "content"
    }
}

Demonstrating the Problem with JavaScript:

When converting to other languages or libraries, such as JavaScript's Fetch API, multiple files for the same key are handled correctly:

const form = new FormData();
form.append('files', File(['<data goes here>'], 'picture1.jpg'));
form.append('files', File(['<data goes here>'], 'picture2.jpg'));
form.append('story', File(['<data goes here>'], 'hugefile.txt'));
form.append('name', 'content');

fetch('http://example.com/upload.cgi', {
  method: 'POST',
  body: form
});

As illustrated, the correct approach involves using multiple entries for each file under the files key.

[verhovsky]

What are you using the JSON format for? Because if you used a JSON parser on this

{
    "files": {
        "files": "picture1.jpg",
        "files": "picture2.jpg",
        "story": "hugefile.txt"
    }
}

it would also just ignore the "files": "picture1.jpg", line. But I agree that it would be better to warn about this situation or generate JSON with a duplicate key than silently dropping a key.

[RamDurgaSai]

I'm utilizing this in a No Code API Testing platform.

[RamDurgaSai]

Rather than having duplicate keys in the JSON—since all JSON parsers override them—I believe it is better to use an array for that key instead of a string.