REST Client is a convenience tool to help sending HTTP request to the server for ruby. We are keep using the 1.6.7 version before, but we found fastlane’s gem required the lowest rest-client version is 1.8.0. So we thought maybe it’s time to update to use latest rest-client version now. And I’d like to memo how we successfully migrate to use the 2.1.0 rest-client in this article.

At first, I thought simply update rest-client gem version would be enough. But then I got a 400 BAD Request error for it. After doing some research, it seems this is because there is something wrong in the request body part.

Let me post our 1.6.7 version script at here:

url = "http://ourlink/api/post"
request_body = [
	['key_1', 'value_1'],
	['key_2', 'value_2'],
	['files', File.new('file_1_path', 'r')],
	['files', File.new('file_2_path', 'r')],
]
header = {
	'custom_token' => 'our_token_str'
}
res = RestClient.post(url, request_body, header)

It’s easier to find the wrong part would be the request_body format. It seems start from 2.x, we couldn’t directly use []. Then we tried another format:

request_body = {
	'key_1' => 'value_1',
	'key_2' => 'value_2',
	'files' => File.new('file_1_path', 'r'),
	'files' => File.new('file_2_path', 'r'),
}

This time we could successfully send the request, but after checking the response, we found there is only one file upload successfully. One of our files is missing. Yeah, the file_2_path replace the file_1_path. That is really not what we want. 😢

Then, we tried to change the body part as:

request_body = {
	'key_1' => 'value_1',
	'key_2' => 'value_2',
	'files' => [File.new('file_1_path', 'r'), File.new('file_2_path', 'r')]
}

Then we start getting the 500 Internal Server error now. It shows:

{"result":false,"errorType":"NumberFormatException","errorMessage":"For input string: \"\"","statusCodeCode":500}

By reading the rest-client Query Parameters guideline, it seems if we directly pass array to a key, it will be transferred as url?files[]=file_1&files[]=file_2. But at here, we want the request to be url?files=file_1&files=file_2.

For getting url?files=file_1&files=file_2 request, rest-client 2.x provide new ParamsArray. So, changing the body part to ⬇️ will fix this 500 issue.

request_body = RestClient::ParamsArray.new([
	[:key_1, 'value_1'],
	[:key_2, 'value_2'],
	[:files, File.new('file_1_path', 'r')],
	[:files, File.new('file_2_path', 'r')],
])

Now, the request should be successfully sent, and the request body format should be correct. 🎉

Reference

• https://github.com/rest-client/rest-client
• https://www.rubydoc.info/gems/rest-client/RestClient/ParamsArray