Hi Rodrigo,

Thank you for starting this discussion.

You might be interested to know that we are working on a framework to create connections from Wolfram Language to external APIs in an easy way and share them as resources.

Please let me know if you want to have early access to test it. Thanks!

@Mike,

Thanks Mike. Do you mind leaving your info here in this form?

https://www.wolframcloud.com/obj/christianp/tmp/SCFrameworkBetaTestingList

Thanks

Here is a better toy code using httpbin.org (cool service!).

HTTPRequest["https://httpbin.org/anything",
      <|
      Method->"POST"
      ,"Body" -> {
          "text" -> "Diacritics test: àáâãäåçèéêëìíî"
          , "attachment" -> File[Export["image.png", Graphics@Circle[], ImageSize-> 1]]
         }
        |>
     ]//URLRead[#, "BodyBytes"]&//FromCharacterCode

As you can see, "text" is broke:

text: "Diacritics test: \ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd"

If you comment the attachment part, we get it right:

text: "Diacritics test: \u00e0\u00e1\u00e2\u00e3\u00e4\u00e5\u00e7\u00e8\u00e9\u00ea\u00eb\u00ec\u00ed\u00ee"

Like Arnoud, I can't test directly with the API you're using, but some local experimentation suggests this might work:

In[2]:= HTTPRequest[
"https://api.mailgun.net/v3/mydomain.com/messages", <|
Method -> "POST", "User" -> "api:MY_API_KY", 
"Body" -> {"from" -> "test@mydomain.com", "to" -> "me@me.com", 
"subject" -> "With Attachment", 
"text" -> <|
"Content" -> 
StringToByteArray["Diacritics test: àáâãäåçèéêëìíî"], 
"MIMEType" -> "text/plain;charset=utf-8"|>, 
"attachment" -> File[FindFile["ExampleData/mathematica.pdf"]]}|>,
CharacterEncoding -> "UTF8"] // URLRead[#, "Body"] &

When character encodings are an issue I generally find it better to manually encode the relevant portions of a request with StringToByteArray. The documentation for HTTPRequest suggests a ByteArray should work, but unfortunately it doesn't:

In[2]:= HTTPRequest[
"https://api.mailgun.net/v3/mydomain.com/messages", <|
Method -> "POST", "User" -> "api:MY_API_KY", 
"Body" -> {"from" -> "test@mydomain.com", "to" -> "me@me.com", 
"subject" -> "With Attachment", 
"text" -> <|
"Content" -> 
StringToByteArray["Diacritics test: àáâãäåçèéêëìíî"], 
"MIMEType" -> "text/plain;charset=utf-8"|>, 
"attachment" -> File[FindFile["ExampleData/mathematica.pdf"]]}|>,
CharacterEncoding -> "UTF8"] // URLRead[#, "Body"] &

During evaluation of In[2]:= General::erropts: The value{{from,Automatic} ->test@mydomain.com, {to,Automatic} ->me@me.com, {subject,Automatic} -> With Attachment, {text,text/plain;charset=utf-8,58b41feb-7b98-458f-afc8-8fd836c4461e} ->ByteArray[45 bytes], {attachment,Automatic}->File[/Applications/Mathematica 12.2.app/Contents/Documentation/English/System/ExampleData/mathematica.pdf]}specified for the option MultipartElements is invalid.

Out[2]= Failure["ConnectionFailure", 
Association[
"URL" -> "https://api.mailgun.net/v3/mydomain.com/messages",
"MessageTemplate" -> "Unable to perform the request.", 
"MessageParameters" -> Association[], 
"HTTPRequest" -> HTTPRequest[
"https://webhook.site/efe31524-3df5-4d3f-8d80-b5be37df83b0", 
Association[
Method -> "POST", "User" -> "api:MY_API_KY", 
"Body" -> {"from" -> "test@mydomain.com", "to" -> "me@me.com", 
"subject" -> "With Attachment", 
"text" -> Association[
"Content" -> ByteArray[{68, 105, 97, 99, 114, 105, 116, 105, 
99, 115, 32, 116, 101, 115, 116, 58, 32, 195, 160, 195, 
161, 195, 162, 195, 163, 195, 164, 195, 165, 195, 167, 195,
168, 195, 169, 195, 170, 195, 171, 195, 172, 195, 173, 
195, 174}], "MIMEType" -> "text/plain;charset=utf-8"], 
"attachment" -> File["/Applications/Mathematica12.2.app/Contents/Documentation/English/System/ExampleData/mathematica.pdf"]}], CharacterEncoding -> "UTF8"], "Counter" -> 1]]

Hi Arnoud, thanks for your suggestion. But in this case the problem is not to Read the request, the problem is that it sends the text data wrong when URLRead is executed. It's like when I pass the File, some encode changes.

I can't reproduce this (because of the API key required), but try doing it this way (I have has success with it in other cases):

request = HTTPRequest[...]
response = URLRead[request]
ImportByteArray[response["BodyByteArray"]]

(Or something equivalent based on working with the ByteArray and not text directly.)