StringError("text was not valid unicode")

[oshinowo-stephen]

So I was trying to use the multipart Iron example from the source... But the thing is when I upload a file specifically an image file it responds back with an error and doesn't respond back with the data fields... the error is stating this

Field "myfile" has 1 entries:
0: Some("1!.jpg") (Some(Mime(Image, Jpeg, []))):
ERROR 2018-08-12T20:32:00Z: iron::iron: Error handling:
Request {
    url: Url { generic_url: "http://localhost:3000/req/send" }
    method: Post
    remote_addr: V4(127.0.0.1:52494)
    local_addr: V4(127.0.0.1:3000)
}
Error was: Custom { kind: InvalidData, error: StringError("text was not valid unicode") }

I don't fully understand what this error means and why i'm getting it... but I feel like i'm doing something wrong but i'm not sure what though.

[abonander]

What are you using to submit the request? Can you capture the raw request body? It's trying to interpret some binary field in the request as text but the image file seems to be uploaded successfully, based on the output you gave (its filename and media-type are printed).

[oshinowo-stephen]

Yes that's why I'm confused why it's not printing the data on screen... also i'm still confused why it's printing with that error. Also i'm using a HTML form to submit the request, that looks something like this.

<form action="/req/send" enctype="multipart/form-data" method="post">
  <input type="file" name="myfile" id="file">
  <input type="submit" value="Submit">
</form>

[abonander]

Looking at the code, the error is occurring when trying to write the file contents to the response, but I haven't found which component is actually trying to parse the file contents as a string.

[abonander]

@GitStonic nevermind capturing the request body, I just need to find where it's trying to parse the file as a string. It's somewhere in the call tree of process_entries(). I want to say it might be Hyper since the default content type for Iron responses is text/plain and Hyper might be trying to verify that.

[abonander]

What version of Iron are you using, anyway?

[oshinowo-stephen]

I believe i'm using the latest version of Iron 0.6.0 to be exact.

[abonander]

@GitStonic just to test an assumption, does the error still occur if you set the content type of the response to something like application/octet-stream?

[oshinowo-stephen]

yes the error still occurs after setting the content-type to application/octet-stream

[abonander]

@GitStonic I started to get frustrated because I could not find that error string anywhere within multipart, Iron or Hyper. That's because it originates in the Windows stdio handling code in the Rust stdlib. You see, Windows doesn't like non-Unicode sequences being printed to the console, even though std exposes it as a byte-oriented interface. Unfortunately, that's exactly what StdoutTee is doing here.

I see a few possible solutions:

• Don't print non-text file fields to stdout (text files still not guaranteed to be valid Unicode)
• Don't print any files
• For file fields, print some text representation of their contents instead (hash, hexadecimal, base-64?)

[oshinowo-stephen]

I see... I will try those options, Thank you for your time and effort for me. Really appreciate it.

[abonander]

I need to fix these examples as well so I'm looking for opinions on the best approach. I wanted it to print the fields to stdout somehow but I dunno if I want to pull in another crate just for hashing/base64 conversion.

[abonander]

I've submitted a PR to rust-lang/rust to make the error message more specific and to document the portability hazard. I still have to fixup the examples, I'll get to that sometime.