README
U
Callback
E
MultipartError
- ::FormForm::Form
- ::next_partForm::next_part
- ::content_typeFormPart::content_type
- ::filenameFormPart::filename
- ::headersFormPart::headers
- ::nameFormPart::name
- ::FormWriterFormWriter::FormWriter
- ::boundaryFormWriter::boundary
- ::content_typeFormWriter::content_type
- ::finishFormWriter::finish
- ::write_fieldFormWriter::write_field
- ::write_fileFormWriter::write_file
- ::write_jsonFormWriter::write_json
- ::write_partFormWriter::write_part
- ::ReaderReader::Reader
- ::next_partReader::next_part
- ::WriterWriter::Writer
- ::finishWriter::finish
- ::write_partWriter::write_part
- ::write_readerWriter::write_reader
V
parse_header_value

multipart

A streaming multipart reader/writer library integrated with `moonbitlang/async`.

multipart

form-data

Download zip

Author

Yoorkin

Version

0.1.2

License

Apache-2.0

Repository

github.com/Yoorkin/multipart

Last updated

3 hours ago

Downloads

Dependencies

moonbitlang/async0.22.1

#multipart

A streaming multipart reader/writer library integrated with moonbitlang/async.

Reader/Writer handle MIME multipart, Form/FormWriter handle multipart/form-data. Part bodies are streamed as raw bytes.

#Examples

Upload a field and a file through an HTTP client:

///|
async fn upload(client : @http.Client, file : &@io.Reader) -> @http.Response {
  let form = @multipart.FormWriter(client)
  client.request(Post, "/upload", extra_headers={
    "Content-Type": form.content_type(),
  })
  form.write_field("description", "Release archive")
  form.write_file("archive", filename="release.zip", file)
  form.finish()
  client.end_request()
}

Read an upload using the request's Content-Type and copy its archive part:

///|
async fn receive_archive(
  source : &@io.Reader,
  target : &@io.Writer,
  content_type : String,
) -> Unit {
  let (media_type, parameters) = @multipart.parse_header_value(content_type)
  guard @http.CaseInsensitiveString(media_type) == "multipart/form-data" else {
    raise Failure("expected multipart/form-data")
  }
  guard parameters.get("boundary") is Some(boundary) else {
    raise Failure("missing multipart boundary")
  }
  let form = @multipart.Form(source, boundary~)
  while form.next_part() is Some(part) {
    if part.name() == "archive" {
      target.write_reader(part)
    }
  }
}

next_part() discards unread content from the previous part. Process parts sequentially; finish() leaves the underlying writer open.

For other multipart subtypes, use Reader/Writer with your own headers:

///|
async fn copy_parts(source : &@io.Reader, target : &@io.Writer) -> Unit {
  let reader = @multipart.Reader(source, boundary="incoming")
  let writer = @multipart.Writer(target, boundary="outgoing")
  while reader.next_part() is Some((headers, body)) {
    writer.write_reader(headers~, body)
  }
  writer.finish()
}

Choose an output boundary that does not occur in the content. FormWriter creates a random boundary automatically.

#Tests

See fixtures for specification sources and snapshot tests.

Callback

source

type Callback = async (&@moonbitlang/async/io.Writer
Writer) -> Unit

MultipartError

source

pub suberror MultipartError {
  MultipartError(String)
} derive(@moonbitlang/core/debug.Debug
Debug)

Form

source

type Form

Streams the parts of a multipart/form-data body in their original order.

Form::Form

source

fn Form::Form(source : &@moonbitlang/async/io.Reader
Reader, boundary~ : String) -> Form raise MultipartError

Form::next_part

source

async fn Form::next_part(self : Form) -> FormPart?

Advancing discards any unread bytes from the previous part. Bodies remain bytes: charset and Content-Transfer-Encoding are not decoded. Nested multipart bodies are exposed as parts and can be traversed with Reader.

FormPart

source

type FormPart

impl Reader for FormPart

async fn _direct_read(self : FormPart, buffer : FixedArray[Byte], offset~ : Int, max_len~ : Int) -> Int

source

fn _get_internal_buffer(self : FormPart) -> @moonbitlang/async/io.ReaderBuffer
ReaderBuffer

source

FormPart::content_type

source

fn FormPart::content_type(self : FormPart) -> String

Returns the full Content-Type value, including any charset parameter. RFC 7578 §4.4 specifies text/plain when the header is absent.

FormPart::filename

source

fn FormPart::filename(self : FormPart) -> String?

Returns the supplied filename. When saving a file, the caller must discard directory components and choose a suitable local name (RFC 7578 §4.2). Percent escapes remain literal because multipart/form-data does not identify whether a filename uses the optional percent-encoding convention.

FormPart::headers

source

fn FormPart::headers(self : FormPart) -> Map[@moonbitlang/async/http.CaseInsensitiveString
CaseInsensitiveString, String]

FormPart::name

source

fn FormPart::name(self : FormPart) -> String

FormWriter

source

type FormWriter

FormWriter::FormWriter

source

fn FormWriter::FormWriter(target : &@moonbitlang/async/io.Writer
Writer) -> FormWriter raise MultipartError

Create a form writer with a boundary containing 192 bits of platform entropy.

FormWriter::boundary

source

fn FormWriter::boundary(self : FormWriter) -> String

The generated boundary, for constructing a matching reader or MIME header.

FormWriter::content_type

source

fn FormWriter::content_type(self : FormWriter) -> String

The HTTP Content-Type for the generated form body.

FormWriter::finish

source

async fn FormWriter::finish(self : FormWriter) -> Unit

FormWriter::write_field

source

async fn FormWriter::write_field(self : FormWriter, name : String, value : String) -> Unit

Write a UTF-8 text field, preserving the value's line endings.

FormWriter::write_file

source

async fn FormWriter::write_file(self : FormWriter, name : String, filename? : String, content_type? : String, file : &@moonbitlang/async/io.Reader
Reader) -> Unit

Stream a file without closing its reader. An unspecified content type uses application/octet-stream; filename is optional (RFC 7578 sections 4.2–4.4).

FormWriter::write_json

source

async fn FormWriter::write_json(self : FormWriter, name : String, value : Json) -> Unit

Write a JSON field with Content-Type application/json.

FormWriter::write_part

source

async fn FormWriter::write_part(self : FormWriter, headers~ : Map[@moonbitlang/async/http.CaseInsensitiveString
CaseInsensitiveString, String], callback : async (&@moonbitlang/async/io.Writer
Writer) -> Unit) -> Unit

Write a part with caller-supplied MIME headers.

Reader

source

type Reader

A sequential, streaming MIME multipart reader (RFC 2046 section 5.1.1). The source must be limited to the enclosing message body.

Reader::Reader

source

fn Reader::Reader(source : &@moonbitlang/async/io.Reader
Reader, boundary~ : String) -> Reader raise MultipartError

boundary is the decoded Content-Type parameter, without quotes or --.

Reader::next_part

source

async fn Reader::next_part(self : Reader) -> (Map[@moonbitlang/async/http.CaseInsensitiveString
CaseInsensitiveString, String], &@moonbitlang/async/io.Reader
Reader)?

Read the next part's headers and a reader limited to its body. Advancing drains the previous part; retained readers then return EOF. Preamble and epilogue are ignored. Bodies are returned without transfer decoding. Header folding is unfolded; repeated names are comma-joined as in @http.Headers. Calls on this reader and its current part must be made sequentially.

Writer

source

type Writer

Writer::Writer

source

fn Writer::Writer(target : &@moonbitlang/async/io.Writer
Writer, boundary~ : String) -> Writer raise MultipartError

Create a multipart writer. The caller must choose a boundary that does not occur as a delimiter in any part (RFC 2046 section 5.1.1).

Writer::finish

source

async fn Writer::finish(self : Writer) -> Unit

Write the closing delimiter without closing the underlying writer. Repeated calls have no effect.

Writer::write_part

source

async fn Writer::write_part(self : Writer, headers~ : Map[@moonbitlang/async/http.CaseInsensitiveString
CaseInsensitiveString, String], callback : async (&@moonbitlang/async/io.Writer
Writer) -> Unit) -> Unit

Write a part without buffering its body. Call parts sequentially, and use the callback's writer only until the callback returns.

Writer::write_reader

source

async fn Writer::write_reader(self : Writer, headers~ : Map[@moonbitlang/async/http.CaseInsensitiveString
CaseInsensitiveString, String], source : &@moonbitlang/async/io.Reader
Reader) -> Unit

Stream a reader's remaining bytes as one part, leaving both streams open.

parse_header_value

source

fn parse_header_value(value : String) -> (String, Map[@moonbitlang/async/http.CaseInsensitiveString
CaseInsensitiveString, String]) raise MultipartError

Parses an unfolded MIME field value, such as Content-Type or Content-Disposition. The main value is a token or type/subtype; parameter names are case-insensitive. Main values and parameter values retain their case. Comments are ignored and quoted pairs are unescaped; percent escapes and extended parameters stay raw. Grammar: RFC 2045 §5.1 and RFC 2183 §2.

Source Files

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multipart

#multipart

#Examples

#Tests

#Callback

#MultipartError

#Form

#Form::Form

#Form::next_part

#FormPart

#FormPart::content_type

#FormPart::filename

#FormPart::headers

#FormPart::name

#FormWriter

#FormWriter::FormWriter

#FormWriter::boundary

#FormWriter::content_type

#FormWriter::finish

#FormWriter::write_field

#FormWriter::write_file

#FormWriter::write_json

#FormWriter::write_part

#Reader

#Reader::Reader

#Reader::next_part

#Writer

#Writer::Writer

#Writer::finish

#Writer::write_part

#Writer::write_reader

#parse_header_value

Source Files

Callback

MultipartError

Form

Form::Form

Form::next_part

FormPart

FormPart::content_type

FormPart::filename

FormPart::headers

FormPart::name

FormWriter

FormWriter::FormWriter

FormWriter::boundary

FormWriter::content_type

FormWriter::finish

FormWriter::write_field

FormWriter::write_file

FormWriter::write_json

FormWriter::write_part

Reader

Reader::Reader

Reader::next_part

Writer

Writer::Writer

Writer::finish

Writer::write_part

Writer::write_reader

parse_header_value