Struct Part 

pub struct Part { /* private fields */ }

Available on crate features http and multipart only.

A single part of a multipart Form.

Built via text, bytes, stream, or file. Customise with with_file_name, try_with_mime_str, with_content_size, or with_headers.

Implementations

impl Part

pub fn text<V>(value: V) -> Part

where V: Into<Cow<'static, str>>,

Create a text part.

pub fn bytes<B>(value: B) -> Part

where B: Into<Bytes>,

Create a part from raw bytes.

pub fn stream<S, O, E>(stream: S) -> Part

where S: Stream<Item = Result<O, E>> + Send + 'static, O: Into<Bytes> + 'static, E: Into<Box<dyn Error + Send + Sync>> + 'static,

Create a streaming part. The content size is unknown unless set explicitly via with_content_size.

pub async fn file<P>(path: P) -> Result<Part, Error>

where P: AsRef<Path>,

Create a part from a file. The filename is taken from the path’s last component, the MIME type is inferred from the extension (falling back to application/octet-stream), and the content size is read from filesystem metadata.

Filenames are converted to UTF-8 using lossy replacement of any non-UTF-8 bytes (relevant on Unix where filenames are arbitrary byte sequences). If you need to preserve non-UTF-8 names verbatim, build the Part yourself with Part::file and override the name via Part::with_file_name from a known UTF-8 source.

The reported content_size is taken from filesystem metadata at the moment of the call. Concurrent writers that change the file size between this call and the body being sent can desynchronise the advertised Content-Length from the actually-streamed bytes; avoid passing a path to a file that may be modified mid-flight.

pub fn with_file_name(self, file_name: impl Into<Cow<'static, str>>) -> Part

Filename used in the part’s Content-Disposition header.

Accepts anything that converts into Cow<'static, str> — &'static str literals, owned String, or an explicit Cow::Owned/Cow::Borrowed.

pub fn set_file_name( &mut self, file_name: impl Into<Cow<'static, str>>, ) -> &mut Part

Filename used in the part’s Content-Disposition header.

Accepts anything that converts into Cow<'static, str> — &'static str literals, owned String, or an explicit Cow::Owned/Cow::Borrowed.

pub fn maybe_with_mime(self, mime: Option<Mime>) -> Part

The part’s Content-Type, as a parsed Mime.

with_*/set_* set, without_*/unset_* clear any previously-set value.

pub fn maybe_set_mime(&mut self, mime: Option<Mime>) -> &mut Part

The part’s Content-Type, as a parsed Mime.

with_*/set_* set, without_*/unset_* clear any previously-set value.

pub fn with_mime(self, mime: Mime) -> Part

The part’s Content-Type, as a parsed Mime.

with_*/set_* set, without_*/unset_* clear any previously-set value.

pub fn set_mime(&mut self, mime: Mime) -> &mut Part

The part’s Content-Type, as a parsed Mime.

with_*/set_* set, without_*/unset_* clear any previously-set value.

pub fn without_mime(self) -> Part

The part’s Content-Type, as a parsed Mime.

with_*/set_* set, without_*/unset_* clear any previously-set value.

pub fn unset_mime(&mut self) -> &mut Part

The part’s Content-Type, as a parsed Mime.

with_*/set_* set, without_*/unset_* clear any previously-set value.

pub fn try_with_mime_str(self, mime_str: &str) -> Result<Part, FromStrError>

The part’s Content-Type parsed from a string such as "image/png". Generates try_with_mime_str / try_set_mime_str companions returning Result.

pub fn try_set_mime_str( &mut self, mime_str: &str, ) -> Result<&mut Part, FromStrError>

The part’s Content-Type parsed from a string such as "image/png". Generates try_with_mime_str / try_set_mime_str companions returning Result.

pub fn maybe_with_content_size(self, size: Option<u64>) -> Part

Known content size in bytes. For streaming parts this allows the surrounding Form to advertise a Content-Length.

pub fn maybe_set_content_size(&mut self, size: Option<u64>) -> &mut Part

Known content size in bytes. For streaming parts this allows the surrounding Form to advertise a Content-Length.

pub fn with_content_size(self, size: u64) -> Part

Known content size in bytes. For streaming parts this allows the surrounding Form to advertise a Content-Length.

pub fn set_content_size(&mut self, size: u64) -> &mut Part

Known content size in bytes. For streaming parts this allows the surrounding Form to advertise a Content-Length.

pub fn without_content_size(self) -> Part

Known content size in bytes. For streaming parts this allows the surrounding Form to advertise a Content-Length.

pub fn unset_content_size(&mut self) -> &mut Part

Known content size in bytes. For streaming parts this allows the surrounding Form to advertise a Content-Length.

pub fn with_headers(self, headers: HeaderMap) -> Part

Replace the part’s headers (other than Content-Disposition and Content-Type, which are derived from the part’s metadata).

RFC 7578 §4.8 states that headers other than Content-Disposition, Content-Type, and (legacy) Content-Transfer-Encoding “MUST NOT be included and MUST be ignored” by receivers. Custom headers are allowed here for compatibility with non-standard receivers, but strictly conforming peers will silently drop them.

pub fn set_headers(&mut self, headers: HeaderMap) -> &mut Part

Replace the part’s headers (other than Content-Disposition and Content-Type, which are derived from the part’s metadata).

RFC 7578 §4.8 states that headers other than Content-Disposition, Content-Type, and (legacy) Content-Transfer-Encoding “MUST NOT be included and MUST be ignored” by receivers. Custom headers are allowed here for compatibility with non-standard receivers, but strictly conforming peers will silently drop them.

Trait Implementations

impl Debug for Part

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.