#multipart API reference

Build and parse multipart/form-data bodies (RFC 7578) - the file-upload counterpart to mime's email multipart. build assembles a list of Parts (form fields and files) into a (contentType, body) pair ready to POST; parse takes a Content-Type header and a body and returns the parts. Bodies are bytes, so binary file content round-trips intact.

Pairs with web / httpd for handling uploads and with http for sending them. Pure .j over strings + bytes; runs on both binaries.

Import with import "multipart.j" as multipart;. See the multipart guide for prose and examples.

#Functions

#multipart.build(parts as list of Part)

Build a form body with a fresh random boundary.

Parameters

• parts {list of Part} - the parts

Returns {Built} - the Content-Type and encoded body

#multipart.buildWith(parts as list of Part, boundary as string)

Build a form body with an explicit boundary (deterministic).

Parameters

• parts {list of Part} - the parts
• boundary {string} - the boundary token (must not occur in any part body)

Returns {Built} - the Content-Type and encoded body

#multipart.field(name as string, value as string)

A plain text form field.

Parameters

• name {string} - the field name
• value {string} - the field value

Returns {Part} - the part

#multipart.file(name as string, filename as string, contentType as string, data as bytes)

A file part.

Parameters

• name {string} - the field name
• filename {string} - the file name
• contentType {string} - the file's Content-Type (e.g. "text/plain")
• data {bytes} - the file content

Returns {Part} - the part

#multipart.isFile(p as Part)

Report whether a part is a file (has a filename).

Parameters

• p {Part} - the part

Returns {bool} - true if the part carries a filename

#multipart.parse(contentType as string, body as bytes)

Parse a multipart/form-data body into its parts.

Parameters

• contentType {string} - the Content-Type header (carrying the boundary)
• body {bytes} - the encoded body

Returns {list of Part} - the parts (fields and files)

Throws

• {Error} - kind "multipart" if the boundary is missing or a part is malformed

#multipart.text(p as Part)

Decode a part's body as a UTF-8 string (for reading text field values).

Parameters

• p {Part} - the part

Returns {string} - the decoded body

#Structs

#multipart.Built

A built form body plus the matching Content-Type header (with the boundary).

#multipart.Part

One form part: a field or a file.