Module body_transformer 

The body-transformer node — rewrites the request and/or response body from a template.

Deviation from APISIX (read this first)

APISIX’s body-transformer renders full lua-resty-template templates (arbitrary Lua expressions, loops, helpers) over bodies decoded from xml, json, encoded, args, plain, or multipart input. featherbit implements a deliberate subset:

• input_format supports json only (other formats are rejected at config load; omitting it defaults to json).

• Templates are plain strings with two placeholder forms:

  • {{body.x.y}} — a dotted path resolved from the parsed JSON body (numeric segments index arrays; {{body}} is the whole document). Strings are inserted raw (unquoted), numbers/bools verbatim, missing values and null as the empty string, and objects/arrays as compact JSON.
  • {{$var}} — a context variable via crate::vars::resolve ($uri, $http_x_id, $arg_page, …).

  Text outside {{ }} additionally passes through crate::vars::interpolate, so bare $var references work there too.

• template_is_base64 is not supported (templates are stored literally in YAML) and is rejected at config load.

Structs

BodyTransformerPlugin

Rewrites context.request.body and/or context.response.body by rendering a template against the parsed JSON body and context variables.

Functions

json_path 🔒

Resolves a dotted path (x.y.0) inside a JSON value; an empty path returns the value itself.

json_to_template_string 🔒

Stringifies a resolved JSON value for template insertion: strings raw, scalars verbatim, null empty, containers as compact JSON.

parse_body 🔒

Parses a body as JSON; empty bodies become null so templates still render (with empty {{body...}} placeholders).

parse_transform 🔒

Validates one request/response transform object and returns its template string.

render 🔒

Renders a template: {{body.path}} from the parsed body, {{$var}} via crate::vars::resolve, and $var interpolation on the literal text between placeholders. Unknown placeholders resolve to the empty string; values substituted from the body are not re-interpolated.