Middleware

Content Type

Reject request bodies in media types or encodings an endpoint doesn't accept.

Content Type turns away request bodies your endpoint can’t read, with 415 Unsupported Media Type, before a handler or binder sees them. Add it to JSON-only endpoints so a form post or an XML body fails with a clear status instead of a confusing binding error.

Usage

import "github.com/0mjs/zinc/middleware/contenttype"

app.Post("/events", contenttype.New(contenttype.Config{
  Types: []string{"application/json"},
}), createEvent) // createEvent: your handler

curl -i http://localhost:8080/events \
  -H "Content-Type: application/json" -d '{"name":"signup"}'
# HTTP/1.1 202 Accepted

curl -i http://localhost:8080/events \
  -H "Content-Type: text/plain" -d 'signup'
# HTTP/1.1 415 Unsupported Media Type
# Content-Type: application/json; charset=utf-8
#
# {"error":{"status":415,"message":"Unsupported Media Type"}}

Attach it to the routes that take a body. It checks every request it runs on, including a GET with no Content-Type (see Errors).

Defaults

Nothing is checked by default. An empty list allows anything, so you can check types without encodings, or the other way round.

Setting	Default
Media types	any
Content codings	any

Configuration

Accept JSON, sent either plain or gzip-compressed:

app.Post("/events", contenttype.New(contenttype.Config{
  Types:     []string{"application/json"},
  Encodings: []string{"identity", "gzip"},
}), createEvent)

curl -i http://localhost:8080/events \
  -H "Content-Type: application/json" -H "Content-Encoding: br" -d '{}'
# HTTP/1.1 415 Unsupported Media Type

Field	Default	Meaning
`Types`	any	Accepted media types. Parameters and case are ignored, so `application/json; charset=utf-8` matches `application/json`.
`Encodings`	any	Accepted content codings, such as `gzip`. A request without `Content-Encoding` counts as `identity`, so list `identity` to allow plain bodies.

contenttype only checks the header. To accept gzip bodies, add Decompress as well.

Errors

A request that fails either check gets 415 Unsupported Media Type (zinc.ErrUnsupportedMediaType), and the handler doesn’t run.

Decompress: accepts gzip request bodies.
Body Limit: caps the size of request bodies.
Binding: reads the body into a struct once it’s accepted.