# `PhoenixKitBilling.Plugs.CacheBodyReader`
[🔗](https://github.com/BeamLabEU/phoenix_kit_billing/blob/0.5.1/lib/phoenix_kit_billing/plugs/cache_body_reader.ex#L1)

Body reader for `Plug.Parsers` that stashes the raw request body in
`conn.assigns.raw_body` so the webhook controller can verify provider
signatures.

Webhook signature verification (Stripe, PayPal, Razorpay) requires the
*exact* bytes the provider signed. `Plug.Parsers` consumes the request
body during JSON decoding, so the raw bytes are unavailable to
downstream plugs unless we capture them here.

## Host application setup

In your `Endpoint`, replace the default body reader on `Plug.Parsers`
with this module **only for the webhook path** to avoid keeping every
request body in memory:

    plug Plug.Parsers,
      parsers: [:urlencoded, :multipart, {:json, length: 10_000_000}],
      pass: ["*/*"],
      body_reader: {PhoenixKitBilling.Plugs.CacheBodyReader, :read_body, []},
      json_decoder: Phoenix.json_library()

The reader only caches the body when the request path matches
`/webhooks/billing/*`, so other requests behave normally.

## Why not a pipeline plug?

`Plug.Parsers` runs in the Endpoint, before router pipelines. Once the
body is parsed, the underlying socket is empty and a pipeline plug
cannot recover the raw bytes. The body reader is the only safe seam.

# `read_body`

Reads the request body, caches it in `conn.assigns.raw_body` for
webhook paths, and returns the standard `Plug.Conn.read_body/2` tuple.

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*Consult [api-reference.md](api-reference.md) for complete listing*