Response Middleware

The maniflex/middleware/response package shapes the outgoing response — headers, body transforms, redactions, and observability hooks — on the Response step.

Cross-cutting headers

`CORSHeaders`

Adds CORS headers to every response. Reasonable defaults; pass options to restrict origins, methods, or credentials.

import "github.com/xaleel/maniflex/middleware/response"

server.Pipeline.Response.Register(response.CORSHeaders())

`AddHeader`

Sets one static header on every response:

server.Pipeline.Response.Register(
    response.AddHeader("Strict-Transport-Security", "max-age=63072000"),
)

Caching

`Cache`

Sets Cache-Control: public, max-age=N on successful reads. Register at maniflex.After so the framework’s own headers do not override yours:

server.Pipeline.Response.Register(
    response.Cache(300),  // 5 minutes
    maniflex.ForOperation(maniflex.OpRead, maniflex.OpList),
    maniflex.AtPosition(maniflex.After),
)

Body transforms

`TransformField`

Rewrites a single field value before serialisation. Common use: rebasing a stored relative path onto a CDN host.

server.Pipeline.Response.Register(
    response.TransformField("avatar_url", func(v any) any {
        return cdnBase + v.(string)
    }),
)

`RedactField`

Hides a field from the response conditionally. The predicate decides per request, often based on ctx.Auth:

server.Pipeline.Response.Register(
    response.RedactField("phone", func(ctx *maniflex.ServerContext) bool {
        return !ctx.HasRole("support")
    }),
)

RedactField is the right tool for view-time access control on individual columns. For all-or-nothing exclusion across an entire model, the hidden or writeonly field tag is simpler.

`Envelope`

Replaces the default {"data": ...} envelope with one of your own:

server.Pipeline.Response.Register(
    response.Envelope(func(ctx *maniflex.ServerContext, data any, meta *maniflex.ResponseMeta) any {
        return map[string]any{
            "result":   data,
            "paging":   meta,
            "trace_id": ctx.TraceID,
        }
    }),
)

Useful when integrating with a frontend or API gateway that expects a different shape. Error responses are unaffected; only success responses are re-enveloped.

Observability

`Logging`

Writes a structured access log line per request at maniflex.After:

server.Pipeline.Response.Register(
    response.Logging(slog.Default()),
    maniflex.AtPosition(maniflex.After),
)

The line carries request ID, trace ID, method, path, status, duration, and the authenticated user when set.

`Metrics`

Records per-request metrics — count, latency, status class — into a configured collector:

server.Pipeline.Response.Register(
    response.Metrics(myCollector),
    maniflex.AtPosition(maniflex.After),
)

A reference Prometheus collector is provided; any sink with the same interface works.

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