setfn

func Middleware ¶

func Middleware[V any](key string, valueFn func() V) func(ctx *velaros.Context)

Middleware creates middleware that sets a dynamically-generated value on the message-level context. The valueFn function is called for each message to generate a fresh value. Values set at the message level only exist for the duration of that message's handler chain.

Use this when you need a unique value for each message (e.g., timestamps, UUIDs, request IDs).

Example:

router.Use(setfn.Middleware("requestID", func() string {
    return uuid.NewString()
}))

router.Bind("/data", func(ctx *velaros.Context) {
    requestID := ctx.MustGet("requestID").(string)  // Unique per message
    log.Printf("[%s] Processing request", requestID)
})

See also: set.Middleware for constant values, setvalue.Middleware for pointer values.