Type Alias BeforeSendFn 

pub type BeforeSendFn = Box<dyn FnMut(Event) -> Option<Event> + Send + 'static>;

Hook that can modify or discard events before sending.

Each hook receives an owned Event and can:

• Return Some(event) to pass the (possibly modified) event to the next hook
• Return None to discard the event and stop further processing

Hooks are executed in order after the event is enriched with library/OS context. If any hook panics, the event is discarded and an error is logged.

Thread Safety

Hooks run in a background worker thread, so they must be Send + 'static. If you need randomness (e.g., for sampling), use a Send-compatible RNG like fastrand::Rng initialized before the closure.

Example

let options = better_posthog::ClientOptions {
  api_key: Some("phc_your_api_key".into()),
  before_send: vec![{
    // Initialize a scoped `Send`-compatible RNG.
    let mut rng = fastrand::Rng::new();

    // Return a `before_send` hook.
    Box::new(move |event| {
      let sample_rate = match event.event.as_str() {
        "button_click" => 0.5, // Process only a half of `button_click` events.
        _ => 1.0, // Process all other events.
      };
      if rng.f64() < sample_rate { Some(event) } else { None }
    })
  }],
  ..Default::default()
};

Aliased Type

pub struct BeforeSendFn(/* private fields */);