fix: pass before_send through module-level setup

[sipa-echo-zaoa]

Summary

• pass the module-level posthog.before_send callback into the lazily initialized default client
• add a regression test covering module-level initialization so posthog.capture(...) uses the callback
• unblock Django apps that rely on global setup to suppress unwanted exception events like Http404 via before_send

Closes #450

[greptile-apps]

Comments Outside Diff (1)

1. posthog/__init__.py, line 881-883 (link)

   before_send not re-applied to an already-initialized client

   disabled and debug are always re-applied to the existing default_client on every setup() call so that users can change them after the first capture. before_send is not given the same treatment — it is only forwarded during initial construction.

   This means the following sequence silently ignores the callback:

   posthog.api_key = "phc_..."
   posthog.capture("first_event")   # client is constructed here, before_send is None
   posthog.before_send = my_callback
   posthog.capture("second_event")  # callback is NOT invoked

   This doesn't affect the bug being fixed (callback set before the first call), but it is an inconsistency with how disabled/debug behave. Consider adding default_client.before_send = before_send alongside the other post-init updates, or at minimum documenting that before_send must be configured before the first SDK call.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: posthog/__init__.py
   Line: 881-883
   
   Comment:
   **`before_send` not re-applied to an already-initialized client**
   
   `disabled` and `debug` are always re-applied to the existing `default_client` on every `setup()` call so that users can change them after the first capture. `before_send` is not given the same treatment — it is only forwarded during initial construction.
   
   This means the following sequence silently ignores the callback:
   
   ```python
   posthog.api_key = "phc_..."
   posthog.capture("first_event")   # client is constructed here, before_send is None
   posthog.before_send = my_callback
   posthog.capture("second_event")  # callback is NOT invoked
   ```
   
   This doesn't affect the bug being fixed (callback set *before* the first call), but it is an inconsistency with how `disabled`/`debug` behave. Consider adding `default_client.before_send = before_send` alongside the other post-init updates, or at minimum documenting that `before_send` must be configured before the first SDK call.
   
   How can I resolve this? If you propose a fix, please make it concise.

Prompt To Fix All With AI

This is a comment left during a code review.
Path: posthog/__init__.py
Line: 881-883

Comment:
**`before_send` not re-applied to an already-initialized client**

`disabled` and `debug` are always re-applied to the existing `default_client` on every `setup()` call so that users can change them after the first capture. `before_send` is not given the same treatment — it is only forwarded during initial construction.

This means the following sequence silently ignores the callback:

```python
posthog.api_key = "phc_..."
posthog.capture("first_event")   # client is constructed here, before_send is None
posthog.before_send = my_callback
posthog.capture("second_event")  # callback is NOT invoked
```

This doesn't affect the bug being fixed (callback set *before* the first call), but it is an inconsistency with how `disabled`/`debug` behave. Consider adding `default_client.before_send = before_send` alongside the other post-init updates, or at minimum documenting that `before_send` must be configured before the first SDK call.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "fix: pass before_send through module-lev..." | Re-trigger Greptile}

[sipa-echo-zaoa]

Hi @marandaneto,
Could you please take a look at this PR?

Thanks.

[marandaneto]

@sipa-echo-zaoa you need to force push your changes with signed commits otherwise we cannot merge this in

[marandaneto]

also format your code with ruff

[sipa-echo-zaoa]

@marandaneto I've rebased formatted and force pushed.