[Feat] Hide all Vizro internal callbacks

[antonymilne]

Description

FYI @noklam

Dash 3.3.0 and 3.4.0 introduce a hidden argument to hide callbacks from the dev tools graph. I've marked all our Vizro callbacks as hidden so that only the "core" action callbacks remain.

For some debugging purposes this might be a bit too aggressive and hiding too much, but I think that's only relevant for Vizro developers rather than users. So then we can temporarily remove the hidden=True as and when needed during development.

There's a couple of issues with the new Dash features that I've raised on their repo:
[BUG] hide_all_callbacks doesn't apply to clientside callbacks - this means it's not possible for us to use this argument, so we just manually mark all relevant callbacks as hidden=True (which is probably the best approach for us anyway)
[BUG] Dash pages callback not fully hidden - just a small problem but would be nice to fix @l0uden

Screenshot

The callback graph is still massively overwhelming in a big app, so it's best just to comment out all pages but one if you actually want to use this graph.

Example 1: one page on export data action in hatch run example:dev.

Before this PR:

After this PR

Example 2: chained actions taken from custom actions tutorial

Before this PR

After this PR

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[github-actions]

View the example dashboards of the current commit live on PyCafe ☕ 🚀

Updated on: 2026-01-22 11:13:41 UTC
Commit: ac0ad45

Compare the examples using the commit's wheel file vs the latest released version:

vizro-core/examples/scratch_dev

View with commit's wheel vs View with latest release

vizro-core/examples/dev/

View with commit's wheel vs View with latest release

vizro-core/examples/visual-vocabulary/

View with commit's wheel vs View with latest release

vizro-core/examples/tutorial/

View with commit's wheel vs View with latest release

[petar-qb]

Thanks @antonymilne for introducing this improvement and for creating new dash issues! 🙌

I want to raise further questions/ideas around callback visibility.

Should we consider enabling visibility of all callbacks in Vizro when the dashboard creator explicitly opts in like Vizro(hide_all_callbacks=False).build(dashboard).run() (by default it's True)? It's maybe an overkill to propagate this flag to all clientside callback you hide like hidden=hide_all_callbacks

Ideally, the default behaviour could be to show only the callbacks relevant to the currently opened page. I realise this is non-trivial to implement on the Dash side as an option, but it would be a great UX improvement.

Related to that, it would be useful if certain DashDependency objects could be hidden from the callback graph entirely. For example: Output(f"{id}_finished", "data", hidden=True). Other candidates would be "_guarded_trigger" and "action_progress_indication_placeholder".

These changes would allow us to exclude all our internal dependencies and keep the graph focused on what actually matters to the dashboard creator.

[l0uden]

Here's the PR that fixes problems form description

[antonymilne]

Thanks for the quick review guys!

@petar-qb

Should we consider enabling visibility of all callbacks in Vizro when the dashboard creator explicitly opts in like Vizro(hide_all_callbacks=False).build(dashboard).run() (by default it's True)? It's maybe an overkill to propagate this flag to all clientside callback you hide like hidden=hide_all_callbacks

Yes, potentially we could do that in future. It might be useful to make it more fine-grained like a kind of logging level/verbosity:

• level = 0: show only explicitly defined actions (like now)
• level = 1: level 0 + show callbacks used in actions (like guard trigger)
• level = 2: show all callbacks

Or something like that anyway.

@noklam already asked out of curiosity whether there was a way to turn back on the vizro callbacks but didn't have a use for it yet. So let's wait until someone would actually find it useful to understand what callbacks they would like to see.

There's also a question about where this argument would go exactly. Dash's hide_all_callbacks is in run rather than Vizro. We could potentially also do it with an environment variable.

Ideally, the default behaviour could be to show only the callbacks relevant to the currently opened page. I realise this is non-trivial to implement on the Dash side as an option, but it would be a great UX improvement.

Agreed, this would be a huge improvement. Maybe worth making a feature request on Dash? I have no idea off the top of my head how it would work or if it's even possible. But realistically in any slightly complex multi-page app at the moment the callback graph is pretty unusable.

Related to that, it would be useful if certain DashDependency objects could be hidden from the callback graph entirely. For example: Output(f"{id}_finished", "data", hidden=True). Other candidates would be "_guarded_trigger" and "action_progress_indication_placeholder".

These changes would allow us to exclude all our internal dependencies and keep the graph focused on what actually matters to the dashboard creator.

Yes agreed, I wanted to do exactly this but couldn't. The graph would need to resolve some scenarios for chained callbacks like what happens if Output(hidden=True) is the Input(hidden=False) to another callback, but I don't think it would too hard to resolve to something sensible. Maybe also worth another feature request on Dash? 🤔 I don't think these would be high priority for them but are potentially something @l0uden could contribute with his new Dash expertise 😀

[petar-qb]

Here are the feature requests:

• [Feature Request] Dev Tools Callback Graph per Page
• [Feature Request] Dev Tools Callback Graph - Allow hiding specific DashDependency objects

[petar-qb]

Hey @antonymilne, would you mind adding the black>=26.0.0 constraint? I missed it in https://github.com/mckinsey/vizro/pull/1545/changes. Thanks!

[antonymilne]

Hey @antonymilne, would you mind adding the black>=26.0.0 constraint? I missed it in https://github.com/mckinsey/vizro/pull/1545/changes. Thanks!

Oops sorry, I missed this... But actually I don't think it's worth doing because it's not really a requirement for users, just for our tests to pass. If our tests break again then we can pin it in the test environment but if not then I think let's just leave it as is.