1193 multipage validation #1201
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looks like dropdown is generating warnings from React ATM
| @@ -730,11 +730,7 @@ def multipage_app(validation=False): | |||
| layout_page_2 = html.Div( | |||
| [ | |||
| html.H2("Page 2"), | |||
| dcc.Dropdown( | |||
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dcc.Dropdown is giving React deprecated lifecycle method warnings ATM... I thought we had already updated all of these in the 16.13 push? Anyway switched to Input to get my assert not dash_duo.get_logs() clean console test to pass.
dash/dash.py
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| _validate.validate_layout(value, layout_value) | ||
| self.validation_layout = simple_clone( | ||
| # pylint: disable=protected-access | ||
| layout_value, [simple_clone(c) for c in layout_value._traverse_ids()] |
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Make this validation layout as simple as possible, to minimize its overhead on the page:
- strip out components with no ID
- strip out most prop values, at least in Py3 where we can fully inspect the component constructor signature so we know what props are required.
This step is only run once when you set the layout, and even then only when you set it to a function AND you haven't already set app.validation_layout
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If we're just using this to validate IDs w.r.t. callbacks, why do we need the required values?
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We also validate props against the component type, so we can't just create dummy components, they have to be the same type as the real components. And unless I were to recreate the JSON serialization for components, the easiest way to do that is to actually instantiate the same component class. But doing so requires that we include required props, because the generated components enforce the required props during construction.
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Ohhhhhh by "props against the component type" do you mean during callback validation with messages like e.g. "You registered a callback to update a Div's childrenz property. However, Div does not have a "children" property."?
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e.g. "You registered a callback to update a Div's childrenz property. However, Div does not have a "childrenz" property."?
exactly.
| const validateIds = !config.suppress_callback_exceptions; | ||
| let layout, paths; | ||
| if (validateIds && config.validation_layout) { | ||
| layout = config.validation_layout; |
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Is this because validation_layout is pruned down, so faster to crawl?
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This is just saying if we have a separate validation layout, that's the one we need to check the callbacks against. The fact that it's pruned should make computePaths (next line) faster, but the main reason for pruning was to reduce the size of _dash-config on the index page - I was imagining it could become enormous, if you have multiple tables and graphs on different pages all concatenated together.
dash/dash.py
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| self._layout = value | ||
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| # for using flask.has_request_context() to deliver a full layout for | ||
| # validation inside a layout function - track if a user might be doing this. | ||
| if self._layout_is_function and not self.validation_layout: |
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I wonder if this is something we should turn off if debug=False too, or introduce a new dev_tools_validate_layout function. Just to reduce the performance hit if there are many small components (e.g. a dash_html_components.Table)
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Good point. Those mostly wouldn't have IDs, so wouldn't be sent to the front end anyway, but with debug off we don't need it at all. In fact I guess we should be able to short-circuit all the front-end validation in that case too.
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I added clauses to skip this when suppress_callback_validation is used, but didn't remove it entirely when debug=False. There's more to think about here - on the one hand, without this validation the app behavior can change, and on the other there's a lot more validation we could be skipping if that's what we want to do. I've created #1206 to follow up.
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I confirm the fix works on my app (tested with |
Fixes #1193 - the
flask.has_request_contexttrick inside anapp.layoutfunction can be used again to supply a special layout just for validation purposes.In addition, added a new attribute
app.validation_layoutthat does the same thing more explicitly.Contributor Checklist
CHANGELOG.md