[ui/core] Add Validators paradigm

[nicolas-lambert-tc]

Description

Alicevision related PR

Add a standard way to validate the attribute value.
It add a way to apply validators to an attribute description and to represent in the UI when these attributes are not valid.

Validators

class AttributeValidator(object):

    def __call__(self, node: "Node", attribute: "Attribute") -> tuple[bool, list[str]]: raise NotImplementedError()


class NotEmptyValidator(AttributeValidator):

    def __call__(self, node: "Node", attribute: "Attribute") -> tuple[bool, list[str]]:

        if attribute.value is None or attribute.value == "":
            return error("Empty value are not allowed")
        
        return success()

Validators usage (can be a lambda)

desc.StringParam(
            name="input",
            label="Test input",
            description="",
            value="",
            validators=[
                NotEmptyValidator(),
                lambda node, attribute: success() if attribute == "test" else error("Attribute value should be 'test'")
                ]
        ),

Features list

• Add the notion of reusable validators
• Validator embed the error messages
• Validator can be a lambda
• An icon with error message appear when an attribute value is invalid (at least one validator return error messages)
• A node containing an invalid attribute is tagged with an orange icon and the selection rectangle is orange
• Attribute value is checked every time the attribute value is set (in the Command)
• A Warning Dialog is displayed before trying to submit a graph where a node is in warning state

[codecov]

Codecov Report

❌ Patch coverage is 92.98246% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.72%. Comparing base (e270ef5) to head (7a67e84).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
meshroom/core/attribute.py	81.25%	6 Missing ⚠️
meshroom/core/desc/attribute.py	93.33%	1 Missing ⚠️
meshroom/core/desc/validators.py	95.45%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3088      +/-   ##
===========================================
+ Coverage    83.56%   83.72%   +0.15%     
===========================================
  Files           81       83       +2     
  Lines        10322    10418      +96     
===========================================
+ Hits          8626     8722      +96     
  Misses        1696     1696              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Copilot]

Pull request overview

This PR introduces an attribute “validators” mechanism in meshroom.core and wires it through to the QML UI so invalid attributes and nodes can be visually flagged and warned about on submit.

Changes:

• Add reusable attribute validators (NotEmptyValidator, RangeValidator) and expose validation state/messages on runtime attributes/nodes.
• Update Graph Editor QML to display per-attribute and per-node warning indicators (orange styling + tooltip messages).
• Add tests and a test node description to exercise the new validation behavior.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
meshroom/core/desc/validators.py	Adds validator interfaces/helpers and two concrete validators.
meshroom/core/desc/attribute.py	Extends attribute description classes to accept validators=.
meshroom/core/attribute.py	Executes validators and exposes validation-related properties to the UI layer.
meshroom/core/node.py	Adds node-level hasInvalidAttribute property + change signal emission.
meshroom/ui/qml/GraphEditor/AttributeItemDelegate.qml	Adds per-attribute warning icon/border and tooltip changes.
meshroom/ui/qml/GraphEditor/Node.qml	Adds node-level warning icon and orange selection/border when warnings exist.
meshroom/ui/qml/Application.qml	Adds a warning dialog when submitting graphs containing nodes with warnings.
tests/nodes/test/nodeValidators.py	Adds a test node description that uses validators.
tests/test_attributes.py	Adds tests for NotEmpty and Range validation behavior.
meshroom/common/PySignal.py	Allows ClassSignal(...) to accept args/kwargs (for typed-signal parity).
meshroom/core/graph.py	Adds a new attributeValueChanged signal (currently only declared).
meshroom/ui/qml/Utils/format.js	Guards plainToHtml for falsy inputs.
meshroom/ui/qml/Utils/Colors.qml	Adds a warning color constant.
meshroom/ui/commands.py	Refactors attribute set to go through a single attribute reference.

Comments suppressed due to low confidence (1)

meshroom/core/desc/attribute.py:4

• types is imported but not used in this module. Please remove the unused import to keep the file clean (and to avoid failing lint checks if/when they are enabled).

import ast
import os
import re
from collections.abc import Iterable

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

name is declared twice on BaseNode (first as constant=True, then again later with notify=nodeNameChanged). The earlier declaration is redundant and can be misleading; please remove the duplicate name = Property(str, getName, constant=True) to keep a single source of truth for the Qt property.

[servantftransperfect]

I can't see a corresponding check on the new code ?

[servantftransperfect]

I can't see that signal emitted ?

[nicolas-lambert-tc]

It's needed because it's used internally by Qml. If not set, an error occure:
QQmlExpression: Expression file:///s/apps/users/lambertni/packages/meshroom/lambertni/repo/meshroom/ui/qml/GraphEditor/AttributeItemDelegate.qml:28:5 depends on non-NOTIFYable properties:

[servantftransperfect]

Shouldn't we have some caching here ? I guess getErrorMessages() is called many times, even if the attribute value did not change.

[nicolas-lambert-tc]

I tried to use caching, but I failed trying to keep the same robustness. Problems with connect/disconnect, undo/redo
It seems that signal have to be cared manually in a lot of places to be reactive on any user actions.
For now it's the more robust version i manage to have in a reasonable dev time.

[Alxiice]

If I read well validValue is not used anymore so is it possible to add a @deprecated.depreciateParam on it (like for the "group" attribute) and maybe check where it is used ?