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Fix null Content.Name binding errors - #5503
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Sébastien Duquette (sduquette-devolutions) wants to merge 1 commit into
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Sébastien Duquette (sduquette-devolutions) wants to merge 1 commit into
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The message "An error occurred binding 'Name' to 'Content.Name' at 'Content': 'Value is null.'" appeared multiple times in the console when starting the app. The cause was a global style in `Styles.Common.axaml`. It copies the automation name (the accessible name used by screen readers) from each `DataGridCell`'s content. The DataGrid reuses cells as you scroll, so the content is briefly null, and the old binding path then logged "Value is null." I replaced it with a binding that tolerates a null content. It uses a new converter, `Converters/AutomationNameOfContentConverter.cs`. The cell's accessible name is now read once from the content instead of tracking later changes to it. The templates set it statically, so that shouldn't matter in practice.
Sébastien Duquette (sduquette-devolutions)
requested review from
Gabriel Dufresne (GabrielDuf)
and
a balanced review from Copilot
October 10, 2026 13:23
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Sébastien Duquette (sduquette-devolutions)
October 10, 2026 13:24
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🟡 Changes recommended
The new binding can retain stale names and misses asynchronous automation-name updates.
2 open findings
What changed in this PR
Updates DataGrid automation-name binding to tolerate recycled cells with null content.
Changes:
- Adds an automation-name converter.
- Uses it in the global
DataGridCellstyle.
| File | Description |
|---|---|
AutomationNameOfContentConverter.cs |
Resolves automation names from cell content. |
Styles.Common.axaml |
Applies the converter globally to DataGrid cells. |
🧠 Review effort: Balanced
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| <Style Selector="DataGridCell"> | ||
| <Setter Property="automation:AutomationProperties.Name" Value="{Binding $self.((Control)Content).(automation:AutomationProperties.Name)}"/> | ||
| <Setter Property="automation:AutomationProperties.Name" Value="{Binding $self.Content, Converter={x:Static conv:AutomationNameOfContentConverter.Instance}}"/> |
| public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture) | ||
| => value is Control control | ||
| ? AutomationProperties.GetName(control) | ||
| : BindingOperations.DoNothing; |
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The message "An error occurred binding 'Name' to 'Content.Name' at 'Content': 'Value is null.'" appeared multiple times in the console when starting the app. The cause was a global style in
Styles.Common.axaml. It copies the automation name (the accessible name used by screen readers) from eachDataGridCell's content. The DataGrid reuses cells as you scroll, so the content is briefly null, and the old binding path then logged "Value is null."I replaced it with a binding that tolerates a null content. It uses a new converter,
Converters/AutomationNameOfContentConverter.cs. The cell's accessible name is now read once from the content instead of tracking later changes to it. The templates set it statically, so that shouldn't matter in practice.