Correcting and clarifying RegularExpressionAttribute.IsValid

[daiplusplus]

Summary

• RegularExpressionValidator.IsValid does not throw ValidationException
• Adding remark that Object? values are converted to a String using Convert.ToString which I found a tad surprising (as instead I expected it to throw if a non-null, non-string argument was passed).
• Adding remark about how null and empty strings are considered valid.

Fixes #8164

[ghost]

Tagging subscribers to this area: @dotnet/area-system-text-regularexpressions
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Issue Details

---

Summary

• RegularExpressionValidator.IsValid does not throw ValidationException
• Adding remark that Object? values are converted to a String using Convert.ToString which I found a tad surprising (as instead I expected it to throw if a non-null, non-string argument was passed).
• Adding remark about how null and empty strings are considered valid.

Fixes #8164

Author:	Jehoel
Assignees:	-
Labels:	area-System.Text.RegularExpressions
Milestone:	-

[opbld30]

Docs Build status updates of commit 161a4da:

⚠️ Validation status: warnings

File	Status	Preview URL	Details
xml/System.ComponentModel.DataAnnotations/RegularExpressionAttribute.xml	⚠️Warning	View	Details

xml/System.ComponentModel.DataAnnotations/RegularExpressionAttribute.xml

• Line 0, Column 0: [Warning: xref-not-found] Cross reference not found: 'System.Convert.ToString(object?,IFormatProvider?)'.

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[opbld31]

Docs Build status updates of commit 04da9eb:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.ComponentModel.DataAnnotations/RegularExpressionAttribute.xml	✅Succeeded	View

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

For any questions, please:

• Try searching the docs.microsoft.com contributor guides
• Post your question in the Docs support channel

[ghost]

Tagging subscribers to this area: @ajcvickers
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Summary

• RegularExpressionValidator.IsValid does not throw ValidationException
• Adding remark that Object? values are converted to a String using Convert.ToString which I found a tad surprising (as instead I expected it to throw if a non-null, non-string argument was passed).
• Adding remark about how null and empty strings are considered valid.

Fixes #8164

Author:	Jehoel
Assignees:	-
Labels:	area-System.ComponentModel.DataAnnotations
Milestone:	-