[dotnet] [bidi] Possibility to reset viewport

[nvborisenko]

User description

New pattern detected.

https://w3c.github.io/webdriver-bidi/#command-browsingContext-setViewport

browsingContext.SetViewportParameters = {
  ? context: browsingContext.BrowsingContext,
  ? viewport: browsingContext.Viewport / null,
  ? devicePixelRatio: float / null,
  ? userContexts: [+browser.UserContext],
}

Here viewport property is nullable. But if remote-end faces real null in json, then it behaves differently. So we just always send null if it is null.

🔧 Implementation Notes

Mark this special nullable with:

[property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]

🔄 Types of changes

• Cleanup (formatting, renaming)
• Bug fix (backwards compatible)

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PR Type

Bug fix, Enhancement

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Description

• Add JsonIgnore attribute to Viewport property for null serialization

• Enable viewport reset capability via BiDi setViewport command

• Ensure null viewport values are properly sent to remote endpoint

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Diagram Walkthrough

flowchart LR
  A["SetViewportParameters"] -->|"Add JsonIgnore attribute"| B["Viewport property"]
  B -->|"WhenWritingNull condition"| C["Null values serialized correctly"]
  C -->|"Enables"| D["Viewport reset capability"]

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File Walkthrough

Relevant files

Bug fix

SetViewportCommand.cs Add JsonIgnore attribute for null viewport serialization  dotnet/src/webdriver/BiDi/BrowsingContext/SetViewportCommand.cs Added System.Text.Json.Serialization using statement Applied [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] attribute to Viewport? property in SetViewportParameters record Enables proper serialization of null viewport values to reset viewport via BiDi protocol +2/-1

---

[qodo-merge-pro]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
🟢	No security concerns identified No security vulnerabilities detected by AI analysis. Human verification advised for critical code.
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: No auditing: The new serialization behavior for nullable viewport is not accompanied by any logging or audit trail, and it’s unclear whether this action is captured elsewhere. Referred Code using OpenQA.Selenium.BiDi.Communication; using System.Text.Json.Serialization; namespace OpenQA.Selenium.BiDi.BrowsingContext; internal sealed class SetViewportCommand(SetViewportParameters @params) : Command<SetViewportParameters, SetViewportResult>(@params, "browsingContext.setViewport"); internal sealed record SetViewportParameters(BrowsingContext Context, [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] Viewport? Viewport, double? DevicePixelRatio) : Parameters; public sealed class SetViewportOptions : CommandOptions { public Viewport? Viewport { get; set; } Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Null handling change: Changing to ignore null during serialization may mask intentional nulls versus omitted fields without explicit error handling or validation shown in this diff. Referred Code internal sealed record SetViewportParameters(BrowsingContext Context, [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] Viewport? Viewport, double? DevicePixelRatio) : Parameters; Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Input validation: The change adjusts serialization of nullable viewport but shows no validation for devicePixelRatio or viewport content, which may rely on upstream checks not visible here. Referred Code internal sealed record SetViewportParameters(BrowsingContext Context, [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] Viewport? Viewport, double? DevicePixelRatio) : Parameters; public sealed class SetViewportOptions : CommandOptions { public Viewport? Viewport { get; set; } Learn more about managing compliance generic rules or creating your own custom rules
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🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

[nvborisenko]

Nice catch, we already started doing it in another places. Let's find all occurences of this type (property: type / null) and mark all with this attribute.

[nvborisenko]

Ah, interesting: WhenWritingNull or WhenWritingDefault. We want to send json null obly if user explicitly wrote SomeNullableProperty = null.

[nvborisenko]

Verified, in both cases WhenWritingNull and WhenWritingDefault it doesn't serializes to json null.

await context.SetViewportAsync(new() { Viewport = null });
await context.SetViewportAsync();

    19:40:02.793 TRACE WebSocketTransport: BiDi SND --> {"id":3,"method":"browsingContext.setViewport","params":{"context":"D0E4F713FD009541B7FADB9D86BC5D6C"}}
19:40:02.795 TRACE WebSocketTransport: BiDi RCV <-- {"id":3,"result":{},"type":"success"}
19:40:02.796 TRACE WebSocketTransport: BiDi SND --> {"id":4,"method":"browsingContext.setViewport","params":{"context":"D0E4F713FD009541B7FADB9D86BC5D6C"}}
19:40:02.798 TRACE WebSocketTransport: BiDi RCV <-- {"id":4,"result":{},"type":"success"}

[nvborisenko]

LOL, we have used JsonIgnoreCondition.Never for these cases :D

[nvborisenko]

Yes, it always sends null:

19:46:18.576 TRACE WebSocketTransport: BiDi SND --> {"id":4,"method":"browsingContext.setViewport","params":{"context":"EAEFDFDBD3A2386DD196A128BE21FF1E","viewport":null}}

But I am more interesting whether it's possibly to send null only and only when user explicitly set it to null. Is it poossible?

[nvborisenko]

Bad news: if we send null then browser resets viewport, but user didn't want to do it.

So we really want to understand how to:

send null only and only when user explicitly set it to null

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	✅ Correct JSON serialization for optional parameters Suggestion Impact: The commit modified the JsonIgnore behavior on the Viewport property, changing its condition to Never to ensure null is serialized, addressing the core issue raised about Viewport. It did not move the attribute to DevicePixelRatio as suggested. code diff: -internal sealed record SetViewportParameters(BrowsingContext Context, [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] Viewport? Viewport, double? DevicePixelRatio) : Parameters; +internal sealed record SetViewportParameters(BrowsingContext Context, [property: JsonIgnore(Condition = JsonIgnoreCondition.Never)] Viewport? Viewport, double? DevicePixelRatio) : Parameters; To align with the WebDriver BiDi specification, correct the JSON serialization by removing the JsonIgnore attribute from the Viewport property and adding it to the DevicePixelRatio property. dotnet/src/webdriver/BiDi/BrowsingContext/SetViewportCommand.cs [28] -internal sealed record SetViewportParameters(BrowsingContext Context, [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] Viewport? Viewport, double? DevicePixelRatio) : Parameters; +internal sealed record SetViewportParameters(BrowsingContext Context, Viewport? Viewport, [property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)] double? DevicePixelRatio) : Parameters; [Suggestion processed] Suggestion importance[1-10]: 5 __ Why: The suggestion correctly identifies that the PR's change to Viewport is incorrect, as it prevents resetting the viewport by sending a null value. However, the proposed fix of moving the attribute to DevicePixelRatio is also incorrect, as the BiDi spec requires sending null to reset that value as well.	Low
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