MVC / Razor Pages support for unions#67005
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Pull request overview
Adds functional coverage to ensure C# union types flow correctly through MVC’s System.Text.Json input/output formatters and through Razor Pages handler binding + JsonResult responses, complementing the existing Minimal API union coverage.
Changes:
- Adds a new
FormatterWebSitecontroller + model types to exercise union binding/serialization scenarios via MVC. - Adds MVC functional tests for union request-body binding (input formatter) and union return-type serialization (output formatter).
- Adds a Razor Pages smoke test site page + functional test to validate unions behave similarly in Razor Pages.
Show a summary per file
| File | Description |
|---|---|
| src/Mvc/test/WebSites/RazorPagesWebSite/Pages/Unions.cshtml.cs | Adds a Razor Page handler that returns and accepts a union via [FromBody]. |
| src/Mvc/test/WebSites/RazorPagesWebSite/Pages/Unions.cshtml | Adds the Razor Page endpoint for the unions smoke test. |
| src/Mvc/test/WebSites/FormatterWebSite/Models/UnionTypes.cs | Defines a set of union types (primitive/object/nested/classifier) used by MVC functional coverage. |
| src/Mvc/test/WebSites/FormatterWebSite/Controllers/UnionsController.cs | Adds MVC endpoints to serialize unions and echo unions back (input + output path). |
| src/Mvc/test/Mvc.FunctionalTests/SystemTextJsonOutputFormatterTest.Unions.cs | Adds output-formatter functional tests for union return types. |
| src/Mvc/test/Mvc.FunctionalTests/SystemTextJsonOutputFormatterTest.cs | Marks the test class partial to split union tests into a separate file. |
| src/Mvc/test/Mvc.FunctionalTests/SystemTextJsonInputFormatterTest.Unions.cs | Adds input-formatter functional tests for union request bodies (including ambiguous cases). |
| src/Mvc/test/Mvc.FunctionalTests/SystemTextJsonInputFormatterTest.cs | Marks the test class partial to split union tests into a separate file. |
| src/Mvc/test/Mvc.FunctionalTests/RazorPagesUnionsTest.cs | Adds functional tests validating union behavior through the Razor Pages pipeline. |
Copilot's findings
- Files reviewed: 9/9 changed files
- Comments generated: 1
Youssef1313
reviewed
Jun 3, 2026
| // [Theory] | ||
| // [InlineData("42", "42")] | ||
| // [InlineData("\"hi\"", "\"hi\"")] | ||
| // // TODO: enable null case after https://github.com/dotnet/runtime/issues/128688 is fixed. |
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Can we uncomment and skip the test instead ([Theory(Skip = "...")])?
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I'll uncomment this fully when #67024 merges, since it contains runtime fixes
Youssef1313
reviewed
Jun 3, 2026
| { | ||
| JsonTokenType.Number => typeof(int), | ||
| JsonTokenType.String => typeof(string), | ||
| JsonTokenType.Null => typeof(int), |
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Suggested change
| JsonTokenType.Null => typeof(int), | |
| JsonTokenType.Null => typeof(int?), |
| public override JsonTypeClassifier CreateJsonClassifier(JsonTypeClassifierContext context, JsonSerializerOptions options) => | ||
| static (ref Utf8JsonReader reader) => reader.TokenType switch | ||
| { | ||
| JsonTokenType.Number => typeof(int), |
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Suggested change
| JsonTokenType.Number => typeof(int), | |
| JsonTokenType.Number => typeof(int?), |
BrennanConroy
approved these changes
Jun 5, 2026
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nit: Change title, this is not adding support, it's adding tests
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#67024 merged |
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A follow-up of #66951 and #67001.
This PR adds tests to verify MVC and Razor Pages flow of union processing works, and different union usage cases are covered. MVC is a lower priority than Minimal API, but since the support is cheap, I am proposing to add coverage for MVC / Razor Pages as well.
Closes #66545