Add JsonIgnore attribute support to Minimal API validation generator

[Copilot]

This PR fixes an issue where Minimal API validation would throw a "Maximum validation depth exceeded" exception when processing types like JsonPatchDocument that contain properties with circular references marked with [JsonIgnore] attributes.

Problem

When using the new JsonPatchDocument<T> for System.Text.Json in .NET 10 with Minimal API validation enabled, the validation generator would traverse all properties of the type, including those marked with [JsonIgnore]. This caused infinite recursion through circular references in properties like SerializerOptions.Default.Default..., leading to:

System.InvalidOperationException: Maximum validation depth of 32 exceeded at 'SerializerOptions.Default.Default.Default...' in 'JsonSerializerOptions'. This is likely caused by a circular reference in the object graph.

Solution

The fix adds support for recognizing and skipping properties and parameters marked with [JsonIgnore] attributes during validation type discovery, similar to how [FromServices] attributes are already handled.

Key changes:

• Added System.Text.Json.Serialization.JsonIgnoreAttribute to well-known types
• Created IsJsonIgnoredProperty and IsJsonIgnoredParameter extension methods
• Updated ExtractValidatableMembers to skip properties/parameters with [JsonIgnore] attributes
• Added comprehensive test coverage for the JsonIgnore functionality

Example

With this fix, the following endpoint will work correctly:

app.MapPatch("/items/{id}", (int id, JsonPatchDocument<Item> patchDoc) => 
{
    // Validation will only process non-JsonIgnore properties
    return Results.Ok();
});

The validation generator will now properly exclude properties marked with [JsonIgnore] from validation traversal, preventing circular reference exceptions while still validating all other properties with validation attributes.

Fixes #63047.

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[captainsafia]

@copilot Update the CanValidateComplexTypesWithJsonIgnore test with cases to cover record types. Use the existing test method and don't create a new one.

[Copilot]

@copilot Update the CanValidateComplexTypesWithJsonIgnore test with cases to cover record types. Use the existing test method and don't create a new one.

Updated the CanValidateComplexTypesWithJsonIgnore test with record type test cases. Added RecordTypeWithJsonIgnore and CircularReferenceRecord types along with corresponding test validation for both the record endpoint and the existing class endpoint. The test now covers JsonIgnore functionality for both classes and records within the same test method as requested.

Commit: d038ce7

[captainsafia]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[Copilot]

Pull Request Overview

This PR adds support for respecting [JsonIgnore] attributes in the Minimal API validation generator to prevent "Maximum validation depth exceeded" exceptions when processing types with circular references. The primary purpose is to exclude properties marked with [JsonIgnore] from validation traversal, similar to how [FromServices] attributes are already handled.

Key changes:

• Added JsonIgnoreAttribute to well-known types and created helper methods to detect it
• Updated validation member extraction logic to skip properties with [JsonIgnore] attributes
• Added comprehensive test coverage for both class and record types with JsonIgnore functionality

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
WellKnownTypeData.cs	Added System_Text_Json_Serialization_JsonIgnoreAttribute to well-known types
RequiredSymbols.cs	Added JsonIgnoreAttribute symbol to required symbols record
ITypeSymbolExtensions.cs	Added IsJsonIgnoredProperty extension method for detecting JsonIgnore attributes
ValidationsGenerator.TypesParser.cs	Updated member extraction logic to skip JsonIgnore properties
ValidationsGenerator.ComplexType.cs	Added comprehensive test coverage for JsonIgnore functionality
ValidatableInfoResolver.g.verified.cs	Generated test snapshot showing correct exclusion of JsonIgnore properties

[Copilot]

Consider adding a null check for jsonIgnoreAttributeSymbol before calling the extension method to handle cases where the symbol might not be available.

[Copilot]

Consider adding a null check for jsonIgnoreAttributeSymbol before calling the extension method to handle cases where the symbol might not be available.

[BrennanConroy]

Philosophically, do we want this change? We're slowly adding more Json specific features to the general purpose validation feature.

We also just added [SkipValidation] which is what should be used if you don't want something to be validated.

[BrennanConroy]

Not relevant for this change, but does this comparison work for derived types?
e.g. MyFromKeyedServicesAttribute : FromKeyedServicesAttribute

See code a few lines above

[captainsafia]

It won't, but JsonIgnoreAttribute is sealed so there's not likely to be derived types. FromKeyedServices is not.

[BrennanConroy]

So we should update the keyed service check in a separate PR

[captainsafia]

Yep -- we want to probably do an audit across the repo for anywhere we type check on FromKeyedServices and FromServices since both of those are unsealed.

[captainsafia]

Philosophically, do we want this change? We're slowly adding more Json specific features to the general purpose validation feature.

The ship has sailed a bit on the source generator not having any STJ-specific logic in the generator since it already has logic for walking [JsonDerived] types as part of the discovery (ref).

I know we were hard core about the philosophical distinction for the property naming policy but this one feels more necessary since being incompatible with the serialziation rules by default could mean that we validate properties that are never serialized/set.