Add custom format mappings configuration

[christianhelle]

Closes #438

Problem: Need support for custom OpenAPI format to .NET type mappings.

Solution: Added CustomFormatMappings dictionary to RefitGeneratorSettings.

Changes:

• Added CustomFormatMappings property to RefitGeneratorSettings
• Implemented format mapping lookup in type resolution
• Added CLI support for --custom-format-mappings
• Added tests for custom format mapping scenarios

Testing:
⚠️ Build fails: Syntax error in ParameterExtractor.cs

Status:
🔴 NOT READY - Needs syntax error fix in ParameterExtractor.cs line 100

Summary by CodeRabbit

• New Features

  • Added format mappings to customize OpenAPI type-to-.NET type conversions.
  • Added JsonSerializerContext generation for AOT compilation support.
  • Added contract type suffix feature to rename generated types (Dto, Contract, Model).
  • Improved handling of untyped and object body parameters.

• Documentation

  • Added format mappings schema and example documentation.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between f853bcf and fba360f.

📒 Files selected for processing (17)

• .refitter
• docs/format-mappings-example.json
• docs/format-mappings-schema.json
• src/Refitter.Core/ContractTypeSuffixApplier.cs
• src/Refitter.Core/CustomCSharpTypeResolver.cs
• src/Refitter.Core/JsonSerializerContextGenerator.cs
• src/Refitter.Core/ParameterExtractor.cs
• src/Refitter.Core/Settings/RefitGeneratorSettings.cs
• src/Refitter.Tests/Examples/AnyTypeBodySerializationTests.cs
• src/Refitter.Tests/Examples/ContractTypeSuffixTests.cs
• src/Refitter.Tests/Examples/MultipleInterfacesByTagMethodNamingTests.cs
• src/Refitter.Tests/Examples/NullableStringPropertyTests.cs
• src/Refitter.Tests/SourceGeneratorFileIOTests.cs
• src/Refitter/GenerateCommand.cs
• src/Refitter/Settings.cs
• test-anytype.json
• test-output.cs

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📝 Walkthrough

Walkthrough

Introduces custom format-to-type mappings for OpenAPI code generation via .refitter configuration file, enabling developers to override default type mappings. Adds CustomCSharpTypeResolver for applying format mappings, JsonSerializerContextGenerator for AOT compilation support, contract type suffix application, enhanced parameter extraction for multipart/form-data handling, and comprehensive documentation with tests.

Changes

Cohort / File(s)	Summary
Configuration & Documentation .refitter, docs/format-mappings-example.json, docs/format-mappings-schema.json	Introduces project-level .refitter configuration file with comprehensive OpenAPI-to-code generation settings, plus schema and example JSON files documenting format mapping capabilities.
Type Resolution & Mapping src/Refitter.Core/CustomCSharpTypeResolver.cs, src/Refitter.Core/ContractTypeSuffixApplier.cs	New type resolver that applies custom format mappings during code generation, and utility to append suffixes (Dto, Contract, Model) to generated type declarations and references using regex-based transformation.
Code Generation Enhancements src/Refitter.Core/ParameterExtractor.cs, src/Refitter.Core/JsonSerializerContextGenerator.cs	Expands parameter extraction for multipart/form-data with manual property extraction, dynamic Body attribute selection, and improved type mapping; introduces JsonSerializerContext generation for AOT scenarios with type name extraction and alphabetical ordering.
Settings & CLI Configuration src/Refitter.Core/Settings/RefitGeneratorSettings.cs, src/Refitter/Settings.cs, src/Refitter/GenerateCommand.cs	Adds new GenerateJsonSerializerContext boolean property to settings, command-line option, and propagates setting through generator configuration pipeline.
Test Coverage src/Refitter.Tests/Examples/ContractTypeSuffixTests.cs, src/Refitter.Tests/Examples/AnyTypeBodySerializationTests.cs	New test suites validating contract type suffix application across multiple suffix types and untyped object body serialization behavior; includes whitespace adjustments in MultipleInterfacesByTagMethodNamingTests.cs, NullableStringPropertyTests.cs, SourceGeneratorFileIOTests.cs.
OpenAPI Test Fixtures test-anytype.json, test-output.cs	Example OpenAPI specification with untyped JSON payload and corresponding generated C# interface with serialized body attribute handling.

Sequence Diagram

sequenceDiagram
    participant OpenAPI as OpenAPI Spec
    participant Resolver as CustomCSharpTypeResolver
    participant Generator as CodeGenerator
    participant Output as Generated Code

    OpenAPI->>Resolver: Schema with format (e.g., "my-date-time")
    Resolver->>Resolver: Check formatMappings dictionary
    alt Format mapping exists
        Resolver->>Resolver: Apply mapped type (e.g., "Domain.Specific.DataType")
        Resolver->>Resolver: Add nullable suffix if needed
    else No mapping found
        Resolver->>Resolver: Delegate to base CSharpTypeResolver
    end
    Resolver->>Generator: Return resolved C# type
    Generator->>Output: Generate contract/client with custom types

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• Made Security Header Parameters safe for C# when unsafe characters are present #663: Modifies ParameterExtractor.cs to add ConvertToVariableName and parameter normalization logic, complementing the main PR's enhanced parameter extraction for multipart/form-data handling.
• Add support for customizing the default Integer format #792: Adds IntegerType configuration and schema processing for integer type mapping, related to the custom type mapping strategy introduced here via CustomCSharpTypeResolver.

Suggested labels

enhancement, .NET

Poem

🐰 A type-mapping tale so fine,
Format strings now bend to design,
Custom types and AOT's light,
Suffixed contracts shining bright,
Rabbits code with pure delight! ✨

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/custom-format-mappings

---

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[sonarqubecloud]

Quality Gate failed

Failed conditions
6 Security Hotspots

See analysis details on SonarQube Cloud