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OpenAPI Generator API Reference

Generates C# extension methods and model classes from OpenAPI specifications.

Namespace: RestClient.Net.OpenApiGenerator

Overview

The OpenAPI Generator parses OpenAPI (Swagger) documents and generates strongly-typed C# code that integrates with RestClient.Net. It uses the Microsoft.OpenApi library for parsing.

OpenApiCodeGenerator

The main entry point for code generation from OpenAPI specifications.

Generate

Generates code from an OpenAPI document.

public static Result<GeneratorResult, string> Generate(
    string openApiContent,
    string @namespace,
    string className,
    string outputPath,
    string? baseUrlOverride = null,
    string jsonNamingPolicy = "camelCase",
    bool caseInsensitive = false
)

Parameters:

Returns: Result<GeneratorResult, string> - A Result containing either the generated code or an error message.

Example:

var openApiSpec = await File.ReadAllTextAsync("petstore.yaml");

var result = OpenApiCodeGenerator.Generate(
    openApiContent: openApiSpec,
    @namespace: "PetStore.Client",
    className: "PetStoreExtensions",
    outputPath: "./Generated",
    baseUrlOverride: "https://api.petstore.com",
    jsonNamingPolicy: "camelCase",
    caseInsensitive: true
);

result.Match(
    onSuccess: generated =>
    {
        Console.WriteLine("Extension methods generated!");
        Console.WriteLine(generated.ExtensionMethodsCode);
    },
    onError: error => Console.WriteLine($"Generation failed: {error}")
);

GeneratorResult

Represents the result of code generation.

public record GeneratorResult(
    string ExtensionMethodsCode,
    string ModelsCode
)

Properties:

ExtensionMethodGenerator

Generates C# extension methods from OpenAPI operations.

GenerateExtensionMethods

Generates extension methods from an OpenAPI document.

public static (string ExtensionMethods, string TypeAliases) GenerateExtensionMethods(
    OpenApiDocument document,
    string @namespace,
    string className,
    string baseUrl,
    string basePath,
    string jsonNamingPolicy,
    bool caseInsensitive
)

Parameters:

Returns: A tuple containing the extension methods code and type aliases code.

ModelGenerator

Generates C# model classes from OpenAPI schemas.

GenerateModels

Generates C# models from an OpenAPI document.

public static string GenerateModels(OpenApiDocument document, string @namespace)

Parameters:

Returns: string - The generated models code.

GenerateModel

Generates a single C# model record from an OpenAPI schema.

public static string GenerateModel(
    string name,
    OpenApiSchema schema,
    IDictionary<string, IOpenApiSchema>? schemas = null
)

Parameters:

Returns: string - The generated model code.

MapOpenApiType

Maps an OpenAPI schema to a C# type.

public static string MapOpenApiType(
    IOpenApiSchema schema,
    IDictionary<string, IOpenApiSchema>? schemas = null
)

Parameters:

Returns: string - The C# type name.

IsStringEnum

Checks if a schema is a string enum.

public static bool IsStringEnum(OpenApiSchema schema)

Parameters:

Returns: bool - True if the schema is a string enum.

SanitizeDescription

Sanitizes a description for use in XML comments.

public static string SanitizeDescription(string? description)

Parameters:

Returns: string - A single-line description safe for XML comments.

ParameterInfo

Parameter information for OpenAPI operations.

public record ParameterInfo(
    string Name,
    string Type,
    bool IsPath,
    bool IsHeader,
    string? OriginalName,
    bool Required,
    string? DefaultValue
)

Properties:

CodeGenerationHelpers

Helper methods for code generation.

ToPascalCase

Converts a string to PascalCase.

public static string ToPascalCase(string text)

Parameters:

Returns: string - The PascalCase version of the text.

ToCamelCase

Converts a string to camelCase.

public static string ToCamelCase(string text)

Parameters:

Returns: string - The camelCase version of the text.

Indent

Indents text by the specified number of levels.

public static string Indent(string text, int level)

Parameters:

Returns: string - The indented text.

BuildPathExpression

Builds a path expression from a path template.

public static string BuildPathExpression(string path)

Parameters:

Returns: string - The path expression.

SanitizePathParameters

Replaces path parameter names with their sanitized C# equivalents.

public static string SanitizePathParameters(string path, List<ParameterInfo> parameters)

Parameters:

Returns: string - The path with sanitized parameter names.

UrlParser

Parses base URLs and paths from OpenAPI documents.

GetBaseUrlAndPath

Gets the base URL and path from an OpenAPI document.

public static Result<(string BaseUrl, string BasePath), string> GetBaseUrlAndPath(
    OpenApiDocument document,
    string? baseUrlOverride = null
)

Parameters:

Returns: Result<(string BaseUrl, string BasePath), string> - A result containing the base URL and path, or an error message.

CLI Usage

The OpenAPI Generator is also available as a command-line tool:

restclient-openapi generate \
  --input petstore.yaml \
  --output ./Generated \
  --namespace PetStore.Client \
  --class PetStoreExtensions \
  --base-url https://api.petstore.com \
  --naming camelCase \
  --case-insensitive

See Also

• MCP Generator - Generate MCP servers from OpenAPI specs
• Getting Started with OpenAPI - Tutorial and examples