Rivet.Attributes 0.28.0

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End-to-end type safety between .NET and TypeScript. No drift, no schema files, no codegen config.

If .NET can express a type that can be serialised on the wire, Rivet can make it TypeScript on the other side. It maps exactly what can survive a JSON boundary — no more, no less.

oRPC gives you this when your server is TypeScript. Rivet gives you the same DX when your server is .NET.

New here? Follow the Tutorial: Zero to Typed Client — dotnet new webapi to a fully typed TS client in under 5 minutes.

Install

dotnet add package Rivet.Attributes --version "*"
dotnet tool install --global dotnet-rivet

Mark your C# types → get TypeScript types

[RivetType]
public enum Priority { Low, Medium, High, Critical }

[RivetType]
public sealed record Email(string Value); // single-property → branded

[RivetType]
public sealed record TaskItem(Guid Id, string Title, Priority Priority, Email Author);

[RivetType]
public sealed record ErrorDto(string Code, string Message);

// Generated
export type Priority = "Low" | "Medium" | "High" | "Critical";
export type Email = string & { readonly __brand: "Email" };
export type TaskItem = { id: string; title: string; priority: Priority; author: Email };
export type ErrorDto = { code: string; message: string };

Mark your controllers → get a typed client

[RivetClient]
[Route("api/tasks")]
public sealed class TasksController : ControllerBase
{
    [HttpGet("{id:guid}")]
    [ProducesResponseType(typeof(ErrorDto), 404)]
    public async Task<ActionResult<TaskDetailDto>> Get(Guid id, CancellationToken ct) { ... }
}

// Generated — discriminated union, narrowable by status
export type GetResult =
  | { status: 200; data: TaskDetailDto; response: Response }
  | { status: 404; data: ErrorDto; response: Response }
  | { status: Exclude<number, 200 | 404>; data: unknown; response: Response };

const task = await tasks.get(id);                        // → TaskDetailDto (throws on error)
const result = await tasks.get(id, { unwrap: false });   // → GetResult (no throw)

Or define contracts → get compile-time enforcement

// Define the API surface — pure Rivet, no ASP.NET dependency
[RivetContract]
public static class MembersContract
{
    public static readonly RouteDefinition<List<MemberDto>> List =
        Define.Get<List<MemberDto>>("/api/members")
            .Summary("List all team members");
}

// Implement it — compiler enforces the return type matches the contract
[HttpGet]
public async Task<IActionResult> List(CancellationToken ct)
    => (await MembersContract.List.Invoke(async () =>
    {
        return await db.Members.ToListAsync(ct); // must return List<MemberDto>
    })).ToActionResult();

// Works with minimal APIs too — .Route avoids duplicating the route string
app.MapGet(MembersContract.List.Route, async (AppDb db, CancellationToken ct) =>
    (await MembersContract.List.Invoke(async () =>
    {
        return await db.Members.ToListAsync(ct);
    })).ToResult());  // you write ToResult() once, same pattern as ToActionResult()

Add --compile → runtime validation with Zod

dotnet rivet --project Api.csproj --output ./generated --compile

Rivet emits Zod 4 validators backed by fromJSONSchema() — a schemas.ts with standalone JSON Schema definitions and a validators.ts that wraps them:

// schemas.ts — standalone JSON Schema, usable with any validator
import type { core } from "zod";
type JSONSchema = core.JSONSchema.JSONSchema;

const $defs: Record<string, JSONSchema> = { /* all type definitions */ };
export const TaskItemSchema: JSONSchema = { "$ref": "#/$defs/TaskItem", "$defs": $defs };

// validators.ts — cached Zod schemas from the JSON Schema definitions
import { fromJSONSchema, z } from "zod";
import { TaskItemSchema } from "./schemas.js";

const _assertTaskItem = fromJSONSchema(TaskItemSchema);
export const assertTaskItem = (data: unknown): TaskItem => _assertTaskItem.parse(data) as TaskItem;

Every API response is validated at the network boundary — not just primitives, but full object shapes, nested types, and unions. If the server sends unexpected data, you get a clear error immediately — not a silent undefined three components later. Requires zod in your consumer project.

You can also emit just the schemas without validation wiring:

dotnet rivet --project Api.csproj --output ./generated --jsonschema

This writes schemas.ts only — use it with fromJSONSchema(), ajv, or any JSON Schema consumer.

Import OpenAPI → get C# contracts

Another team owns the API? Import their OpenAPI spec, get typed C# contracts, feed them back into the pipeline. The compiler tells you what broke when the upstream spec changes.

{
  "components": {
    "schemas": {
      "TaskDto": {
        "type": "object",
        "properties": {
          "id": { "type": "string", "format": "uuid" },
          "title": { "type": "string" },
          "priority": { "$ref": "#/components/schemas/Priority" }
        },
        "required": ["id", "title", "priority"]
      },
      "Priority": {
        "type": "string",
        "enum": ["low", "medium", "high", "critical"]
      }
    }
  },
  "paths": {
    "/api/tasks": {
      "get": {
        "tags": ["Tasks"],
        "summary": "List all tasks",
        "responses": {
          "200": {
            "content": { "application/json": { "schema": {
              "type": "array", "items": { "$ref": "#/components/schemas/TaskDto" }
            } } }
          }
        }
      }
    }
  }
}

dotnet rivet --from-openapi spec.json --namespace MyApp.Contracts --output ./src/

// Generated — sealed records, enums, typed contract with builder chain
public enum Priority { Low, Medium, High, Critical }

public sealed record TaskDto(Guid Id, string Title, Priority Priority);

[RivetContract]
public static class TasksContract
{
    public static readonly RouteDefinition<List<TaskDto>> List =
        Define.Get<List<TaskDto>>("/api/tasks")
            .Summary("List all tasks");
}

The importer handles JSON, form-encoded, binary (application/octet-stream → IFormFile), and text (text/* → string) content types. Endpoints with unsupported or schema-less content types are still generated but annotated with a // [rivet:unsupported ...] comment — see the OpenAPI Import guide for details.

Check contract coverage

dotnet rivet --project Api.csproj --check

warning: [MissingImplementation] MembersContract.Remove: expected DELETE /api/members/{id}, got (none)
warning: [RouteMismatch] MembersContract.UpdateRole: expected /api/members/{id}/role, got /api/members/{id}/update-role
Coverage: 2/4 endpoints covered, 1 mismatch(es), 1 missing.

Verifies that every contract endpoint has a matching handler implementation, with correct HTTP method and route. Useful in CI to catch missing or mismatched handlers.

List your routes

dotnet rivet --project Api.csproj --routes

  Method  Route                      Handler
  ──────  ─────────────────────────  ───────
  GET     /api/members               members.list
  POST    /api/members               members.invite
  DELETE  /api/members/{id}          members.remove
  PUT     /api/members/{id}/role     members.updateRole
4 route(s).

Documentation

Guides, reference, and architecture at maxanstey-meridian.github.io/rivet.

License

MIT