Create Controller

Create Controller

Creates a controller that handles HTTP requests and responses. Controllers are thin layers that extract data from requests, call services, and return responses.

Quick Reference

Location: src/controllers/{entity-name}.controller.ts Naming: Singular, kebab-case (e.g., note.controller.ts, user.controller.ts)

Prerequisites

Before creating a controller, ensure you have:

1. Schema created with request/response types (src/schemas/{entity-name}.schema.ts)
2. Service created (src/services/{entity-name}.service.ts)

Instructions

Step 1: Create the Controller File

Create src/controllers/{entity-name}.controller.ts

Step 2: Import Dependencies

import type { Context } from "hono";
import { {Entity}Service } from "@/services/{entity-name}.service";
import type { EntityIdParamType } from "@/schemas/shared.schema";
import type {
  Create{Entity}Type,
  {Entity}QueryParamsType,
  Update{Entity}Type,
} from "@/schemas/{entity-name}.schema";
import type { AppEnv } from "@/schemas/app-env.schema";
import type { AuthenticatedUserContextType } from "@/schemas/user.schemas";
import { NotFoundError } from "@/errors";

Step 3: Create the Controller Class

export class {Entity}Controller {
  private {entity}Service: {Entity}Service;

  constructor({entity}Service?: {Entity}Service) {
    if ({entity}Service) {
      this.{entity}Service = {entity}Service;
    } else {
      this.{entity}Service = new {Entity}Service();
    }
  }

  // Handler methods...
}

Step 4: Implement CRUD Handlers

getAll

getAll = async (c: Context<AppEnv>): Promise<Response> => {
  const user = c.var.user as AuthenticatedUserContextType;
  const query = c.var.validatedQuery as {Entity}QueryParamsType;
  const {entities} = await this.{entity}Service.getAll(query, user);
  return c.json({entities});
};

getById

getById = async (c: Context<AppEnv>): Promise<Response> => {
  const user = c.var.user as AuthenticatedUserContextType;
  const { id } = c.var.validatedParams as EntityIdParamType;
  const {entity} = await this.{entity}Service.getById(id, user);
  if (!{entity}) throw new NotFoundError();
  return c.json({entity});
};

create

create = async (c: Context<AppEnv>): Promise<Response> => {
  const user = c.var.user as AuthenticatedUserContextType;
  const body = c.var.validatedBody as Create{Entity}Type;
  const {entity} = await this.{entity}Service.create(body, user);
  return c.json({entity});
};

update

update = async (c: Context<AppEnv>): Promise<Response> => {
  const user = c.var.user as AuthenticatedUserContextType;
  const { id } = c.var.validatedParams as EntityIdParamType;
  const body = c.var.validatedBody as Update{Entity}Type;
  const {entity} = await this.{entity}Service.update(id, body, user);
  if (!{entity}) throw new NotFoundError();
  return c.json({entity});
};

delete

delete = async (c: Context<AppEnv>): Promise<Response> => {
  const user = c.var.user as AuthenticatedUserContextType;
  const { id } = c.var.validatedParams as EntityIdParamType;
  const success = await this.{entity}Service.delete(id, user);
  if (!success) throw new NotFoundError();
  return c.json({ message: "{Entity} deleted successfully" });
};

Patterns & Rules

Handler Method Pattern

Use arrow functions assigned to class properties for handlers:

// Correct - arrow function maintains `this` binding
getAll = async (c: Context<AppEnv>): Promise<Response> => {
  // ...
};

// Wrong - regular method loses `this` when passed as callback
async getAll(c: Context<AppEnv>): Promise<Response> {
  // ...
}

Context Variables

Data is pre-validated by middleware and stored in c.var:

// User from auth middleware
const user = c.var.user as AuthenticatedUserContextType;

// Validated query params from validation middleware
const query = c.var.validatedQuery as {Entity}QueryParamsType;

// Validated request body from validation middleware
const body = c.var.validatedBody as Create{Entity}Type;

// Validated URL params from validation middleware
const { id } = c.var.validatedParams as EntityIdParamType;

Dependency Injection

Allow service injection for testing:

constructor({entity}Service?: {Entity}Service) {
  if ({entity}Service) {
    this.{entity}Service = {entity}Service;
  } else {
    this.{entity}Service = new {Entity}Service();
  }
}

Error Handling

Controllers throw domain errors - global error handler converts to HTTP:

// Service returns null for not found
const {entity} = await this.{entity}Service.getById(id, user);
if (!{entity}) throw new NotFoundError();

// Service throws UnauthorizedError for permission denied
// Let it propagate - global handler catches it

Response Format

Use c.json() for all responses:

// Return entity
return c.json({ entity });

// Return paginated result
return c.json({ entities }); // { data: [...], total: n, page: 1, ... }

// Return success message
return c.json({ message: "{Entity} deleted successfully" });

AppEnv Type

Always type Context with AppEnv:

import type { AppEnv } from "@/schemas/app-env.schema";

getAll = async (c: Context<AppEnv>): Promise<Response> => {
  // c.var is properly typed
};

The AppEnv interface provides types for:

• c.var.user - Authenticated user context
• c.var.validatedQuery - Validated query parameters
• c.var.validatedBody - Validated request body
• c.var.validatedParams - Validated URL parameters

Complete Example

See REFERENCE.md for a complete NoteController implementation.

What NOT to Do

• Do NOT validate input in controllers (use validation middleware)
• Do NOT access c.req.json() directly (use c.var.validatedBody)
• Do NOT catch errors (let global error handler catch them)
• Do NOT return HTTP status codes manually (use domain errors)
• Do NOT put business logic in controllers (that's for services)
• Do NOT use regular methods (use arrow functions for this binding)

See Also

• create-routes - Wire controller handlers to routes with middleware
• create-middleware - Create validation and auth middleware
• test-controller - Test controller handlers