Routing & Handlers

The handler signature

In Express a handler receives (req, res, next). In Echo every handler has a single, uniform signature:

func(c echo.Context) error

echo.Context bundles the request, response writer, path parameters, query parameters, and helper methods. You return nil on success or an error to let Echo handle the failure response.

// Express handler
app.get('/books/:id', (req, res, next) => {
  const id = req.params.id;
  const book = findBook(id);
  if (!book) return res.status(404).json({ message: 'not found' });
  res.json(book);
});

// Echo handler
func getBook(c echo.Context) error {
    id := c.Param("id")
    book, err := findBook(id)
    if err != nil {
        return echo.NewHTTPError(http.StatusNotFound, "not found")
    }
    return c.JSON(http.StatusOK, book)
}

Registering routes

Echo’s routing API mirrors Express closely. Methods map directly to HTTP verbs.

// Express
app.get('/books',      listBooks);
app.post('/books',     createBook);
app.get('/books/:id',  getBook);
app.put('/books/:id',  updateBook);
app.delete('/books/:id', deleteBook);

// Echo
e.GET("/books",       listBooks)
e.POST("/books",      createBook)
e.GET("/books/:id",   getBook)
e.PUT("/books/:id",   updateBook)
e.DELETE("/books/:id", deleteBook)

Path parameters

c.Param("name") returns the string value of a named segment. The colon syntax :name is identical to Express.

// Express
app.get('/users/:id/posts/:postId', (req, res) => {
  const { id, postId } = req.params;
  res.json({ userId: id, postId });
});

// Echo
e.GET("/users/:id/posts/:postId", func(c echo.Context) error {
    userID  := c.Param("id")
    postID  := c.Param("postId")
    return c.JSON(http.StatusOK, map[string]string{
        "userId": userID,
        "postId": postID,
    })
})

Query parameters

c.QueryParam("name") reads a single query value. c.QueryParams() returns all of them as url.Values (a map[string][]string).

// Express
app.get('/books', (req, res) => {
  const { page = '1', limit = '10' } = req.query;
  res.json({ page, limit });
});

// Echo
e.GET("/books", func(c echo.Context) error {
    page  := c.QueryParam("page")
    limit := c.QueryParam("limit")
    if page == "" { page = "1" }
    if limit == "" { limit = "10" }
    return c.JSON(http.StatusOK, map[string]string{
        "page": page, "limit": limit,
    })
})

Attaching handlers to a struct (NestJS controller style)

NestJS controllers are classes. In Go the idiomatic equivalent is a struct whose methods are the handlers. Dependency injection happens through the struct’s fields.

// NestJS controller
@Controller('books')
export class BooksController {
  constructor(private readonly booksService: BooksService) {}

  @Get(':id')
  findOne(@Param('id') id: string) {
    return this.booksService.findOne(id);
  }
}

// Echo — handler struct (manual DI)
type BookHandler struct {
    store BookStore
}

func NewBookHandler(s BookStore) *BookHandler {
    return &BookHandler{store: s}
}

func (h *BookHandler) Get(c echo.Context) error {
    id := c.Param("id")
    book, err := h.store.FindByID(c.Request().Context(), id)
    if err != nil {
        return echo.NewHTTPError(http.StatusNotFound, err.Error())
    }
    return c.JSON(http.StatusOK, book)
}

// Registration in main.go:
// bh := NewBookHandler(store)
// e.GET("/books/:id", bh.Get)

🟦 Wildcard and any-depth routes

Echo supports wildcard segments with *:

// Matches /static/css/app.css, /static/js/bundle.js, etc.
e.GET("/static/*", staticHandler)

// Inside the handler:
path := c.Param("*")   // "css/app.css"

Use this for serving static files or proxying sub-paths.

Run this locally — it needs the Echo module and a network port.