Echo Web Framework

Echo v5 replaces the old ParamNames() and ParamValues() methods with a structured PathValues type. This type allows for more efficient handling of path parameters.

PathValue Structure:

• Name: The parameter name.
• Value: The parameter value.

Methods:

• PathValues.Get(name string) (string, bool): Retrieves a value by name.
• PathValues.GetOr(name string, defaultValue string) string: Retrieves a value or returns a default.

Context Integration:

• (c *Context) PathValues() PathValues: Returns the current path values.
• (c *Context) SetPathValues(pathValues PathValues): Sets the path values.

type PathValue struct {
    Name  string
    Value string
}

type PathValues []PathValue

func (p PathValues) Get(name string) (string, bool)
func (p PathValues) GetOr(name string, defaultValue string) string

func (c *Context) PathValues() PathValues
func (c *Context) SetPathValues(pathValues PathValues)

When creating custom middleware for the Echo framework, follow these guidelines to ensure compatibility and robust error handling:

• Avoid Panics in Creators: Do not use panic inside middleware creator functions when handling invalid configurations. Instead, prefer returning errors if the configuration is invalid.
• Error Handling in Request Flow: When an error occurs during request handling within a middleware, do not simply call c.Error() and return nil. Instead, return the error from the middleware function. This allows preceding middlewares in the call chain to implement specific logic for handling returned errors.
• Use Configuration Structs: Implement the MiddlewareConfigurator interface for your middleware configuration structs. This allows you to explicitly decide whether the middleware should panic or return errors when encountering configuration issues.
• Standardize Context Placement: When including echo.Context in function signatures or struct fields, always make it the first parameter. This ensures consistency across all functions that utilize the Echo context.

To create a basic Echo server, initialize a new Echo instance using echo.New(), define your routes, and start the server with e.Start(address). You can also use middleware like middleware.RequestLogger() and middleware.Recover() to enhance functionality.

Handlers receive an *echo.Context and should return an error.

package main

import (
  "github.com/labstack/echo/v5"
  "github.com/labstack/echo/v5/middleware"
  "log/slog"
  "net/http"
)

func main() {
  // Echo instance
  e := echo.New()

  // Middleware
  e.Use(middleware.RequestLogger()) // use the RequestLogger middleware with slog logger
  e.Use(middleware.Recover())       // recover panics as errors for proper error handling

  // Routes
  e.GET("/", hello)

  // Start server
  if err := e.Start(":8080"); err != nil {
    slog.Error("failed to start server", "error", err)
  }
}

// Handler
func hello(c *echo.Context) error {
  return c.String(http.StatusOK, "Hello, World!")
}

To migrate an existing project from Echo v4 to v5, follow these primary steps:

1. Update Imports: Change all echo/v4 imports to echo/v5.
2. Update Context Type: Change all occurrences of echo.Context to *echo.Context (it is now a pointer).
3. Update Handler Signatures: Ensure all handlers accept *echo.Context.
4. Update Error Handlers: The HTTPErrorHandler signature has swapped parameters from (err, c) to (c, err).
5. Update Server Startup: Use echo.StartConfig for advanced configurations instead of specialized Start methods.
6. Update Router Access: Access routes via e.Router().Routes() instead of e.Routes().

On Linux, you can automate the import and context pointer updates using sed:

find . -type f -name "*.go" -exec sed -i 's/ echo.Context/ *echo.Context/g' {} +
find . -type f -name "echo\/v4" -exec sed -i 's/echo\/v5/g' {} +