Handler

HandlerFunc

type HandlerFunc func(c *Ctx) error

The base handler type. Every route handler and middleware is a HandlerFunc.

app.Get("/hello", func(c *kruda.Ctx) error {
    return c.Text("Hello!")
})

MiddlewareFunc

type MiddlewareFunc = HandlerFunc

MiddlewareFunc is a type alias for HandlerFunc. They are fully interchangeable.

func MyMiddleware(c *kruda.Ctx) error {
    // before handler
    err := c.Next()
    // after handler
    return err
}

C[T] — Typed Context

type C[T any] struct {
    *Ctx
    In T // parsed input from request
}

C[T] extends Ctx with a typed In field. The request body, route parameters, and query parameters are automatically parsed and validated into T before the handler runs.

Typed Handler Registration

Package-level generic functions register typed handlers with pre-compiled binding and validation:

func Get[In any, Out any](app *App, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func Post[In any, Out any](app *App, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func Put[In any, Out any](app *App, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func Delete[In any, Out any](app *App, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func Patch[In any, Out any](app *App, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)

type CreateUserInput struct {
    Name  string `json:"name"  validate:"required"`
    Email string `json:"email" validate:"required,email"`
}

type User struct {
    ID    string `json:"id"`
    Name  string `json:"name"`
}

kruda.Post[CreateUserInput, User](app, "/users", func(c *kruda.C[CreateUserInput]) (*User, error) {
    return &User{ID: "1", Name: c.In.Name}, nil
})

Short Handlers (no error return)

For prototyping — panics are caught by Recovery middleware:

func GetX[In any, Out any](app *App, path string, handler func(*C[In]) *Out, opts ...RouteOption)
func PostX[In any, Out any](app *App, path string, handler func(*C[In]) *Out, opts ...RouteOption)
func PutX[In any, Out any](app *App, path string, handler func(*C[In]) *Out, opts ...RouteOption)
func DeleteX[In any, Out any](app *App, path string, handler func(*C[In]) *Out, opts ...RouteOption)
func PatchX[In any, Out any](app *App, path string, handler func(*C[In]) *Out, opts ...RouteOption)

Group Typed Handlers

func GroupGet[In any, Out any](g *Group, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func GroupPost[In any, Out any](g *Group, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func GroupPut[In any, Out any](g *Group, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func GroupDelete[In any, Out any](g *Group, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)
func GroupPatch[In any, Out any](g *Group, path string, handler func(*C[In]) (*Out, error), opts ...RouteOption)

RouteOption

type RouteOption func(*routeConfig)

WithDescription

func WithDescription(desc string) RouteOption

Sets a route description (used by OpenAPI).

WithTags

func WithTags(tags ...string) RouteOption

Sets route tags (used by OpenAPI).

Struct Tag Binding

The typed handler binds request data based on struct tags:

type GetUserInput struct {
    ID     string `param:"id"`         // route parameter :id
    Fields string `query:"fields"`     // query string ?fields=...
}

type UpdateUserInput struct {
    ID   string `param:"id"`           // route parameter
    Name string `json:"name"`          // JSON body field
    Age  int    `json:"age"`           // JSON body field
}

Binding order:

1. param tags — from route parameters
2. query tags — from query string
3. json tags — from request body
4. header tags — from request headers

Validation

After binding, validation runs automatically using validate struct tags:

type Input struct {
    Name string `json:"name" validate:"required,min=2,max=100"`
    Age  int    `json:"age"  validate:"min=0,max=150"`
}

Validation failures return HTTP 422 with structured error details.