Route Constraints
Type-safe parameter validation with route constraints.
2 minute read
Route constraints provide parameter validation that maps to OpenAPI schema types.
Typed Constraints
WhereInt(param string) *Route
Validates parameter as integer (OpenAPI: type: integer, format: int64).
r.GET("/users/:id", getUserHandler).WhereInt("id")
Matches:
/users/123✅/users/abc❌
WhereFloat(param string) *Route
Validates parameter as float (OpenAPI: type: number, format: double).
r.GET("/prices/:amount", getPriceHandler).WhereFloat("amount")
Matches:
/prices/19.99✅/prices/abc❌
WhereUUID(param string) *Route
Validates parameter as UUID (OpenAPI: type: string, format: uuid).
r.GET("/entities/:uuid", getEntityHandler).WhereUUID("uuid")
Matches:
/entities/550e8400-e29b-41d4-a716-446655440000✅/entities/not-a-uuid❌
WhereDate(param string) *Route
Validates parameter as date (OpenAPI: type: string, format: date).
r.GET("/orders/:date", getOrderHandler).WhereDate("date")
Matches:
/orders/2024-01-18✅/orders/invalid-date❌
WhereDateTime(param string) *Route
Validates parameter as date-time (OpenAPI: type: string, format: date-time).
r.GET("/events/:timestamp", getEventHandler).WhereDateTime("timestamp")
Matches:
/events/2024-01-18T10:30:00Z✅/events/invalid❌
WhereEnum(param string, values ...string) *Route
Validates parameter against enum values (OpenAPI: enum).
r.GET("/status/:state", getStatusHandler).WhereEnum("state", "active", "pending", "deleted")
Matches:
/status/active✅/status/invalid❌
Regex Constraints
WhereRegex(param, pattern string) *Route
Custom regex validation (OpenAPI: pattern).
// Alphanumeric only
r.GET("/slugs/:slug", getSlugHandler).WhereRegex("slug", `[a-zA-Z0-9]+`)
// Email validation
r.GET("/users/:email", getUserByEmailHandler).WhereRegex("email", `[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}`)
Multiple Constraints
Apply multiple constraints to the same route:
r.GET("/posts/:id/:slug", getPostHandler).
WhereInt("id").
WhereRegex("slug", `[a-zA-Z0-9-]+`)
Common Patterns
RESTful IDs
// Integer IDs
r.GET("/users/:id", getUserHandler).WhereInt("id")
r.PUT("/users/:id", updateUserHandler).WhereInt("id")
r.DELETE("/users/:id", deleteUserHandler).WhereInt("id")
// UUID IDs
r.GET("/entities/:uuid", getEntityHandler).WhereUUID("uuid")
Slugs and Identifiers
// Alphanumeric slugs
r.GET("/posts/:slug", getPostBySlugHandler).WhereRegex("slug", `[a-z0-9-]+`)
// Category identifiers
r.GET("/categories/:name", getCategoryHandler).WhereRegex("name", `[a-zA-Z0-9_-]+`)
Status and States
// Enum validation for states
r.GET("/orders/:status", getOrdersByStatusHandler).WhereEnum("status", "pending", "processing", "shipped", "delivered")
Complete Example
package main
import (
"net/http"
"rivaas.dev/router"
)
func main() {
r := router.New()
// Integer constraint
r.GET("/users/:id", getUserHandler).WhereInt("id")
// UUID constraint
r.GET("/entities/:uuid", getEntityHandler).WhereUUID("uuid")
// Enum constraint
r.GET("/status/:state", getStatusHandler).WhereEnum("state", "active", "inactive", "pending")
// Regex constraint
r.GET("/posts/:slug", getPostHandler).WhereRegex("slug", `[a-z0-9-]+`)
// Multiple constraints
r.GET("/articles/:id/:slug", getArticleHandler).
WhereInt("id").
WhereRegex("slug", `[a-z0-9-]+`)
http.ListenAndServe(":8080", r)
}
func getUserHandler(c *router.Context) {
c.JSON(200, map[string]string{"user_id": c.Param("id")})
}
func getEntityHandler(c *router.Context) {
c.JSON(200, map[string]string{"uuid": c.Param("uuid")})
}
func getStatusHandler(c *router.Context) {
c.JSON(200, map[string]string{"state": c.Param("state")})
}
func getPostHandler(c *router.Context) {
c.JSON(200, map[string]string{"slug": c.Param("slug")})
}
func getArticleHandler(c *router.Context) {
c.JSON(200, map[string]string{
"id": c.Param("id"),
"slug": c.Param("slug"),
})
}
Next Steps
- API Reference: See core types
- Route Patterns: Learn about route patterns
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