Requests & Validation

Retrieving input from users and validating it is the bread and butter of web development. Jazzy makes this painless.

Easiest Access: input()

The input() helper retrieves values from both query string parameters and the JSON body automatically. It unifies input access.

proc store(ctx: Context) =
  # Works for /store?name=Jazzy OR {"name": "Jazzy"}
  let name = ctx.input("name")

  # With a default value
  let role = ctx.input("role", "guest")

  ctx.text("Hello " & name)

Type-Safe Body Parsing

If you have a strict JSON structure, you can parse it directly into a type using bodyAs.

type UserDto = object
  username: string
  age: int

proc create(ctx: Context) =
  let dto = ctx.bodyAs(UserDto)
  # dto.username and dto.age are now typed values!
  echo dto.username

Validation

Jazzy includes a powerful validation engine inspired by Laravel. It automatically validates input and returns a 422 Unprocessable Entity response with error details if validation fails.

proc register(ctx: Context) =
  let data = ctx.validate(%*{
    "username": "required|min:3|max:20",
    "email":    "required|string",
    "age":      "int|min:18"
  })

  # If we reach here, validation PASSED.
  # 'data' contains the validated JsonNode.

  let user = DB.table("users").insert(data)
  ctx.json(%*{"status": "success", "id": user})

Available Rules

• required: The field must be present and not empty.
• string, int, bool: Type checks.
• min:X: Minimum length (string) or value (int).
• max:X: Maximum length (string) or value (int).
• in:foo,bar,baz: Value must be one of the listed options.

Handling Validation Errors manually

If you want to handle errors yourself instead of the automatic 422 response, you can wrap the call in a try/except block catching ValidationError.