Validator
Validators are directives that validate the value of a field, most commonly used in routes.
Route Validators
In most web frameworks, you need to write a lot of code to validate request bodies, query strings, and path parameters. Examples include webargs in Python, express-validator in Node.js, and zod in TypeScript.
AIScript provides a simple way to validate request components using directives.
Query String Validators
get /hello {
query {
@string(min_len=3, max_len=10)
name: str,
@in(["male", "female"])
gender: str
}
}
Request Body Validators
post /hello {
@json // or use @form to validate form data
body {
@regex(r"^\d{4}-\d{2}-\d{2}$")
birthdate: str,
@format(type="email")
email: str
}
}
Built-in Validators
AIScript provides several built-in validators for common validation scenarios, for the full list of validators, see Validator Reference.
String Validators
@string(min_len=3, max_len=20)
username: str
@regex(r"^[a-zA-Z0-9_]+$")
alphanumeric: str
@format(type="email")
email: str
@format(type="url")
website: str
Numeric Validators
@number(min=18, max=100)
age: int
@number(gt=0)
positive_value: float
Collection Validators
@array(min_len=1, max_len=5)
tags: array
@in(["admin", "user", "guest"])
role: str
Date Validators
@date(format="YYYY-MM-DD")
birthdate: str
@date(min="2022-01-01", max="2022-12-31")
event_date: str
Custom Error Messages
You can provide custom error messages for validation failures:
@string(min_len=8, error="Password must be at least 8 characters")
password: str
@in(["USD", "EUR", "GBP"], error="Currency must be one of USD, EUR, or GBP")
currency: str
Combining Validators
Multiple validators can be applied to a single field:
@string(min_len=3)
@regex(r"^[a-zA-Z0-9_]+$", error="Username can only contain letters, numbers, and underscores")
username: str
Validation Response
When validation fails, AIScript automatically returns an appropriate HTTP response with detailed error information:
{
"error": "Validation Error",
"details": [
{
"field": "username",
"message": "String must be at least 3 characters long"
},
{
"field": "address.zipcode",
"message": "Must match pattern ^\d{5}$"
}
]
}
Advanced Usage
Combining Multiple Validators
Multiple validators can be applied to a single field for complex validation scenarios:
post /api/user {
@json
body {
@string(min_len=3, max_len=20)
@regex(r"^[a-zA-Z0-9_]+$")
username: str,
@string(min_len=8)
@not(@in(["password", "12345678"]))
password: str
}
}
Custom Error Messages
Most validators accept an error parameter for custom error messages:
post /api/register {
@json
body {
@string(min_len=3, error="Username must be at least 3 characters")
username: str,
@format(type="email", error="Please provide a valid email address")
email: str
}
}
Conditional Validation
Use the @or directive for conditional validation:
post /api/payment {
@json
body {
@or(@regex(r"^\d{16}$"), @format(type="email"))
payment_type: str,
payment_details: str
}
}
By using validators, AIScript helps you build robust applications with clear data validation rules, reducing boilerplate code and ensuring consistent validation throughout your application.
