Validate - Ecko Std Lib Package

A data/input validation library for Ecko, written in Ecko. Validate a form submission, an API body, or a config map against a schema of composable rules, and get back every error at once.

Built on Ecko's first-class functions: a validator is just a function |value| -> null (pass) | message (fail), implemented with std.re and the builtins.

Install

ecko get github.com/ecko-lang/validate

ecko get vendors the package under ./vendor/github.com/ecko-lang/validate/ and pins a file-tree hash in ecko.sum.

Usage

import validate
v = validate                       # `import ... as` is not supported yet

schema = {
    name:  [v.required(), v.string(), v.min_len(2)],
    email: [v.required(), v.email()],
    age:   [v.int(), v.min(18)],
    role:  [v.one_of(["admin", "member", "guest"])],
    tags:  [v.each(v.string())],
}

errors = v.check(data, schema)     # {} = valid, else { field: [messages] }

if v.is_valid(data, schema) { ... }

# validate() returns the data, or raises a kind-"validation" error you can catch
clean = try { v.validate(data, schema) } catch (e) { get(e, "errors") }

Errors are collected, not fail-fast

v.check(
    { name: "A", email: "nope", age: 15 },
    { name: [v.required(), v.min_len(2)], email: [v.email()], age: [v.min(18)] },
)
# {
#   name:  ["must be at least 2 characters"],
#   email: ["must be a valid email"],
#   age:   ["must be at least 18"],
# }

How it works

Each validator checks exactly one concern and passes (null) on a null or wrong-typed value - so [v.required(), v.int(), v.min(18)] on a missing field yields exactly ["is required"] (no cascade), on "abc" yields ["must be a whole number"], and never crashes by running < on a string. Fields are optional by default; required() is the only rule that fails on null. There is no coercion - validation checks, it never transforms.

A custom rule is just a function:

even = |x| if x == null { null } else if x % 2 == 0 { null } else { "must be even" }
schema = { n: [v.int(), even] }

Validators

Group	Validators
Presence	required(), optional()
Types	string(), int(), float(), number(), bool(), list(), map()
Numbers	min(n), max(n), between(lo, hi), positive(), negative()
Strings	min_len(n), max_len(n), len_between(lo, hi), pattern(re, msg?), email(), url()
Membership	one_of(options)
Collections	non_empty(), each(validator)
Nested	shape(schema)

Runner

Function	Description
check(data, schema)	{ field: [messages] } - empty means valid
is_valid(data, schema)	Bool
validate(data, schema)	Returns data, or raises a kind-"validation" error carrying the error map
check_value(value, rules)	Run a rule list against a single value → [messages]

Testing

ecko test tests/

Offline and deterministic. example.ecko is a runnable signup-form demo.

License

MIT - see LICENSE.