Data Parser
Functions to build, compose, and run immutable validators. DataParser.* or DP.* describes the expected shape of data, returns an Either (parse / asyncParse), and produces structured errors ready to be serialized.
How to import?
The library exposes the DDataParser, DDataParserCoerce, and DDataParserExtended namespaces from the main entry or via direct import (tree-shaking friendly), which lets you only load what you need.
// DataParser
import { DDataParser, DP } from "@duplojs/utils";
import * as DDataParser from "@duplojs/utils/dataParser";
import * as DP from "@duplojs/utils/dataParser";
// DataParserCoerce
import { DDataParserCoerce, DPC } from "@duplojs/utils";
import * as DDataParserCoerce from "@duplojs/utils/dataParserCoerce";
import * as DPC from "@duplojs/utils/dataParserCoerce";
// DataParserExtended
import { DDataParserExtended, DPE } from "@duplojs/utils";Checker contract
The checker contract is centered on parser output type: a checker is compatible when its input type matches Output<Parser>. Checkers are modeled through this type-compatibility contract.
Some checkers also refine the parser type. checkerRefine(...) narrows the output when the predicate is a TypeScript type guard, checkerEmail() narrows strings to an email template-literal type, and array min/max checkers can add non-empty tuple and MaxElements<N> information when their bounds are literal numbers. These refinements are applied to both classic and extended parsers, and then propagate to Clean constraints and NewTypes.
Primitive parsers
string
Validates strings: min, max, regex, email, url, uuid checkers, with coercion support (42 → normalized "42").
number
Validates numbers with min, max, int constraints and coercion support (Number(value)).
boolean
Validates booleans or converts them from common strings ("true", "1", etc.).
bigint
Validates bigint with dedicated min/max checkers, useful for high-precision identifiers.
date
Validates TheDate, SerializedTheDate, and native Date (with optional timestamp/string coercion) before converting to TheDate.
time
Validates TheTime, SerializedTheTime, and safe numeric values, with min/max checkers and optional coercion.
literal
Enforces an exact output value ("admin", 42, true, etc.).
templateLiteral
Builds a parser from a TemplateLiteral pattern (e.g. order-${number}).
nil
Accepts only null and allows adding specific checkers.
empty
Validates absence of a value (undefined) in a schema.
unknown
Accepts any value while keeping the ability to add checkers/refine.
Composed structures
object
Declares an object structure, handles optional keys, static inference, and contextualized errors (path user.email).
array
Validates homogeneous arrays, with min, max, nonEmpty, etc. checkers.
tuple
Defines an ordered sequence of parsers with fixed or variable sizes.
record
Describes a key/value map with separate validation for keys and values.
union
Tries multiple parsers in order, returns the first that succeeds, and otherwise reports detailed errors.
Variants & optionality
optional
Allows undefined while keeping validation of the present value.
nullable
Allows null with native support for additional checkers.
lazy
Declares recursive schemas (e.g. trees, nested categories) thanks to a deferred function.
Pipelines & business logic
pipe
Composes multiple parsers to chain coercion, validation, transformation, and refinements.
transform
Transforms a parser result via a controlled function (e.g. string → URL).
refine
Adds custom rules (async/sync) with specific messages and metadata.
recover
Intercepts errors to return an alternative value (fallback) or trigger business logic.
errorHandler
Reassigns issue messages after parsing, useful when user-facing messages must be declared after the schema.
Runtime helpers
isAsynchronous
Tells whether a parser (or nested parsers) requires async execution.
Coercion
coerce.*
Placeholder space for coercive variants (coerce.string, coerce.number, coerce.boolean, coerce.date, etc.) when you must normalize data before strict validation.