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effect-extras

FormDataX overview

Helpers for decoding FormData with Effect Schema.

Added in v0.0.0

Table of contents

conversions

decodeSync

Decodes a FormData into a typed value using a Schema, throwing on validation failure.

Built on v4’s native Schema.fromFormData, which first parses the FormData entries into a nested tree record (bracket-path notation is supported) and then decodes that tree with the provided inner schema. For schemas with non-string fields (for example Schema.Int), wrap the inner schema in Schema.toCodecStringTree(schema, { keepDeclarations: true }) so the string → number/boolean coercion happens. Usable only with schemas that have no decoding services — this is enforced at the type level via S["DecodingServices"] = never — and it throws synchronously when the input fails validation.

Signature

export declare const decodeSync: {
  <S extends Schema.Top & { readonly DecodingServices: never }>(formData: FormData, schema: S): S["Type"]
  <S extends Schema.Top & { readonly DecodingServices: never }>(schema: S): (formData: FormData) => S["Type"]
}

Example

import { Schema } from "effect"
import { FormDataX } from "@nunofyobiz/effect-extras"

const formData = new FormData()
formData.append("name", "John")
formData.append("age", "30")

const result = FormDataX.decodeSync(formData, Schema.Struct({ name: Schema.String, age: Schema.NumberFromString }))

assert.deepStrictEqual(result, { name: "John", age: 30 })

Added in v0.0.0