revert 37c74a5, closes #8

CHANGELOG.md

@@ -13,6 +13,11 @@
 **Note**: Gaps between patch versions are faulty/broken releases. **Note**: A feature tagged as Experimental is in a
 high state of flux, you're at risk of it changing without notice.
 
+# 0.9.3
+
+* **Bug Fix**
+  * revert 37c74a5e2038de063a950f9ba8d18b1f132ef450, closes #8 (@gcanti)
+
 # 0.9.2
 
 * **New Feature**

package.json

@@ -1,6 +1,6 @@
 {
   "name": "io-ts",
-  "version": "0.9.2",
+  "version": "0.9.3",
   "description": "TypeScript compatible runtime type system for IO validation",
   "files": ["lib"],
   "main": "lib/index.js",

src/index.ts

@@ -522,7 +522,7 @@ export const partial = <P extends Props>(
 ): PartialType<P, PartialOf<P>> => {
   const partials: Props = {}
   for (let k in props) {
-    partials[k] = union([undefinedType, props[k]])
+    partials[k] = union([props[k], undefinedType])
   }
   const partial = type(partials)
   return new PartialType(

test/helpers.ts

@@ -56,3 +56,12 @@ export const NumberFromString = new t.Type<string, number>(
 )
 
 export const IntegerFromString = t.refinement(NumberFromString, t.Integer.is, 'IntegerFromString')
+
+export function withDefault<T extends t.Any>(type: T, defaultValue: t.TypeOf<T>): t.Type<t.InputOf<T>, t.TypeOf<T>> {
+  return new t.Type(
+    `withDefault(${type.name}, ${JSON.stringify(defaultValue)})`,
+    type.is,
+    (v, c) => type.validate(v != null ? v : defaultValue, c),
+    type.serialize
+  )
+}

test/partial.ts

@@ -1,6 +1,13 @@
 import * as assert from 'assert'
 import * as t from '../src/index'
-import { assertSuccess, assertFailure, assertStrictEqual, DateFromNumber } from './helpers'
+import {
+  assertSuccess,
+  assertFailure,
+  assertStrictEqual,
+  DateFromNumber,
+  assertDeepEqual,
+  withDefault
+} from './helpers'
 
 describe('partial', () => {
   it('should succeed validating a valid value', () => {
@@ -36,8 +43,8 @@ describe('partial', () => {
   it('should fail validating an invalid value', () => {
     const T = t.partial({ a: t.number })
     assertFailure(t.validate({ a: 's' }, T), [
-      'Invalid value "s" supplied to : PartialType<{ a: number }>/a: (undefined | number)/0: undefined',
-      'Invalid value "s" supplied to : PartialType<{ a: number }>/a: (undefined | number)/1: number'
+      'Invalid value "s" supplied to : PartialType<{ a: number }>/a: (number | undefined)/0: number',
+      'Invalid value "s" supplied to : PartialType<{ a: number }>/a: (number | undefined)/1: undefined'
     ])
   })
 
@@ -64,4 +71,11 @@ describe('partial', () => {
     assert.strictEqual(T2.is({ a: 0 }), false)
     assert.strictEqual(T2.is(undefined), false)
   })
+
+  it('should support default values', () => {
+    const T = t.partial({
+      name: withDefault(t.string, 'foo')
+    })
+    assertDeepEqual(t.validate({}, T), { name: 'foo' })
+  })
 })