Fixes falsy default value issue

colinhacks · Sep 27, 2020 · c87fe1c · c87fe1c
1 parent c35fe04
commit c87fe1c
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Showing 5 changed files with 40 additions and 33 deletions.
diff --git a/README.md b/README.md
@@ -1596,7 +1596,7 @@ const stringWithDefault = z.transformer(
 );
 ```
 
-Equivalently you can express this using the built-in `.default()` method, available on all Zod schemas. A default value will be used if the schema is `null` or `undefined`.
+Equivalently you can express this using the built-in `.default()` method, available on all Zod schemas. The default value will be used if and only if the schema is `undefined`.
 
 ```ts
 z.string().default('default value');

diff --git a/src/__tests__/transformer.test.ts b/src/__tests__/transformer.test.ts
@@ -60,20 +60,25 @@ test('default', () => {
 });
 
 test('default when property is null or undefined', () => {
-  const data = z.object({
-    foo: z.boolean().nullable().default(true),
-    bar: z.boolean().default(true)
-  }).parse({ foo: null });
+  const data = z
+    .object({
+      foo: z
+        .boolean()
+        .nullable()
+        .default(true),
+      bar: z.boolean().default(true),
+    })
+    .parse({ foo: null });
 
-  expect(data).toEqual({ foo: true, bar: true });
+  expect(data).toEqual({ foo: null, bar: true });
 });
 
 test('default with falsy values', () => {
   const schema = z.object({
     emptyStr: z.string().default('def'),
     zero: z.number().default(5),
-    falseBoolean: z.boolean().default(true)
-  })
+    falseBoolean: z.boolean().default(true),
+  });
   const input = { emptyStr: '', zero: 0, falseBoolean: true };
   const output = schema.parse(input);
   // defaults are not supposed to be used

diff --git a/src/parser.ts b/src/parser.ts
@@ -375,20 +375,22 @@ export const ZodParser = (schema: z.ZodType<any>) => (
         if (!keyValidator) continue;
 
         // check if schema and value are both optional
-        try {
-          keyValidator.parse(undefined, {
-            ...params,
-            path: [...params.path, key],
-          });
 
-          // const keyDataType = getParsedType(data[key]);
-          if (!Object.keys(data).includes(key)) {
-            // schema is optional
-            // data is undefined
-            // don't explicity add undefined to outut
-            continue;
-          }
-        } catch (err) {}
+        // const keyDataType = getParsedType(data[key]);
+        if (!Object.keys(data).includes(key)) {
+          try {
+            const output = keyValidator.parse(undefined, {
+              ...params,
+              path: [...params.path, key],
+            });
+            if (output === undefined) {
+              // schema is optional
+              // data is undefined
+              // don't explicity add undefined to outut
+              continue;
+            }
+          } catch (err) {}
+        }
 
         objectPromises[key] = new PseudoPromise().then(() => {
           try {

diff --git a/src/playground.ts b/src/playground.ts
@@ -1,17 +1,17 @@
 import * as z from '.';
 
 const run = async () => {
-  const SNamedEntity = z.object({
-    id: z.string(),
-    set: z.string().optional(),
-    unset: z.string().optional(),
-  });
-  const result = await SNamedEntity.parse({
-    id: 'asdf',
-    set: undefined,
-  });
-  console.log(result);
-  console.log(Object.keys(result));
+  const data = z
+    .object({
+      foo: z
+        .boolean()
+        .nullable()
+        .default(true),
+      bar: z.boolean().default(true),
+    })
+    .parse({ foo: null });
+
+  console.log(data);
 };
 run();
 

diff --git a/src/types/base.ts b/src/types/base.ts
@@ -324,7 +324,7 @@ export abstract class ZodType<
     def: T,
   ) => ZodTransformer<Opt, this> = def => {
     return ZodTransformer.create(this.optional(), this, (x: any) => {
-      return (x ?? def) as any;
+      return x === undefined ? def : x;
     }) as any;
   };