From 3824103d5726787eeab07e8db773e583f8d821ce Mon Sep 17 00:00:00 2001
From: Abdelrahman Awad <logaretm1@gmail.com>
Date: Sat, 31 Jul 2021 15:03:11 +0200
Subject: [PATCH] FIX: avoid setting the absent value to checkboxes without
 unchecked value closes #3424

---
 packages/vee-validate/src/Field.ts            |  9 ++++--
 packages/vee-validate/src/symbols.ts          |  2 +-
 packages/vee-validate/src/utils/assertions.ts |  4 +--
 packages/vee-validate/tests/Form.spec.ts      | 28 +++++++++++++++++++
 4 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/packages/vee-validate/src/Field.ts b/packages/vee-validate/src/Field.ts
index add84a002..d07f9c04d 100644
--- a/packages/vee-validate/src/Field.ts
+++ b/packages/vee-validate/src/Field.ts
@@ -3,7 +3,7 @@ import { getConfig } from './config';
 import { useField } from './useField';
 import { normalizeChildren, hasCheckedAttr, shouldHaveValueBinding, isPropPresent } from './utils';
 import { toNumber } from '../../shared';
-import { EMPTY_VALUE } from './symbols';
+import { IS_ABSENT } from './symbols';
 
 interface ValidationTriggersProps {
   validateOnMount: boolean;
@@ -64,7 +64,7 @@ export const Field = defineComponent({
     },
     modelValue: {
       type: null,
-      default: EMPTY_VALUE,
+      default: IS_ABSENT,
     },
     modelModifiers: {
       type: null,
@@ -162,6 +162,11 @@ export const Field = defineComponent({
 
     const modelValue = toRef(props, 'modelValue');
     watch(modelValue, newModelValue => {
+      // Don't attempt to sync absent values
+      if ((newModelValue as any) === IS_ABSENT && value.value === undefined) {
+        return;
+      }
+
       if (newModelValue !== applyModifiers(value.value, props.modelModifiers)) {
         value.value = newModelValue;
         validateField();
diff --git a/packages/vee-validate/src/symbols.ts b/packages/vee-validate/src/symbols.ts
index 9b3b4cc04..63953115b 100644
--- a/packages/vee-validate/src/symbols.ts
+++ b/packages/vee-validate/src/symbols.ts
@@ -12,4 +12,4 @@ export const FormInitialValuesKey: InjectionKey<ComputedRef<Record<string, unkno
 
 export const FieldContextKey: InjectionKey<PrivateFieldContext<unknown>> = Symbol('vee-validate-field-instance');
 
-export const EMPTY_VALUE = Symbol('Default empty value');
+export const IS_ABSENT = Symbol('Default empty value');
diff --git a/packages/vee-validate/src/utils/assertions.ts b/packages/vee-validate/src/utils/assertions.ts
index 88d201415..6da184711 100644
--- a/packages/vee-validate/src/utils/assertions.ts
+++ b/packages/vee-validate/src/utils/assertions.ts
@@ -1,6 +1,6 @@
 import { Locator, YupValidator } from '../types';
 import { isCallable, isObject } from '../../../shared';
-import { EMPTY_VALUE } from '../symbols';
+import { IS_ABSENT } from '../symbols';
 
 export function isLocator(value: unknown): value is Locator {
   return isCallable(value) && !!(value as Locator).__locatorRef;
@@ -102,5 +102,5 @@ export function isEvent(evt: unknown): evt is Event {
 }
 
 export function isPropPresent(obj: Record<string, unknown>, prop: string) {
-  return prop in obj && obj[prop] !== EMPTY_VALUE;
+  return prop in obj && obj[prop] !== IS_ABSENT;
 }
diff --git a/packages/vee-validate/tests/Form.spec.ts b/packages/vee-validate/tests/Form.spec.ts
index 4c616497c..4a9e38fd6 100644
--- a/packages/vee-validate/tests/Form.spec.ts
+++ b/packages/vee-validate/tests/Form.spec.ts
@@ -2177,4 +2177,32 @@ describe('<Form />', () => {
     expect(fieldError.textContent).toBe(REQUIRED_MESSAGE);
     expect(meta.textContent).toBe('true');
   });
+
+  // 3424
+  test('Checkbox with v-model should not propagate the empty value symbol', async () => {
+    const value = ref('');
+    mountWithHoc({
+      setup() {
+        return {
+          value,
+        };
+      },
+      template: `
+      <VForm>
+        <Field name="check" type="checkbox" v-model="value" value="CHECKED" /> 
+      </VForm>
+    `,
+    });
+
+    await flushPromises();
+    const input = document.querySelector('input') as HTMLInputElement;
+    setChecked(input, true);
+    await flushPromises();
+    expect(value.value).toBe('CHECKED');
+
+    setChecked(input, false);
+    await flushPromises();
+
+    expect(value.value).toBe(undefined);
+  });
 });