feat(core): form reset field utility function

Author: Harry Whorlow

packages/form-core/src/FormApi.ts

@@ -1715,6 +1715,9 @@ export class FormApi<
     })
   }
 
+  /**
+   * resets every field's meta
+   */
   resetFieldMeta = <TField extends DeepKeys<TFormData>>(
     fieldMeta: Record<TField, AnyFieldMeta>,
   ): Record<TField, AnyFieldMeta> => {
@@ -1956,6 +1959,36 @@ export class FormApi<
     this.validateField(`${field}[${index1}]` as DeepKeys<TFormData>, 'change')
     this.validateField(`${field}[${index2}]` as DeepKeys<TFormData>, 'change')
   }
+
+  /**
+   * Resets the field value and meta to default state
+   */
+  resetField = <TField extends DeepKeys<TFormData>>(field: TField) => {
+    this.baseStore.setState((prev) => {
+      return {
+        ...prev,
+        fieldMetaBase: {
+          ...prev.fieldMetaBase,
+          [field]: {
+            isValidating: false,
+            isTouched: false,
+            isBlurred: false,
+            isDirty: false,
+            isPristine: true,
+            errors: [],
+            errorMap: {},
+          },
+        },
+        values: {
+          ...prev.values,
+          [field]:
+            this.options.defaultValues &&
+            this.options.defaultValues[field as keyof TFormData],
+        },
+      }
+    })
+  }
+
   /**
    * Updates the form's errorMap
    */

packages/form-core/tests/FormApi.spec.ts

@@ -2864,3 +2864,26 @@ it('should update isSubmitSuccessful correctly during form submission', async ()
 
   expect(form.state.isSubmitSuccessful).toBe(false)
 })
+
+it('should reset the fields value and meta to default state', async () => {
+  const form = new FormApi({
+    defaultValues: {
+      name: 'tony',
+    } as { name: string },
+  })
+  form.mount()
+  const field = new FieldApi({
+    form,
+    name: 'name',
+  })
+
+  field.mount()
+  field.setValue('hawk')
+
+  expect(form.state.values.name).toStrictEqual('hawk')
+  expect(field.state.meta.isTouched).toBe(true)
+
+  form.resetField('name')
+  expect(form.state.values.name).toStrictEqual('tony')
+  expect(field.state.meta.isTouched).toBe(false)
+})