feat(core): add field listeners

docs/config.json

@@ -101,6 +101,10 @@
               "label": "Linked Fields",
               "to": "framework/react/guides/linked-fields"
             },
+            {
+              "label": "Listeners",
+              "to": "framework/react/guides/listeners"
+            },
             {
               "label": "UI Libraries",
               "to": "framework/react/guides/ui-libraries"

docs/framework/angular/guides/basic-concepts.md

@@ -187,6 +187,41 @@ class AppComponent {
 }
 ```
 
+## Listeners
+
+`@tanstack/angular-form` allows you to react to specific triggers and "listen" to them to dispatch side effects.
+
+Example:
+
+```angular-ts
+@Component({
+  selector: 'app-root',
+  standalone: true,
+  imports: [TanStackField],
+  template: `
+    <ng-container
+      [tanstackField]="form"
+      name="country"
+      [listeners]="{
+        onChange: onCountryChange
+      }"
+      #country="field"
+    ></ng-container>
+  `,
+})
+
+...
+
+onCountryChange: FieldListenerFn<any, any, any, any, string> = ({
+    value,
+  }) => {
+    console.log(`Country changed to: ${value}, resetting province`)
+    this.form.setFieldValue('province', '')
+  }
+```
+
+More information can be found at [Listeners](./listeners.md)
+
 ## Array Fields
 
 Array fields allow you to manage a list of values within a form, such as a list of hobbies. You can create an array field using the `tanstackField` directive.

docs/framework/angular/guides/listeners.md

@@ -0,0 +1,61 @@
+---
+id: listeners
+title: Side effects for event triggers
+---
+
+For situations where you want to "affect" or "react" to triggers, there's the listener API. For example, if you, as the developer, want to reset a form field as a result of another field changing, you would use the listener API.
+
+Imagine the following user flow:
+
+- User selects a country from a drop-down.
+- User then selects a province from another drop-down.
+- User changes the selected country to a different one.
+
+In this example, when the user changes the country, the selected province needs to be reset as it's no longer valid. With the listener API, we can subscribe to the onChange event and dispatch a reset to the field "province" when the listener is fired.
+
+Events that can be "listened" to are:
+
+- onChange
+- onBlur
+- onMount
+- onSubmit
+
+```angular-ts
+@Component({
+  selector: 'app-root',
+  standalone: true,
+  imports: [TanStackField],
+  template: `
+    <ng-container
+      [tanstackField]="form"
+      name="country"
+      [listeners]="{
+        onChange: onCountryChange
+      }"
+      #country="field"
+    ></ng-container>
+
+    <ng-container
+      [tanstackField]="form"
+      name="province"
+      #province="field"
+    ></ng-container>
+  `,
+})
+
+export class AppComponent {
+  form = injectForm({
+    defaultValues: {
+      country: '',
+      province: '',
+    },
+  })
+
+  onCountryChange: FieldListenerFn<any, any, any, any, string> = ({
+    value,
+  }) => {
+    console.log(`Country changed to: ${value}, resetting province`)
+    this.form.setFieldValue('province', '')
+  }
+}
+```

docs/framework/angular/reference/classes/tanstackfield.md

@@ -46,7 +46,7 @@ api: FieldApi<TParentData, TName, TFieldValidator, TFormValidator, TData>;
 
 #### Defined in
 
-[tanstack-field.directive.ts:58](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L58)
+[tanstack-field.directive.ts:62](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L62)
 
 ***
 
@@ -64,7 +64,7 @@ If `true`, always run async validation, even if there are errors emitted during
 
 #### Defined in
 
-[tanstack-field.directive.ts:47](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L47)
+[tanstack-field.directive.ts:48](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L48)
 
 ***
 
@@ -82,7 +82,7 @@ The default time to debounce async validation if there is not a more specific de
 
 #### Defined in
 
-[tanstack-field.directive.ts:46](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L46)
+[tanstack-field.directive.ts:47](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L47)
 
 ***
 
@@ -100,7 +100,7 @@ An optional object with default metadata for the field.
 
 #### Defined in
 
-[tanstack-field.directive.ts:56](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L56)
+[tanstack-field.directive.ts:60](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L60)
 
 ***
 
@@ -118,7 +118,25 @@ An optional default value for the field.
 
 #### Defined in
 
-[tanstack-field.directive.ts:45](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L45)
+[tanstack-field.directive.ts:46](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L46)
+
+***
+
+### listeners?
+
+```ts
+optional listeners: NoInfer<FieldListeners<TParentData, TName, TFieldValidator, TFormValidator, TData>>;
+```
+
+A list of listeners which attach to the corresponding events
+
+#### Implementation of
+
+`FieldOptions.listeners`
+
+#### Defined in
+
+[tanstack-field.directive.ts:57](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L57)
 
 ***
 
@@ -136,7 +154,7 @@ The field name. The type will be `DeepKeys<TParentData>` to ensure your name is
 
 #### Defined in
 
-[tanstack-field.directive.ts:41](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L41)
+[tanstack-field.directive.ts:42](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L42)
 
 ***
 
@@ -148,7 +166,7 @@ tanstackField: FormApi<TParentData, TFormValidator>;
 
 #### Defined in
 
-[tanstack-field.directive.ts:49](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L49)
+[tanstack-field.directive.ts:50](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L50)
 
 ***
 
@@ -164,7 +182,7 @@ optional unmount: () => void;
 
 #### Defined in
 
-[tanstack-field.directive.ts:73](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L73)
+[tanstack-field.directive.ts:78](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L78)
 
 ***
 
@@ -182,7 +200,7 @@ A validator provided by an extension, like `yupValidator` from `@tanstack/yup-fo
 
 #### Defined in
 
-[tanstack-field.directive.ts:48](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L48)
+[tanstack-field.directive.ts:49](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L49)
 
 ***
 
@@ -200,7 +218,7 @@ A list of validators to pass to the field
 
 #### Defined in
 
-[tanstack-field.directive.ts:53](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L53)
+[tanstack-field.directive.ts:54](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L54)
 
 ## Methods
 
@@ -225,7 +243,7 @@ children are checked.
 
 #### Defined in
 
-[tanstack-field.directive.ts:85](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L85)
+[tanstack-field.directive.ts:90](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L90)
 
 ***
 
@@ -248,7 +266,7 @@ before a directive, pipe, or service instance is destroyed.
 
 #### Defined in
 
-[tanstack-field.directive.ts:81](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L81)
+[tanstack-field.directive.ts:86](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L86)
 
 ***
 
@@ -274,4 +292,4 @@ It is invoked only once when the directive is instantiated.
 
 #### Defined in
 
-[tanstack-field.directive.ts:75](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L75)
+[tanstack-field.directive.ts:80](https://github.com/TanStack/form/blob/main/packages/angular-form/src/tanstack-field.directive.ts#L80)

docs/framework/react/guides/basic-concepts.md

@@ -195,6 +195,26 @@ const firstName = form.useStore((state) => state.values.firstName)
 
 Note: The usage of the `form.useField` hook to achieve reactivity is discouraged since it is designed to be used thoughtfully within the `form.Field` component. You might want to use `form.useStore` instead.
 
+## Listeners
+
+`@tanstack/react-form` allows you to react to specific triggers and "listen" to them to dispatch side effects.
+
+Example:
+
+```tsx
+<form.Field
+  name="country"
+  listeners={{
+    onChange: ({ value }) => {
+      console.log(`Country changed to: ${value}, resetting province`)
+      form.setFieldValue('province', '')
+    }
+  }}
+/>
+```
+
+More information can be found at [Listeners](./listeners.md)
+
 ## Array Fields
 
 Array fields allow you to manage a list of values within a form, such as a list of hobbies. You can create an array field using the `form.Field` component with the `mode="array"` prop.

docs/framework/react/guides/listeners.md

@@ -0,0 +1,67 @@
+---
+id: listeners
+title: Side effects for event triggers
+---
+
+For situations where you want to "affect" or "react" to triggers, there's the listener API. For example, if you, as the developer, want to reset a form field as a result of another field changing, you would use the listener API.
+
+Imagine the following user flow:
+
+- User selects a country from a drop-down.
+- User then selects a province from another drop-down.
+- User changes the selected country to a different one.
+
+In this example, when the user changes the country, the selected province needs to be reset as it's no longer valid. With the listener API, we can subscribe to the onChange event and dispatch a reset to the field "province" when the listener is fired.
+
+Events that can be "listened" to are:
+
+- onChange
+- onBlur
+- onMount
+- onSubmit
+
+```tsx
+function App() {
+  const form = useForm({
+    defaultValues: {
+      country: '',
+      province: '',
+    },
+    // ...
+  })
+
+  return (
+    <div>
+      <form.Field name="country">
+        {(field) => (
+          <label>
+            <div>Country</div>
+            <input
+              value={field.state.value}
+              onChange={(e) => field.handleChange(e.target.value)}
+              listeners={{
+                onChange: ({ value }) => {
+                  console.log(`Country changed to: ${value}, resetting province`)
+                  form.setFieldValue('province', '')
+                }
+              }}
+            />
+          </label>
+        )}
+      </form.Field>
+
+      <form.Field name="province">
+        {(field) => (
+          <label>
+            <div>Province</div>
+            <input
+              value={field.state.value}
+              onChange={(e) => field.handleChange(e.target.value)}
+            />
+          </label>
+        )}
+      </form.Field>
+    </div>
+  )
+}
+```

docs/framework/vue/guides/basic-concepts.md

@@ -228,6 +228,35 @@ const firstName = form.useStore((state) => state.values.firstName)
 </template>
 ```
 
+## Listeners
+
+`@tanstack/vue-form` allows you to react to specific triggers and "listen" to them to dispatch side effects.
+
+Example:
+
+```vue
+<template>
+    <form.Field
+      name="country"
+      :listeners="{
+        onChange: ({ value }) => {
+          console.log(`Country changed to: ${value}, resetting province`)
+          form.setFieldValue('province', '')
+        } 
+      }"
+    >
+      <template v-slot="{ field }">
+        <input
+          :value="field.state.value"
+          @input="(e) => field.handleChange(e.target.value)"
+        />
+      </template>
+    </form.Field>
+</template>
+```
+
+More information can be found at [Listeners](./listeners.md)
+
 Note: The usage of the `form.useField` method to achieve reactivity is discouraged since it is designed to be used thoughtfully within the `form.Field` component. You might want to use `form.useStore` instead.
 
 ## Array Fields