import { Meta } from "@storybook/addon-docs";

<Meta title="Component Library/Async Actions/In Forms/Documentation" />

# Async Actions In Forms

These directives should be used when building forms with buttons that trigger long running tasks in
the background, eg. Submit or Delete buttons. For buttons that are not associated with a form see
[Standalone Async Actions](?path=/story/component-library-async-actions-standalone-documentation--page).

There are two separately supported use-cases: Submit buttons and standalone form buttons (eg. Delete
buttons).

## Usage: Submit buttons

Adding async actions to submit buttons requires the following 3 steps

### 1. Add a handler to your `Component`

A handler is a function that returns a promise or an observable. Functions that return `void` are
also supported which is useful because `return;` can be used to abort an action.

**NOTE:** Defining the handlers as arrow-functions assigned to variables is mandatory if the handler
needs access to the parent component using the variable `this`.

**NOTE:** `formGroup.invalid` will always return `true` after the first `await` operation, event if
the form is not actually invalid. This is due to the form getting disabled by the `bitSubmit`
directive while waiting for the async action to complete.

**NOTE:** Handlers do not need to check if any previous requests have finished because the
directives have built in protection against users attempting to trigger new actions before the
previous ones have finished.

```ts
@Component({...})
class Component {
  formGroup = this.formBuilder.group({...});

  // submit can also return Observable instead of Promise
  submit = async () => {
    if (this.formGroup.invalid) {
      return;
    }

    await this.cryptoService.encrypt(/* ... */);

    // `formGroup.invalid` will always return `true` here

    await this.apiService.post(/* ... */);
  }
}
```

### 2. Add directive to the `form` element

Add the `bitSubmit` directive and supply the handler defined in step 1.

**NOTE:** The `directive` is defined using the input syntax: `[input]="handler"`. This is different
from how submit handlers are usually defined with the output syntax `(ngSubmit)="handler()"`.

**NOTE:** `[bitSubmit]` is used instead of `(ngSubmit)`. Using both is not supported.

```html
<form [formGroup]="formGroup" [bitSubmit]="submit">...</form>
```

### 3. Add directive to the `type="submit"` button

Add both `bitButton` and `bitFormButton` directives to the button.

**NOTE:** A summary of what each directive does can be found inside the source code.

```html
<button type="submit" bitButton bitFormButton>{{ "submit" | i18n }}</button>
```

## Usage: Standalone form buttons

Adding async actions to standalone form buttons requires the following 3 steps.

### 1. Add a handler to your `Component`

A handler is a function that returns a promise or an observable. Functions that return `void` are
also supported which is useful for aborting an action.

**NOTE:** Defining the handlers as arrow-functions assigned to variables is mandatory if the handler
needs access to the parent component using the variable `this`.

**NOTE:** Handlers do not need to check if any previous requests have finished because the
directives have built in protection against users attempting to trigger new actions before the
previous ones have finished.

```ts
@Component({...})
class Component {
  formGroup = this.formBuilder.group({...});

  submit = async () => {
    // contents of this handler are not relevant for this example
    // as this handler will not be trigger by standalone buttons using
    // `bitAction`
  }

  // action can also return Observable instead of Promise
  handler = async () => {
    await this.apiService.post(/* ... */);
  };
}
```

### 2. Add directive to the `form` element

The `bitSubmit` directive is required because of its coordinating role inside of a form.

```html
<form [formGroup]="formGroup" [bitSubmit]="submit">...</form>
```

### 3. Add directives to the `button` element

Add `bitButton`, `bitFormButton`, `bitAction` directives to the button. Make sure to supply a
handler.

**NOTE:** A summary of what each directive does can be found inside the source code.

```html
<button type="button" bitFormButton bitButton [bitAction]="handler">Do action</button>
<button type="button" bitFormButton bitIconButton="bwi-star" [bitAction]="handler"></button>
```

## `[bitSubmit]` Disabled Form Submit

If you need your form to be able to submit even when the form is disabled, then add
`[allowDisabledFormSubmit]="true"` to your `<form>`

```html
<form [formGroup]="formGroup" [bitSubmit]="submit" [allowDisabledFormSubmit]="true">...</form>
```
