wp-calypso/client/signup/README.md

# Modular Signup Framework

Modular Signup is a Calypso framework for creating flows that turn logged-out users without an account into logged-in users.

A Flow consists of a set of steps, organized in a certain order.

A Step is a React component that collects data for flows.

## Creating a new flow

You can define a new flow from `/client/signup/config/flows-pure.js`, by adding a new property to the `flows` array in the `generateFlows` function.

A flow is defined by two properties, `steps` and `destination`:

- `steps` is an array listing the steps in the flow, in the order they should be presented to users. You can see a list of available steps in `/client/signup/config/steps-pure.js`.
- `destination` is a `string` or `function` that determines which page users should be redirected to once they complete the last step in the flow. If provided as a `function`, it is called with all of the dependencies provided in the signup flow, and the user is redirected to whatever it returns.

There are also three optional properties:

- `description` is a brief description of what the flow is for.
- `lastModified` is a date stamp for when the flow was last updated.
- `disallowResume` is a boolean that, when true, will send you back to step 1 if you refreshed the page

Example:

```javascript
const account = { steps: [ 'site', 'user' ], destination: '/' };
```

Once you've added the flow to `flows-pure.js`, it'll be available for users at `/start/flow-name` where `flow-name` is the key of your flow in `flows`.

_Note:_ flows must include at least one step that creates a user and is able to provide a bearer token. See the `providesToken` property in "Creating a new step".

## Creating a new step

Anyone can create steps that flow designers can use in their flows.

You can add a new step to Modular Signup from `/client/signup/config/steps-pure.js`. A step is defined by a number of properties:

- `stepName` is the identifier used to reference a step in `/client/signup/config/flows-pure.js`.
- (optional) `dependencies`, which specify which properties this step needs from other steps in the flow in order to be processed.
- (optional) `providesDependencies` is an array that lets the signup framework know what dependencies the step is expected to provide. If the step does not provide all of these, or if it provides more than it says, an error will be thrown (unless `optionalDependencies` is used, see below).
- (optional) `optionalDependencies` is an array that lists which of the items in `providesDependencies` are optional. If one of these values is missing when a step is submitted there'll be no error.
- (optional) `delayApiRequestUntilComplete` is a boolean that, when true, causes the step's `apiRequestFunction` to be called only after the user has submitted every step in the signup flow. This is useful for steps that the user should be able to go back and change at any point in signup.
- (optional) `props` is an object with some custom properties that may be specific to a certain step.

You will also need to define which React component implements your step in `/client/signup/config/step-components.js`. Make sure to require the component as an internal dependency in `step-components.js`.

### Implementing a step

The React component for a step should be implemented in `/signup/steps/`, in its own directory.

Steps must use the `SignupActions` module, by requiring it as an internal dependency:

```javascript
import SignupActions from 'calypso/lib/signup/actions';
```

`SignupActions` allows the Modular Framework to handle the data collected by a step. This means your step must include a UI element that allows users to move to the next step in the flow, and that the function handling this element must use the method `submitSignupStep` from `SignupActions`.

In addition to `submitSignupStep`, make sure to also call `this.props.goToNextStep()` like in the example below. This allows the Modular Framework to render the next step in the flow. You will probably need to call `event.preventDefault()` as well, to skip the native handler for forms.

Example:

```javascript
function handleSubmit( event ) {
	event.preventDefault();

	SignupActions.submitSignupStep( {
		stepName: this.props.stepName,
	} );

	this.props.goToNextStep();
}
```

`submitSignupStep` takes the following parameters:

- a `step` object with the property `stepName`, the name of the step you're submitting.
- (optional) `providedDependencies`, an object describing the data added by the step to the Dependency Store. Use this only for data that does not come from API requests.
- (optional) `wasSkipped`, a flag indicating that an optional step was skipped when it is set to true.

Some background on `providedDependencies` and the Dependency Store: submitted steps are saved in the Progress Store, where they wait to have their dependencies met. For example, a step that creates a site needs to wait until a user account is created. Once that happens, the step is processed and its result is saved in the Dependency Store, so other steps can use it. You can read more about this [here](https://github.com/Automattic/wp-calypso/tree/HEAD/client/lib/signup).

### apiRequestFunction

If your step requires certain data from other steps before it can submit to the API, you can configure its `apiRequestFunction` in `signup/config/steps-pure.js`. This is a function that is called once the data the step requires is available.

```javascript
const object = {
	stepName: 'user-social',
	dependencies: [ 'siteSlug' ],
	apiRequestFunction: function ( callback, dependencies ) {
		wpcom.req.post( '/some-endpoint', dependencies.siteSlug, function ( errors, response ) {
			callback( errors, { userId: response.userId } );
		} );
	},
};
```

Note that here `apiRequestFunction` calls an API endpoint (`someRequest` in this example), from which they expect to get `userId`. If the API request is successful, `response.userId` is added to the Dependency Store via the callback. This is why you don't need to specify dependencies provided by API requests in `providedDependencies`.

`apiRequestFunction` also receives an object containing any dependencies listed in the `dependencies` property of the step in `/client/signup/config/steps-pure.js`. In the example above, the account step had a `dependencies` property set to `[ 'siteSlug' ]` and received the site slug in the `dependencies` argument of `apiRequestFunction` once it was called.

The above example includes an inline function definition, but we should keep the `apiRequestFunction` values in `StepActions` (`signup/config/step-actions.js`) and include them like:

```javascript
const step = {
	apiRequestFunction: stepActions.createSite,
};
```

## Hello World

The steps below guide you through creating a new flow and step:

1 - create a new directory in `/client/signup/steps` called `hello-world`.

2 - add an `index.jsx` file to this directory

3 - add a simple React component to `index.jsx`:

```jsx
export default function HelloWorld() {
	return <span>Hello world</span>;
}
```

4 - add the new step to `/client/signup/config/step-components.js`. Include a reference to the component module:

```javascript
const stepNameToModuleName = {
	'hello-world': 'hello-world-module-name', // Referencing signup/steps/hello-world-module-name/index.js
};
```

5 - add the new step to `/client/signup/config/steps-pure.js`. Include the component in the object returned from `generateSteps`:

```javascript
const steps = {
	'hello-world': {
		stepName: 'hello-world', // has to match the property name
	},
};
```

6 - add a new flow to `/client/signup/config/flow.js`:

```javascript
const flow = {
	hello: {
		// This will be the slug for the flow, i.e.: wordpress.com/start/hello
		steps: [ 'hello-world', 'user' ], // These are the steps that the user will be shown
		destination: '/', // This is where the user will be taken once the flow is complete
	},
};
```

7 - open <https://calypso.localhost:3000/start/hello> in an incognito window. You will be redirected to
the first step of the flow at `/start/hello/hello-world`, where you should see your new React component.

8 - now we need a way for users to move to the next step of the flow. Let's add a button and a form to the step's `render` method:

```jsx
function render() {
	return (
		<form onSubmit={ this.handleSubmit }>
			<p>This is the step named { this.props.stepName }</p>
			<button className="button" type="submit">
				Get started
			</button>
		</form>
	);
}
```

Make sure to require `SignupActions`:

```javascript
import SignupActions from 'calypso/lib/signup/actions';
```

... and to create a function to handle what happens when the form is submitted:

```javascript
handleSubmit = ( event ) => {
	event.preventDefault();

	SignupActions.submitSignupStep( {
		stepName: this.props.stepName,
	} );

	this.props.goToNextStep();
};
```

9 - open <https://calypso.localhost:3000/start/hello> in an incognito window. On opening you should be redirected to the first step showing your updated React component, and when you click the "Get started" button you should be taken to the next step.