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How To Use The PortalsPlugin

The PortalsPlugin provides useful features to aid in communication between your Web and Native applications. It is included in the Ionic Portals library by default and takes advantage of the Capacitor Plugin system.

Setup#

Android and iOS#

Follow the Getting Started Guide to install the Ionic Portals library into your native mobile projects. The PortalsPlugin is automatically added to every instance of a Portal.

Web#

Install the Ionic Portals package from NPM into your web application.

npm install @ionic/portals

Initial Context#

The Initial Context mechanism allows you to pass data to your web application from native so that it is available for when the web application initially loads.

Setting Initial Context#

Initial context data can be set in two different ways. You may want to set it when building a new Portal using PortalManager.

PortalManager.newPortal("maps")    .setStartDir("web")    .setInitialContext(["ic_example": "hello world"])    .create()

You can also set Initial Context data on a Portal object prior to the Portal loading.

let portal = try! PortalManager.getPortal("maps")portal.initialContext = ["ic_example": "hello world"]

Using Initial Context#

To access the initial context from the PortalsPlugin class in your web application, import Portals and use the Portals.getInitialContext() function.

Portals.getInitialContext<{ ic_example: string; }>().then(context => {    // prints "hello world" in this example    console.log(context.value.ic_example)})

Initial context is useful when using a Single Page Application (SPA) across multiple Portals in your application. The route to a specific section of the SPA can be passed in as initial context data. Your web application can then use it to load that section directly without need for a redirect. Check out our how-to guide.

Communicating via Pub/Sub#

The Publish and Subscribe mechanism (pub/sub) built into the PortalsPlugin allows you to send data between your web and native applications through a Portal.

Defining Subscribers#

Subscribers listen for messages sent to a certain topic. They can be defined in your web application to listen for messages published from native, and vice versa.

To listen for a message published from the native side of a Portal, define a subscriber in your web application.

const portalSubscription = await Portals.subscribe(      { topic }, (result) => {        console.log(JSON.stringify(result))      });

To listen for messages published from the web side of a Portal, define a subscriber in your native application.

MyViewController.swift
override func viewDidLoad() {    let portal = try! PortalManager.getPortal("example")        // ...        // listen on the topic "dismiss" and define a function `dismiss`     // to handle messages    self.subscriptionRef = PortalsPlugin.subscribe("dismiss", dismiss)        super.viewDidLoad()}    /** * An example function that dismisses the view when a dismiss * message is received */func dismiss(result: SubscriptionResult) {    if(result.data as! String == "cancel" || result.data as! String == "success") {        DispatchQueue.main.async {            self.dismiss(animated: true, completion: nil)        }    }}

Android: Subscribe Using Annotations#

Android also provides a way to link subscribers defined as methods with annotations.

override fun onCreate(savedInstanceState: Bundle?) {    super.onCreate(savedInstanceState)        // ...
    val portal = PortalManager.getPortal("example")    val portalFragment = PortalFragment(portal)
    // register this class as having defined message subscribers    portalFragment!!.linkMessageReceivers(this)
    // ...
    // add the PortalFragment to the example container fragment    val fragmentManager = childFragmentManager    fragmentManager.beginTransaction().replace(R.id.example_web_app, portalFragment!!).commit()}
/** * Define a `dismiss` method to receive messages on the "dismiss"  * topic and act on the message. This is an example to dismiss  * a containing native DialogFragment. */@PortalMethodfun dismiss(result: String?) {    if (result != null && (result == "cancel" || result == "success")) {        this.dismiss()    }}

Publishing Messages#

Publish messages to send data through a Portal to registered Subscribers.

From Web to iOS/Android#

To send a message from your web application to iOS or Android, use the Portals.publish() function.

Portals.publish({ topic: 'dismiss', data: 'success' })

From iOS/Android to Web#

To send messages from your native application to the web application, use the PortalsPlugin.publish() methods.

PortalsPlugin.publish("weather", "sunny")

Examples#

The PortalsPlugin is used in the E-Commerce App demo.