I'm hiding tabs in Ionic 2 for certain @Pages (an Ionic 2 decorator) using a simple TabsProvider:
tabs.ts
import { Injectable } from 'angular2/core';
import { BehaviorSubject } from 'rxjs';
@Injectable()
export class TabsProvider {
currentState = new BehaviorSubject<boolean>(true);
public showTabs(){
this.currentState.next(true);
}
public hideTabs(){
this.currentState.next(false);
}
}
The tabs component subscribes to currentState, and TabsProvider is injected into various pages as below:
sample-page.ts:
import {Page} from 'ionic-angular';
import { TabsProvider } from './tabs';
@Page({
...
})
export class SamplePage {
tabsProvider: TabsProvider;
constructor(tabsProvider: TabsProvider) {
this.tabsProvider = tabsProvider;
}
onPageWillEnter(){
this.tabsProvider.hideTabs();
}
onPageWillLeave(){
this.tabsProvider.showTabs();
}
}
This code is practically all boilerplate, and would be much cleaner if I could define this functionality in a decorator (or annotation), e.g.:
import { Page } from 'ionic-angular';
import { hideTabs } from './tabs';
@hideTabs()
@Page({
...
})
export class BuyPage {
}
But I'm having trouble determining how to inject TabsProvider and add the onPageWillEnter and onPageWillLeave methods to SamplePage.
The farthest I've gotten so far:
in tabs.ts:
export function hideTabs() {
return function(cls: any) {
cls.prototype.onPageWillEnter = function() {
this.tabsProvider.hideTabs();
};
cls.prototype.onPageWillLeave = function() {
this.tabsProvider.showTabs();
};
return cls;
}
}
This gets us part of what we're looking for, but it's still necessary to import and inject TabsProvider as a specific instance member:
sample-page.ts
import {Page, Events} from 'ionic-angular';
import { hideTabs, TabsProvider } from './tabs';
@hideTabs()
@Page({
...
})
export class SamplePage {
constructor(public tabsProvider: TabsProvider) {
}
}
@hideTabs()?Relevant parts of the tabs component (for anyone interested in implementing) pages/tabs/tabs.ts:
import { Page } from 'ionic-angular';
import { TabsProvider } from './tabs';
@Page({
...
})
export class TabsPage {
...
currentState: boolean;
constructor(TabsProvider: TabsProvider) {
TabsProvider.currentState.subscribe((state: boolean) => {
this.currentState = state;
});
}
}
pages/tabs/tabs.html:
<div [ngClass]="{'hide-tabs': !currentState}">
<ion-tabs>
...
</ion-tabs>
</div>
pages/tabs/tabs.scss:
.hide-tabs ion-tabbar-section {
display: none;
}
I have just had the same problem, and this is the solution I came up with. The general approach is to:
Reflect.getOwnMetadata to read the existing dependencies from the class.tabs.ts:
import TabsProvider from "./tabs";
export function hideTabs() {
return function(cls: Function) : any {
// Save existing onPageWillEnter and onPageWillLeave inplementations
let enter = cls.prototype.onPageWillEnter || function () {};
let leave = cls.prototype.onPageWillLeave || function () {};
// Create new constructor for class
const newCls = function (tabsProvider, ...args) {
this.__hideTabs__tabsProvider = tabsProvider;
return cls.apply(this, args);
}
// Copy prototype to new constructor
newCls.prototype = constructor.prototype;
// Copy metadata to new constructor
let metadatakeys = Reflect.getMetadataKeys(cls);
metadatakeys.forEach(function (key) {
Reflect.defineMetadata(key, Reflect.getOwnMetadata(key, cls), newCls)
});
// Read dependencies list from 'cls', add our own dependency, and write list to 'newCls'
let dependencies = Reflect.getOwnMetadata('design:paramtypes', cls);
dependencies = [TabsProvider].concat(dependencies)
Reflect.defineMetadata('design:paramtypes', params, newCls);
// Define new onPageWillEnter and onPageWillLeave implementation which implement tab show/hide functionality
// and also call the old implementation saved above (if they exist)
newCls.prototype.onPageWillEnter = function() {
this.tabsProvider.hideTabs();
enter.apply(this, arguments);
};
newCls.prototype.onPageWillLeave = function() {
this.tabsProvider.showTabs();
leave.apply(this, arguments);
};
return newCls;
}
}
I would also recommend moving the @hideTabs decorator below the @Page decorator
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