subscription | 易学教程

Angular - two subscriptions in ngOnInit result in object 'undefined'

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问题 In short.. I am not able to access my news object. It is coming back as 'undefined' when called in a function. In my ngOnInit I have two subscriptions. First one returns a news object (which is defined as a global variable at the top of the component). The second subscription returns a route parameter and then triggers a function (navigateToArticle). Now... when the second subscription triggers the 'navigateToArticle' function, I want that function to be able to access the news object.

How to ensure an event is only subscribed to once

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I would like to ensure that I only subscribe once in a particular class for an event on an instance. For example I would like to be able to do the following: if (*not already subscribed*) { member.Event += new MemeberClass.Delegate(handler); } How would I go about implementing such a guard? Hamish Smith If you are talking about an event on a class that you have access to the source for then you could place the guard in the event definition. private bool _eventHasSubscribers = false; private EventHandler<MyDelegateType> _myEvent; public event EventHandler<MyDelegateType> MyEvent { add { if (

Adding a custom field to Magento's subscription module

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问题 The newsletter subscription module in Magento has only one field (email) by default. After I add an extra field to the form (say country), how can I get the form data to show up in the Magento back-end and be sent as an email to a preset recipient? Thanks. 回答1: There are a few things that you need to take care of to make this work: Add a new column for your data to the appropriate database table Make sure that magento saves your new field to the database Present the data in the admin backend

Am I getting the steps right for verifying a user's Android in-app subscription?

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问题 I am making an app that does not require a user account/login, and allows the user to purchase a subscription. I want to use the Google Play Developer API to verify whether or not a user has a purchased/active subscription. From all of the documentation, I\'ve gathered the following steps. Are they correct, and could you answer the two questions in them? Create a Service Account in the Google APIs Console. Save the private key that is given to me (where? surely not in my code/on the device as

Unable to get the subscription information from Google Play Android Developer API

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I'trying to use Google APIs Client Library for Java to get information about user's subscriptions purchased in my android app. Here is how I'm doing for now: HttpTransport HTTP_TRANSPORT = new NetHttpTransport(); JsonFactory JSON_FACTORY = new JacksonFactory(); GoogleCredential credential = new GoogleCredential.Builder().setTransport(HTTP_TRANSPORT) .setJsonFactory(JSON_FACTORY) .setServiceAccountId(GOOGLE_CLIENT_MAIL) .setServiceAccountScopes("https://www.googleapis.com/auth/androidpublisher") .setServiceAccountPrivateKeyFromP12File(new File(GOOGLE_KEY_FILE_PATH)) .build(); Androidpublisher

How to ensure an event is only subscribed to once

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问题 I would like to ensure that I only subscribe once in a particular class for an event on an instance. For example I would like to be able to do the following: if (*not already subscribed*) { member.Event += new MemeberClass.Delegate(handler); } How would I go about implementing such a guard? 回答1: If you are talking about an event on a class that you have access to the source for then you could place the guard in the event definition. private bool _eventHasSubscribers = false; private

Unable to get the subscription information from Google Play Android Developer API

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问题 I\'trying to use Google APIs Client Library for Java to get information about user\'s subscriptions purchased in my android app. Here is how I\'m doing for now: HttpTransport HTTP_TRANSPORT = new NetHttpTransport(); JsonFactory JSON_FACTORY = new JacksonFactory(); GoogleCredential credential = new GoogleCredential.Builder().setTransport(HTTP_TRANSPORT) .setJsonFactory(JSON_FACTORY) .setServiceAccountId(GOOGLE_CLIENT_MAIL) .setServiceAccountScopes(\"https://www.googleapis.com/auth

Angular/RxJs When should I unsubscribe from `Subscription`

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问题 When should I store the Subscription instances and invoke unsubscribe() during the NgOnDestroy life cycle and when can I simply ignore them? Saving all subscriptions introduces a lot of mess into component code. HTTP Client Guide ignore subscriptions like this: getHeroes() { this.heroService.getHeroes() .subscribe( heroes => this.heroes = heroes, error => this.errorMessage = <any>error); } In the same time Route & Navigation Guide says that: Eventually, we\'ll navigate somewhere else. The