I have one class ContentManager on android objects and global variables ContentManager style, the aim is to create this object from one time only, you can get set properties for it anywhere in the app, now declared on React native the declaration is this? the picture below is me java code on android. Help!!!!!!!
code in java
code in java
create global.js
module.exports = {
// your global variable
},
};
Then require it at the top in your file
GLOBAL = require('../global');
for access
GLOBAL.your_variable_name
Related
I am experiencing the dreaded not an "own property" of its parent issue when attempting to build my Handlebars project.
I have been down the rabbit hole and seen the many explanations of using #handlebars/allow-prototype-access to allow the issue to be bypassed, however it seems the project does not use a standard implementation of Handlebars...
It seems I am using something called engine-handlebars
Where I would expect to implement that allow-prototype-access change, I see the following:
app.pages('./source/pages/**/*.hbs');
app.engine('hbi', require('engine-handlebars'));
I can't fathom how I am supposed to implement the prototype access with this setup...
It seems, after a bit of trial and error, commenting lines out as I go, that the line app.pages('./source/pages/**/*.hbs'); is actually causing the issue...
When I run the project with this line in, I get the error:
Handlebars: Access has been denied to resolve the property "path" because it is not an "own property" of its parent.
You can add a runtime option to disable the check or this warning:
See https://handlebarsjs.com/api-reference/runtime-options.html#options-to-control-prototype-access for details
[10:54:49] ERROR - undefined: Cannot read property 'substring' of undefined
The plugin #handlebars/allow-prototype-access works by modifying the Handlebars instance.
const _Handlebars = require('handlebars');
const { allowInsecurePrototypeAccess } = require('#handlebars/allow-prototype-access');
const Handlebars = allowInsecurePrototypeAccess(_Handlebars);
Note that allowInsecurePrototypeAccess does not modify the instance in place, but creates an isolated instance via Handlebars.create() so you must use its return value.
In your case, engine-handlebars exposes the Handlebars instance in different ways depending on what version you are using.
Based on your code you provided, my guess is you are using <1.0.0, but I'll provide methods for adjusting this for all its versions.
engine-handlebars#<0.6.0
Unfortunately these versions don't expose Handlebars in any way, so if you are using this version I recommend upgrading engine-handlebars to a later version.
engine-handlebars#>=0.6.0 <1.0.0
Version 0.6.0 exposed Handlebars as a property on the exported engine function. This is then referenced throughout the library via this.Handlebars.
You can then change this before setting the app.engine() and it should work.
const _Handlebars = require('handlebars');
const { allowInsecurePrototypeAccess } = require('#handlebars/allow-prototype-access');
const engine = require('engine-handlebars');
// elsewhere...
// const app = ...
// Do this *before* setting app.engine
const insecureHandlebars = allowInsecurePrototypeAccess(_Handlebars);
engine.Handlebars = insecureHandlebars;
app.engine('hbi', engine);
engine-handlebars#>=1.0.0
For version 1.0.0 and beyond, you must pass the Handlebars instance yourself.
const Handlebars = require('handlebars');
const engine = require('engine-handlebars')(Handlebars);
Thus you don't need to set anything on engine, you just pass in the modified instance when you need it.
const _Handlebars = require('handlebars');
const { allowInsecurePrototypeAccess } = require('#handlebars/allow-prototype-access');
// elsewhere...
// const app = ...
// Do this *before* setting app.engine
const insecureHandlebars = allowInsecurePrototypeAccess(_Handlebars);
const engine = require('engine-handlebars')(insecureHandlebars);
app.engine('hbi', engine);
I'd like to preference this by saying my backgrounds in in C# so I like declaring methods within my classes. I've created a user class that contains properties and methods and I've added this to my vuex-persistedstate. One of the methods is a logout() method which clears out the properties. When I tried to invoke this method I got the following error:
TypeError: this.$data.user.logout is not a function
I then reviewed local storage and noted the user did not have reference to the class method. So I went ahead and copied the logic from the method into my vue component and it worked so I'm assuming the issue is vuex-persistedstate does not save references to methods which is why the method call did not work.
I'd like to declare the logout method in one location rather than spreading it out across vue components, what is the best practice for accomplishing this? Is it possible to do this in the class declaration or do I need a user helper file?
Sure Berco! My code is also up on GitHub so you can review it there too, but basically it seems to me that vuex does not store methods. The first file you should review is my user.js file:
https://github.com/Joseph-Anthony-King/SudokuCollective/blob/master/SudokuCollective.WebApi/client/src/models/user.js
In this file I have a method called shallow clone which takes the info received from the API and assigns it to the user:
shallowClone(data) {
if (data !== undefined) {
this.id = data.id;
this.userName = data.userName;
this.firstName = data.firstName;
this.lastName = data.lastName;
this.nickName = data.nickName;
this.fullName = data.fullName;
this.email = data.email;
this.isActive = data.isActive;
this.isAdmin = data.isAdmin
this.isSuperUser = data.isSuperUser;
this.dateCreated = data.dateCreated;
this.dateUpdated = data.dateUpdated;
this.isLoggedIn = data.isLoggedIn;
}
}
You of course don't need to abstract this away but I've found it makes the code easier to maintain.
Then in the mounted() lifecycle hook I assign the user received from the API to the component user via the shallowClone method. Please bear in mind I've done additional work on this project and the login form is now it's own component which receives the user as a prop from the app:
https://github.com/Joseph-Anthony-King/SudokuCollective/blob/master/SudokuCollective.WebApi/client/src/components/LoginForm.vue
mounted() {
let self = this;
window.addEventListener("keyup", function (event) {
if (event.keyCode === 13) {
self.authenticate();
}
});
this.$data.user = new User();
this.$data.user.shallowClone(this.$props.userForAuthentication);
},
The full code can be reviewed here:
https://github.com/Joseph-Anthony-King/SudokuCollective
I found a solution... I'm working on improving it. Basically I use the values pulled from localstorage into vuex to create a new user object in the vue component that has reference to the methods located in my user class declaration. I recalled recommendations that we should create clones of objects pulled from vuex for use within the vue component. I'm still refining the code but that's basic idea.
I'm reading the Vue.js guide, and I've come across the statement.
Template expressions are sandboxed and only have access to a whitelist
of globals such as Math and Date. You should not attempt to access
user defined globals in template expressions.
What are all the globals available in templates?
That is, what is the content of the whitelist, exhaustively?
Vue.js defines the whitelist of globals in the core/instance/proxy.js file:
//...
const allowedGlobals = makeMap(
'Infinity,undefined,NaN,isFinite,isNaN,' +
'parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,' +
'Math,Number,Date,Array,Object,Boolean,String,RegExp,Map,Set,JSON,Intl,' +
'require' // for Webpack/Browserify
)
// ...
When Vue compiles the template, the string interpolations are processed, and if you reference a global that is not whitelisted, you will have a warning on Development.
If you are curious about how templates are compiled to render functions, look through the template explorer.
From what I understood from source code globals are declared in a variable and make it available via a proxy between vm instance and template :
const allowedGlobals = makeMap(
'Infinity,undefined,NaN,isFinite,isNaN,' +
'parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,' +
'Math,Number,Date,Array,Object,Boolean,String,RegExp,Map,Set,JSON,Intl,' +
'require' // for Webpack/Browserify
)
So gobals available in template are :
Infinity
undefined
NaN
isFinite
isNaN
parseFloat
parseInt
decodeURI
decodeURIComponent
encodeURI
encodeURIComponent
Math
Number
Date
Array
Object
Boolean
String
RegExp
Map
Set
JSON
Intl
require
If you try to put in your template a reference that is not whitelisted or not in your vm instance then you will have this warning :
Property or method "${key}" is not defined on the instance but
referenced during render. Make sure that this property is reactive
either in the data option, or for class-based components, by
initializing the property.
I'm interested in wrapping some C++ libraries as react-native modules but I'm hitting a bit of a conceptual wall. Very new to this stuff so bear with me!
I want to wrap something like the AudioProcessorGraph functionality of Juce https://juce.com/doc/classAudioProcessorGraph_1_1AudioGraphIOProcessor
However a big component of the api is connecting audio node objects to each other to form an audio processing graph. You can imagine something very similar to the web audio api:
const audioCtx = new AudioContext();
const oscillator = new OscillatorNode(audioCtx);
const gainNode = new GainNode(audioCtx);
oscillator.connect(gainNode).connect(audioCtx.destination);
The problem I'm seeing, before I even write a single line of code, is that I don't see a way with the RCT_EXPORT_METHOD macro to pass an instance of a native object as an argument to a method call of another native object. https://nodejs.org/api/addons.html#addons_wrapping_c_objects I've done similar things with native node addons using the ObjectWrap functionality. Is there anyway to accomplish something similar with react-native?
RCT_EXPORT_METHOD is used to export a function to the JS side in IOS. The caveat here is that the arguments you pass via JS to Native or from Native to JS should be serializable. This is because the communication happens via the RN Bridge in async manner.
This is what I would do in your case. Lets take the example:
Lets say you have a function in native module
//Initialise a list to store audioContexts
ArrayList<AudioContext> audioCtxList = new ArrayList<AudioContext>();
#ReactMethod
public void createAudioContext(Callback cb){
AudioContext audioCtx = new AudioContext();
audioCtxList.add(audioCtx);
cb.invoke(//...index of the newly created audioCtx)
}
Now in the JS side you have a reference that u can use to talk to native module
so next function would look something like
#ReactMethod
public void createOscillator(int audioCtxId){
AudioCtx actx = // Get the audioContext from the list using the audioCtxId
const oscillator = new OscillatorNode(audioCtx);
const gainNode = new GainNode(audioCtx);
oscillator.connect(gainNode).connect(audioCtx.destination);
}
As a result you would not need to export any native object to JS side and you can accomplish the functionality u need too.
I'm using TypeScript and require.js to resolve dependencies in my files. I'm in a situation where I want to reference a static field of a class in an other file, but in the same internal module (same folder) and I am not able to access it, even if the Visual Studio pre-compiler does not show any error in my code.
I have the following situation :
Game.ts
class Game {
// ...
static width: number = 1920;
// ...
}
export = Game;
Launcher.ts
/// <reference path='lib/require.d.ts'/>
import Game = require("Game");
var width: number = Game.width;
console.log(width); // Hoping to see "1920"
And the TypeScript compiler is ok with all of this. However, I keep getting "undefined" at execution when running the compiled Launcher.ts.
It's the only reference problem I'm having in my project, so I guess the rest is configured correctly.
I hope I provided all necessary information, if you need more, please ask
Any help is appreciated, thanks !
Your code seems sound, so check the following...
You are referencing require.js in a script tag on your page, pointing at Launcher (assuming Launcher.ts is in the root directory - adjust as needed:
<script src="Scripts/require.js" data-main="Launcher"></script>
Remove the reference comment from Launcher.ts:
import Game = require("Game");
var width: number = Game.width;
console.log(width); // Hoping to see "1920"
Check that you are compiling using --module amd to ensure it generates the correct module-loading code (your JavaScript output will look like this...)
define(["require", "exports", "Game"], function (require, exports, Game) {
var width = Game.width;
console.log(width); // Hoping to see "1920"
});
If you are using Visual Studio, you can set this in Project > Properties > TypeScript Build > Module Kind (AMD)
If you are using require.js to load the (external) modules, the Game class must be exported:
export class Game {}
If you import Game in Launcher.ts like
import MyGame = require('Game')
the class can be referenced with MyGame.Game and the static variable with MyGame.Game.width
You should compile the ts files with tsc using option --module amd or the equivalent option in Visual Studio