Questions tagged [decorator]

The Decorator design pattern is a dynamic and object-oriented approach that enables the addition of behavior to pre-existing classes. This particular pattern falls under the structural design patterns introduced by the Gang of Four.

The custom class-validator decorator in NestJS fails to retrieve the value from the parameter

In my Nestjs project, I have created a Custom ValidatorConstraint using class-validator. The purpose is to create my own decorator and apply it later on DTO classes for validations. Let's consider this route: foo/:client After a request is made, I want t ...

Is there a possibility that typescript decorators' features will be polyfilled in browsers lacking ES5 support?

According to the typescript documentation, a warning is issued: WARNING If your script target is lower than ES5, the Property Descriptor will be undefined. If the method decorator returns a value, it will act as the Property Descriptor for the method. ...

angular typescript decorator

Testing the functionality of functions through unit testing with method decorators using mocha and sinon

I have a class method that looks like this: export class MyClass { @myDecorator() public async createItem(itemId: string, itemOptions: ItemOption[]): Promise<boolean> { // ... // return await create I ...

typescript unit-testing mocha.js decorator sinon

Utilizing Typescript Decorators to dynamically assign instance fields within a class for internal use

I am interested in delving into Typescript Decorators to enhance my coding skills. My primary objective is to emulate the functionality of @Slf4J from Project Lombok in Java using Typescript. The concept involves annotating/decorating a class with somethin ...

javascript typescript logging decorator lombok

The react decorator for maintaining type safety fails to identify the appropriate ReturnType of the supplied function

I want to enhance the redux connect feature by using it as a decorator for a specific reducer/state. Although I know that redux connect can already be used as a decorator, I am curious about why my custom implementation does not work the way I expect. Her ...

reactjs typescript decorator

Debug errors occur when binding to computed getters in Angular 2

Currently, I am integrating Angular 2 with lodash in my project. Within my model, I have Relations and a specific getter implemented as follows: get relationsPerType() { return _(this.Relations) .groupBy(p => p.Type) .toPairs() ...

javascript typescript angular decorator lodash

Ways to add up only the numerical digits in a given list by utilizing the decorate method

While attempting to pass a list to the function for summing numbers in a list, I encountered an error 'unsupported operand type(s) for +=: 'int' and 'str''. As a workaround, I decided to create a nettoyage function to filter out non-digit elements from the ...

python function decorator

Conditions are in an angular type provider with AOT

I am facing an issue with my Angular project that is compiled using AOT. I am trying to dynamically register a ClassProvider based on certain configurations. The simplified code snippet I am currently using is below: const isMock = Math.random() > 0.5; ...

javascript angular typescript decorator angular2-aot

Unlock the Power of Angular with Custom Decorators: Accessing ElementRef Made Easy

I am currently working on implementing a decorator for Host CSS Variable Binding in Angular5. However, I am facing difficulties in properly implementing it with the given code. Is there a way to define ElementRef from within the decorator itself? export f ...

angular typescript decorator

Understanding the significance of emitDecoratorMetadata in transpiled code

I have a question regarding the significance of the emitDecoratorMetadata option when transpiling TypeScript to JavaScript in an Angular 2 environment. If this option is set to false, and metadata is not included in the final code, what impact will it ha ...

angular typescript decorator

Can one mimic a TypeScript decorator?

Assuming I have a method decorator like this: class Service { @LogCall() doSomething() { return 1 + 1; } } Is there a way to simulate mocking the @LogCall decorator in unit tests, either by preventing it from being applied or by a ...

angular unit-testing typescript mocking decorator

'This' loses its value within a function once the decorator is applied

Scenario: Exploring the creation of a decorator to implement an interceptor for formatting output. Issue at Hand: Encountering 'this' becoming undefined post application of the decorator. // custom decorator function UseAfter(this: any, fn: (...args: any ...

typescript decorator

Is it feasible to access a service instance within a parameter decorator in nest.js?

I am looking to replicate the functionality of Spring framework in nest.js with a similar code snippet like this: @Controller('/test') class TestController { @Get() get(@Principal() principal: Principal) { } } After spending countless hours going ...

javascript node.js typescript decorator nestjs

What is the reason behind decorators needing to utilize apply(this) on a function?

I've been delving into the realm of JavaScript and exploring decorator code. One thing I've noticed is that when looking at decorator code like the example below, the input function always applies to 'this' even though it doesn't actually reference 'this ...

javascript typescript this decorator

Exploring how to read class decorator files in a Node.js environment

I've developed a custom class decorator that extracts permissions for an Angular component. decorator.ts function extractPermissions(obj: { [key: 'read' | 'write' | 'update' | 'delete']: string }[]) { return (ctor: Function) => { console ...

javascript node.js angular typescript decorator

How can I use the target type (and maybe even the property type) as a type parameter within a decorator?

In the process of incorporating a deep-watch property decorator in Angular, the following usage has been implemented: @Component({ /* ... */ }) export class AppComp { @Watch( 'a.b.c', function (last, current, firstChange) { // ca ...

angular typescript decorator

During the transpiling process, the metadata of an Angular component may become lost

Encountering another error: Uncaught Error: Unexpected value 'UserDialogComponent' declared by the module 'AppModule'. Please add a @Pipe/@Directive/@Component annotation. Current behavior Summary: When incorporating an external library that utilizes ref ...

angular typescript decorator angular2-decorators

Debugging with PHP Decorators

After reading an informative article and going through the Decorator example, I encountered an issue. The code is displaying <strong></strong> instead of the expected <strong><a href="logout.php">Logout</a></strong>. cl ...

php oop design-patterns decorator

Steps to apply a decorator to a function that is not a nestjs route

NestJS Hello there! I am currently facing an issue where I need to apply a decorator to a function that is not serving as an endpoint or route. To illustrate, here is what I have in mind: class Controller { @Get('/') firstMethod() { secon ...

typescript nestjs decorator

Is it possible to create an instance in TypeScript without using class decorators?

As per the definition on Wikipedia, the decorator pattern enables you to enhance an object of a class with additional functionalities, such as: let ball = new BouncyBall(new Ball()) The Ball object is adorned with extra features from the BouncyBall class ...

typescript oop decorator

Arrow functions do not function properly with Typescript decorators

I've created a typescript decorator factory that logs the total time taken to execute a function, along with the actual function execution results and parameters passed to the decorator. For example: export function performanceLog(...args: any[]) { retur ...

javascript typescript ecmascript-6 decorator typescript-decorator

How to utilize method decorators effectively in C# programming

One interesting feature in python is the ability to use function decorators to enhance the functionality of functions and methods. Currently, I'm in the process of transitioning a device library from python to C#. During communication with the device ...

c#python design-patterns decorator

Is it possible to make a property subscriptable when aliasing two dictionaries using the property decorator?

My preference is for c to equal a + b. class A: def __init__(self, a, b): self.a = a self.b = b @property def c(self): return self.b + self.a @c.setter def c(self, value): self.b = value - self.a ...

python dictionary properties decorator getter-setter

What is the process for triggering property decorators during runtime?

Wondering about dynamically invoking a property decorator at runtime. If we take a look at the code snippet below: function PropertyDecorator( target: Object, // The prototype of the class propertyKey: string | symbol // The name of th ...

javascript typescript annotations decorator

Accurate test counting with the help of decorators for providing unit testing data

I implement a unique method of passing data to my Python unit tests using a function decorator and data-provider-functions. My approach is quite similar to the one demonstrated by this individual. Everything functions smoothly except for one minor, yet bot ...

python unit-testing decorator

Eliminating Angular's @Injectable decorator in npm build process

I have encountered a setback while working on a small helper package for Angular. The issue I am facing is related to an exported class that serves as an Angular service and is decorated with @Injectable(). After running npm run build, the compiled class ...

angular npm package decorator typescript-decorator

Newtab Q&A