跟讀練習: Every NestJS Concept Explained in 9 Minutes - 通過影片學習英語口語

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I know exactly which button to press on my microwave to heat up my food, but if it breaks, I wouldn't be able to fix it.

So the same goes for programming.

So have you ever wondered how some people seem to always know how to fix the code, where to find the relevant information, and how to best implement new features?

They don't actually know everything.

They just understand the key concepts and principles that allow them to navigate any piece of code they encounter.

And after countless hours of going through the NestJS documentation, I've condensed the entire framework into 10 core concepts.

And by the end of this video, I'm fairly confident that you too will be able to understand any NestJS code you encounter.

The first concept is not often talked about, but it's actually a key to understand what NestJS is and what you can build with it.

So there is a misconception that NestJS is only for building APIs.

but in fact, there are three types of applications you can build with Nest.

You can create HTTP server using the Nest Factory Create and request endpoints and effectively create APIs and web servers.

But you can also create microservices applications using Nest Factory Create Microservice.

And microservices are very similar to HTTP servers, except that they can use different transport protocol such as TCP or NAT, and they can communicate via an internal network.

And last but not least, you can also create standalone applications using Nest Factory Create Application Context.

And a standalone application is just an application that doesn't have network listener.

So they are great for creating scheduled tasks or creating CLI tools even if you want.

But they all have one thing in common.

They need a root module.

So let's talk about modules now.

Modules are the building blocks of a Nest application.

So you can picture a Nest app as a graph made of modules.

And at the top, you always have a root module, and that root module can use other modules, and those modules can themselves use other modules and so on.

For example, you could have an application with a product module, an order module that uses a cart and payment module, and they could all be using a shared configuration module.

In terms of the implementation, a module is a class that is annotated with a module decorator.

And you absolutely need to understand the concept of decorators because they are everywhere in NestJS.

Decorators can be a bit strange to start with, but once you understand what they are, it all clicks and you can do really powerful things.

So a decorator is a special kind of function and it can be attached to methods, classes, properties, and it modifies their behavior and it can even add metadata.

Think of decorators as wearing accessories or suits that give you extra power.

For example, you can take an empty naked class and dress it with a fancy shiny module decorator suit.

And that means that it can be used by other classes that are wearing the same shiny module decorator suit.

To create the application module graph, you define relationship between modules by passing an object property to the module decorators.

And you define the related modules in the import property.

And once you have modules, you can add controllers inside them.

Controllers are classes that are annotated with the controller decorator.

So let's say that they are wearing a blue jacket.

So a controller is simply in charge of receiving incoming requests and returning a response.

So you can define a root path in the controller decorator, and you add methods to handle the incoming request.

and those methods can be annotated with a HTTP verb and those decorators can take a sub root as parameter.

So the main role of the controller is to receive requests and return response.

Anything else is delegated to other classes.

Most of the code that you will be writing in Nest is within providers.

So a provider is simply a class that can be injected in other classes as dependency.

So let's take a user service class as an example.

So you annotate that class with the injectable decorator to indicate that it's a provider.

Then you declare it as a provider in the user's module.

And now you can inject it in the controller via the constructor so you can think of providers as

freelance workers and nest.js is an agency that places those freelance workers wherever they are needed and congratulations you've

used dependency injection and the singleton pattern now let me show you how to take full control of the request handling flow starting wheel middlewares.

When you want to take a plane, you don't just park on the tarmac and enter the plane.

So you have to go to check in your luggage, then you go through security, then you might even go through border control, then you show your boarding pass, and finally you get on the plane.

So just like a plane passenger, you can make a request go through several stages before it's handed over to the method handler.

So for example, you could use middleware to log every incoming requests.

But don't start adding middlewares everywhere because I'll show you in the next concept that Nest comes with built-in features for common request flow management.

Guards are a critical part of the request lifecycle in NestJS.

So they work more or less like security check at an airport and their primary purpose is to determine whether the request will be handled by the root handler based on specific conditions like roles, permissions, or any custom logic.

So they They have access to the execution context, and that allows them to inspect some details about the request.

For example, an authentication guard can check if the user is authenticated and authorized to access a requested resource.

And if the guard returns true, then the request passes through.

And if it returns false, then the request is denied, and we'd send an error response to the client, for example.

After the guard, you can add interceptors to your application.

So they run before and after the root handler.

So they give you full control over the request response cycle.

So interceptors implement the nest interceptor interface and they can perform tasks like logging or caching.

For example, an interceptor can log request details or map the response and input data format.

The next stop before getting to the handler is pipes.

So that's where you can validate and transform the data that is handed to the handler to ensure that it meets certain criteria or is in the correct format.

So pipes are classes that implement the pipe transform interface and they are annotated with the injectable decorator.

So for instance, a pipe can validate the data sent in the request to ensure that it conforms with the expected format or the expected type or certain constraints.

It's up to you to implement whatever validation rules you want.

But if the data is invalid, then the pipe can throw an exception, preventing the root handler from executing.

Additionally, pipes can transform the data into a more suitable format for processing.

For example, a pipe can convert a string input into integer or parse dates from string representations.

So built-in pipes like validation pipe, parsing pipe, and parse UUID offer some common validation and transformation.

but you can also create custom pipes to handle specific requirements.

If at any point during the request handling, there is an unhandled error, Nest.js would return a 500 internal error by default.

But you can manually throw standard HTTP exceptions as well and be a bit more descriptive.

And you can even customize error handling through exception filters.

Exception filters are classes that implement the exception filter interface and they are decorated with the catch decorator.

They can catch exceptions thrown by any part of the request handling process, including guards, interceptors, pipes, or root handlers, of course.

But when an exception is caught, the filter determines how to handle it and what response to send.

For example, you can have like a global exception filter that can catch all exceptions, log the error details and return a standard error response to the client.

So this ensures that the client receives consistent error messages and that sensitive information is not exposed.

And that will make front-end developers very happy as well.

So exception filters provide a centralized way of handling errors and maintain the stability and security of your application.

Everything that I've just shown you needs to be applied if you want these concepts to stick.

You can watch this next video and apply those concepts, and you can follow along as I build a podcast API from scratch.

And in that video, I'll also show you how to test your app.

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為什麼通過這個影片練習口語？

觀看這段影片可以幫助您更好地理解 NestJS 框架的核心概念，同時也是提升英語口語能力的絕佳機會。通過模仿影片中的講話者，您可以在實踐中運用新的詞彙和句子結構，進而增強您的自信心。利用 英語口語練習 的材料，您能逐漸提高語音語調，掌握技術相關的討論，尤其是在程式設計和開發的語境中，從而與其他英語使用者更有效地溝通。通過 shadow speak 技術，您可以一邊聽一邊說，幫助您的大腦更好地消化資訊，快速抻出反應。

語法和表達的語境

在這段影片中，演講者運用了多種有效的語法結構，以下是三個關鍵的例子：

條款和條件句：例如“if it breaks, I wouldn’t be able to fix it”，這種結構常用於描述假設和條件，幫助聽者理解潛在情況。
被動語態：使用“be used by”來強調主語接收動作的狀態，對於學習技術性表達非常重要。
動詞不定式：如“to create scheduled tasks”，助於學生理解目的或意圖，方便在日常對話中應用。

同樣，運用 shadowspeak 方法，您可以在語境中重複這些句型，增強記憶和流利度。

常見的發音陷阱

在影片中，有一些詞彙和發音可能會對學習者造成挑戰。例如，“decorators”和“applications”這兩個詞可能在快速的語速中容易被髮音錯誤。另一個注意的點是“microservices”，如果不熟悉這一術語，可能會出現重音的不當使用。建議您在觀看時重複這些單詞，利用 shadow speech 的技巧，幫助克服發音困難。

通過專注於這些具體的語言點，您不僅能夠提高對 NestJS 的理解，還能在實際交流中更自如地使用英語，提升您的 英語口語練習 能力。

影片中的語法

說話人最常用的結構，並附上影片中的原話：

結構	影片中的用法
被動語態 be + 過去分詞 — 強調發生了什麼，而不是誰做的	is not often talked · is annotated · can be attached
現在完成時 have/has + 過去分詞 — 過去發生但與現在仍有關聯的事	have you ever wondered · I've condensed · I've just shown

什麼是跟讀法？

跟讀法 (Shadowing) 是一種有科學依據的語言學習技巧，最初開發用於專業口譯員的培訓，並由多語言者Alexander Arguelles博士普及。這個方法簡單而強大：您在聽英語母語原聲的同時立即大聲重複——就像是一個延遲1-2秒緊跟說話者的影子。與被動聽力或語法練習不同，跟讀法強迫您的大腦和口腔肌肉同時處理並模模擬實的講話模式。研究表明它能顯著提高發音準確性，語調，節奏，連讀，聽力理解和口語流利度——使其成為雅思口語備考和真實英語交流最有效的方法之一。

影子跟讀法: 閱讀完整分步指南 →

跟讀練習: Every NestJS Concept Explained in 9 Minutes - 通過影片學習英語口語

選擇練習模式

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為什麼通過這個影片練習口語？

語法和表達的語境

常見的發音陷阱

影片中的語法

什麼是跟讀法？