Controller, @Get(), @Post()

2022-09-13

2022-11-09

Nest.js

Generate a controller by running the Nest CLI

Command: nest generate controller, which can be abbreviated as nest g co. Then enter the name of the controller. (If you don’t want to generate test files, you should type nest g co --no-spec )

After running, nest will help us create a folder containing controller and spec files. At this time, the app.module.ts file will automatically introduce this controller to the controllers array.

If you want to create a controller in a subfolder of src, the command can be rewritten as nest generate controller modules/abc. If you want to see the simulated output, you can use nest generate controller modules/abc --dry-run. He doesn’t actually create the file.
URL access and controller matching mechanism

Nest uses @Controller('route') to match controller and url.
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@Controller('coffees') //It can be accessed when accessing http://localhost:3000/coffees with GET.
export class CoffeesController {}
When controller is empty, it will return 404 and error message. Also note that methods like Controller and Get/Post are imported from @nestjs/common.

Build http handler, Get

First introduce Methods such as Get from @nestjs/common. The corresponding methods for Get are findAll() and findOne.

import { Controller, Get } from '@nestjs/common';

@Controller('coffees')
export class CoffeesController {
     @Get()
     findAll(){
         return 'This action returns all coffees';
     }
}

Nested Paths

In a class decorated with @Controller('primary path'), secondary paths can be nested.

@Controller('coffees')
export class CoffeesController {
     @Get('flavors') //Put the secondary route here.
     findAll(){
         return 'This action returns all coffees';
     }
}

At this time, visit localhost:3000/coffees/flavors to access the content.

Use routing parameters (dynamic path)

You can use route parameters by writing (':id') in the decorator, and import Param from @nestjs/common. The @Param() decorator allows us to take all incoming request parameters and use them in the body of the method.

When nothing is passed inside the @Param() decorator, it receives all request parameters, let’s access params.id from the object.

import { Controller, Get, Param } from '@nestjs/common';

@Controller('coffees')
export class CoffeesController {
    @Get(':id') //Put the secondary route here.
    findOne(@Param() params){
        return `This action returns #${params.id} coffees`;
    }
}

When the @Param() decorator passes in a parameter, first declare the parameter type, and then use the parameter directly.

import { Controller, Get, Param } from '@nestjs/common';

@Controller('coffees')
export class CoffeesController {
    @Get(':id')
    findOne(@Param('id') id: string){ //The parameter type is declared here.
        return `This action returns #${id} coffees`;
    }
}

Post and @Body decorators

The @Body decorator is used to get all or specific parts of request.body. Note that both Post and Body are imported from @nestjs/common. The corresponding method of Post is create .

import { Controller, Get, Param, Post, Body } from '@nestjs/common';

@Controller('coffees')
export class CoffeesController {
     @Post()
     create(@Body() body){
         return body;
     }
}

As with the @Param decorator, it is possible not to access the body as a whole, but a specific part.

import { Controller, Get, Param, Post, Body } from '@nestjs/common';

@Controller('coffees')
export class CoffeesController {
     @Post()
     create(@Body('name') body){ //Incoming parameters
         return body;
     }
}

The problem with this way is that if only certain properties are accessed, other properties will not be validated.

Derek Zhu

Back-endNest.js

Controller, @Get(), @Post()