NestLogged

This package provides some decorations to make NestJS logging simpler.
It only uses Logger provided by @nestjs/common package and some dependencies required for nestjs.

How to use

Route Logging

import {Controller, Get} from "@nestjs/common";
import {LoggedRoute} from "nlogdec";

@Controller('whatever')
export class WhateverController {
    constructor() {}

    @Get('/you/like')
    @LoggedRoute('/you/like')  // Add this!
    public async whateverYouLikeImpl() {
        return 'Whatever You Like';
    }
}

[Nest] 000000  - 00/00/0000, 00:00:00 AM     LOG [WhateverController] HIT HTTP WhateverController//you/like (whateverYouLikeImpl)
[Nest] 000000  - 00/00/0000, 00:00:00 AM     LOG [WhateverController] RETURNED RESPONSE WhateverController//you/like (whateverYouLikeImpl)

It will automatically log the call and response.

If function throws any exception, it will also catch exception, log that, and throw it again.

import {BadRequestException, Controller, Get} from "@nestjs/common";
import {LoggedRoute} from "nlogdec";

@Controller('whatever')
export class WhateverController {
    constructor() {}

    @Get('/you/like')
    @LoggedRoute('/you/like')
    public async whateverYouLikeImpl() {
        throw new BadRequestException("I don't like this") // Throwing HTTP exception here
    }
}

[Nest] 000000  - 00/00/0000, 00:00:00 AM     LOG [WhateverController] HIT HTTP WhateverController//you/like (whateverYouLikeImpl)
[Nest] 000000  - 00/00/0000, 00:00:00 AM     LOG [WhateverController] WHILE HTTP WhateverController//you/like (whateverYouLikeImpl) ERROR BadRequestException: I don't like this

Not only HTTP exception, it will also catch all exceptions and log it.

Function Logging

import {LoggedFunction} from "nlogdec";

@LoggedFunction // This decorator will do the magic for you
export async function doILikeThis(stuff: "apple" | "banana"): "yes" | "no" {
    return stuff === "apple" ? "yes" : "no"
}

LoggedFunction decorator will log function calls and returns for you.

Note: This decorator is expected to be used with a class method like Service. (we will upgrade that later, so you can use it without class)

Like LoggedRoute decorator, it will automatically catch all exceptions, log it, and throw it again.

Parameter Logging

import {LoggedParam, LoggedFunction} from "nlogdec";

@LoggedFunction
export async function doILikeThis(
    @LoggedParam("stuff") // It will add logs for parameter
    stuff: "apple" | "banana"
): "yes" | "no" {
    return stuff === "apple" ? "yes" : "no"
}

doILikeThis("apple")

HIT HTTP WhateverController//you/like (whateverYouLikeImpl) WITH stuff="apple"

It will add WITH {param}={value}, {param2}={value2} in log.
The name of parameter is decided by the first parameter of LoggedParam decorator.

This decorator also can be used with LoggedRoute.

Scoped Logging

You can do scoped logging with InjectLogger decorator.

Like tracebacks, it will add a scope and call stacks in log, so you can easily follow logs.

import {
    LoggedFunction, 
    LoggedParam, 
    InjectLogger, 
    ScopedLogger
} from "nlogdec";

@LoggedFunction
export async function doILikeThis(
    @LoggedParam("stuff") stuff: string,
    @InjectLogger logger: ScopedLogger // First of all, add this.
    // Note: If this is planned to be called outside of controller route function, 
    // this can be optional. like: (@InjectLogger logger?: ScopedLogger)
): "yes" | "no" {
    logger.log(`YAY we got ${stuff}`)
    return stuff === "apple" ? "yes" : "no"
}

Then, in controller:

import {BadRequestException, Controller, Get, Param} from "@nestjs/common";
import {
    LoggedRoute,
    InjectLogger, 
    LoggedParam, 
    ScopedLogger
} from "./logged";

@Controller('you')
export class WhateverController {
    constructor() {
    }

    @Get('/like/:thing')
    @LoggedRoute('/like/{thing}')
    public async like(
        @LoggedParam('thing') @Param('thing') thing: string,
        @InjectLogger logger: ScopedLogger,
        // When NestJS calls this function, decorator will automatically fills this logger parameter.
    ) {
        const likeThing = doILikeThis(thing, logger) === "yes"
        if (!likeThing) throw BadRequestException("I don't like this")
    }
}

The @LoggedFunction decorator that applied to doILikeThis function will intercept given logger, and make it scoped.

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