Tips for resolving uncaught promise rejection alerts on NestJS

Question

Tips for resolving uncaught promise rejection alerts on NestJS

I'm currently utilizing NestJS for the backend of my Angular project, and I encountered an issue after installing Swagger. Prior to the installation, everything was running smoothly. However, post-installation, a warning about an unhandled promise rejection surfaced, preventing the application from running.

If I comment out the code in the controllers, the application works fine leading me to suspect there may be an issue with async/await. Unfortunately, I am unsure about how to address this problem. Therefore, any assistance or suggestions on resolving this would be greatly appreciated.

Controller

    @Put(':id')
    async updateHelpSubsection(@Body() newHelp: HelpSubsectionModule, @Param() params): Promise<HelpSubsectionModule> {
        try{
            let oldHelpData = await this.helpSubsectionService.getHelpSubsectionbyId(params.id)
            return this.helpSubsectionService.updateHelpSubsection(oldHelpData, newHelp);
        }catch(e) {
            console.log(e)
        }
    }

Services

    async updateHelpSection(updateHelp: HelpSectionEntity, newHelpData): Promise<HelpSectionEntity> {

        Object.keys(newHelpData).forEach((key) => {
            updateHelp[key] = newHelpData[key];
        });

        try {
            return await this.helpSectionRepo.save(updateHelp);
        } catch (err) {
            throw new HttpException({
                error: err
            }, HttpStatus.FORBIDDEN)
        }
    }

This is the warning message I'm encountering: https://i.sstatic.net/wDECV.png

angular typescript warnings backend nestjs

Answer 1

Answer №1

In the quest for a solution to manage errors that haven't been handled, try out this method:

process.on('unhandledRejection', (error) => {
    console.log('handle the error...');
});

Answer 2

In the quest for a solution to manage errors that haven't been handled, try out this method:

process.on('unhandledRejection', (error) => {
    console.log('handle the error...');
});

Answer 3

Answer №2

Kindly make the necessary adjustments in the controller:

       @Put(':id')
       async updateHelpSubsection(@Body() newHelp: HelpSectionEntity, @Param() params): Promise< HelpSectionEntity> {
           try{
               let oldHelpData = await this.helpSubsectionService.getHelpSubsectionbyId(params.id)
               return this.helpSubsectionService.updateHelpSubsection(oldHelpData, newHelp);
           }catch(e) {
               console.log(e)
           }
       }

It is important to note that modules are not permitted in TypeScript types.

Kindly substitute HelpSubsectionModule with HelpSectionEntity.

Answer 4

Kindly make the necessary adjustments in the controller:

       @Put(':id')
       async updateHelpSubsection(@Body() newHelp: HelpSectionEntity, @Param() params): Promise< HelpSectionEntity> {
           try{
               let oldHelpData = await this.helpSubsectionService.getHelpSubsectionbyId(params.id)
               return this.helpSubsectionService.updateHelpSubsection(oldHelpData, newHelp);
           }catch(e) {
               console.log(e)
           }
       }

It is important to note that modules are not permitted in TypeScript types.

Kindly substitute HelpSubsectionModule with HelpSectionEntity.

Answer 5

Answer №3

Unsure about the functioning of @Put(:id), however, updateHelpSection does provide a promise that needs to be managed using .then() to retrieve data upon successful resolution and catch() to handle errors in case of rejection. For further information, refer to this insightful article

Answer 6

Unsure about the functioning of @Put(:id), however, updateHelpSection does provide a promise that needs to be managed using .then() to retrieve data upon successful resolution and catch() to handle errors in case of rejection. For further information, refer to this insightful article

Answer 7

Answer №4

Remember, what you are seeing here is simply a reminder of best practices.

It's important for every Promise to have error handling in place when making requests.

For instance:

Take this Promise as an example.

const slowAndSteady = new Promise(function(resolve, reject) {
    reject();
});

If you utilize async/await in the following manner.

(async function() {
    await slowAndSteady();
})();

You may encounter an UnhandledPromiseRejectionWarning, but by employing it like this.

slowAndSteady
    .then(function(result) {
        console.log('result', result);
    })
    .catch(function(err) {
        console.log('error: ', err);
    });

The warning will disappear.

In case you still wish to use async/await, you have two options.

(async () => {
  try {
    const result = await slowAndSteady();
    console.log('result', result);
  } catch(e) {
    console.log('Error caught',e);
  }
})();

Alternatively,

(async () => {
  const result = await slowAndSteady().catch((e) => console.log('Error caught',e));
  console.log('result', result);
})();

Answer 8

Remember, what you are seeing here is simply a reminder of best practices.

It's important for every Promise to have error handling in place when making requests.

For instance:

Take this Promise as an example.

const slowAndSteady = new Promise(function(resolve, reject) {
    reject();
});

If you utilize async/await in the following manner.

(async function() {
    await slowAndSteady();
})();

You may encounter an UnhandledPromiseRejectionWarning, but by employing it like this.

slowAndSteady
    .then(function(result) {
        console.log('result', result);
    })
    .catch(function(err) {
        console.log('error: ', err);
    });

The warning will disappear.

In case you still wish to use async/await, you have two options.

(async () => {
  try {
    const result = await slowAndSteady();
    console.log('result', result);
  } catch(e) {
    console.log('Error caught',e);
  }
})();

Alternatively,

(async () => {
  const result = await slowAndSteady().catch((e) => console.log('Error caught',e));
  console.log('result', result);
})();

Tips for resolving uncaught promise rejection alerts on NestJS

Answer №1

Answer №2

Answer №3

Answer №4

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