Storing file in PostgreSQL database using NestJS

Question

I have one form in React. It has many fields. once user click on the submit button all the field should be saved in database. It also contains one file attachment(pdf).

I dont know what the datatype of variable which will store file, I should take in entity class. Also what should be the database column type. I am using TypeORM for the same.

   @IsNotEmpty()
    @IsDate()
    endDate: Date;
    @Column()
    @IsNotEmpty()
    @IsString()
    personIncharge: string;

    @Column()
    @IsNotEmpty()
    @IsString()
    country: string;

    @Column()
    @IsNotEmpty()
    @IsString()
    comments: string;

    attachFile: string;  // Should I take file or string?

Argann B. · Accepted Answer · 2021-11-05 17:16:34Z

4

+25

You will probably find your solution in this StackOverflow comment

Basically, you turn your column type in a blob or longblob in your TypeORM annotation, and then use the type Buffer in your Entity's field

@Column({type: 'longblob'})
attachFile: Buffer;

Then you will be able to serve the file as showed in the post example:

app.get("/file/:id", async (req, res)=>{
    try {
        const repo = getConnection().getRepository(MYFile)
        const result_find = await repo.findOne(req.params.id)
        console.log(result_find);
        var fileData = result_find.data;
        res.writeHead(200, {
        'Content-Type': result_find.mimeType,
        'Content-Disposition': 'attachment; filename=' + result_find.name,
        'Content-Length': fileData.length
        });
        res.write(fileData);
        res.end();
    } catch (error) {
        console.log(error)
        res.send("ERROR")
    }
})

answered Nov 5, 2021 at 17:16

Argann B.

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1 Comment

Shruti sharma Over a year ago

longblob does not exist in postgres. instead it will be bytea. could you please guide me using nestjs typeorm instead of express. can you guide me to create above form and upload the file in postgres using nestjs/typeorm

Ibrahim Tarigan · Accepted Answer · 2021-11-12 15:15:41Z

if you want using string, client must send base64 file to backend.
format: data:(mimetype);(charset),(encoded) -> data:image/png;base64,\ee\9f920d....

here solution, using base64 string
DTO (data transfer object)

import { IsDefined, IsNotEmpty } from 'class-validator';

export class UpdateUserAvatarDto {
  @IsDefined()
  @IsNotEmpty()
  file: string;
}

controller

@UseGuards(JwtAuthGuard)
@Patch('account/avatar')
async updateAvatar(
    @User() user: Payload,
    @Body() updateUserAvatarDto: UpdateUserAvatarDto,
    @Res() res: Response,
  ) {
    try {
      const { file } = updateUserAvatarDto;

      createFile(file, { prefix: ['user', 'avatar'], name: user.id }); // file is string base64 you can store it to database.

      return response(res, HttpStatus.OK, {
        message: 'Successfully update avatar',
      });
    } catch (e) {
      console.error(e);
      return response(res, HttpStatus.INTERNAL_SERVER_ERROR, {
        message: e,
        data: null,
      });
    }
}

if you want to create a file from base64

export const createFile = async (base64, { prefix, name }) => {
  const cleanBase64 = base64.split(',')[1];
  const buffer = Buffer.from(cleanBase64, 'base64');
  const file = await fileType.fromBuffer(buffer);
  return fs.writeFileSync(
    path.join(
      path.resolve('./'),
      ...['public', ...prefix, `${name}.${file.ext}`],
    ),
    buffer,
  );
};

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