CSV File Processing with Nestjs and Papa Parse - csv

Question

I am trying to process a CSV file in NestJS using Multer and Papa Parse. I do not want to store the file locally. I just want to parse CSV files to extract some information.
However, I am unable to process it, I have tried two different ways. In the first one, I passed the file buffer to Papa.parse function. However, I get the error: ReferenceError: FileReaderSync is not defined
#Post('1')
#UseInterceptors(
FileInterceptor('file', {})
)
async uploadFile(#UploadedFile() file: Express.Multer.File ){
const csvData = papa.parse(file.buffer, {
header: false,
worker: true,
delimiter: ",",
step: function (row){
console.log("Row: ", row.data);
}
});
}
So tried calling the readFileSync() as shown below, but this time I got the error, ERROR [ExceptionsHandler] ENAMETOOLONG: name too long, open
#Post('2')
#UseInterceptors(
FileInterceptor('file', {})
)
async uploadFile(#UploadedFile() file: Express.Multer.File ){
const $file = readFileSync(file.buffer);
const csvData = papa.parse($file, {
header: false,
worker: true,
delimiter: ",",
step: function (row){
console.log("Row: ", row.data);
}
});
}
will appreciate any help to resolve this issue.

Answer 1

As pointed out by #skink, the file buffer needs to be converted to stream before it can be used by papa parse.
const { Readable } = require('stream');
And updated the function, where converting the file.buffer to stream before calling parse()
#Post('1')
#UseInterceptors(
FileInterceptor('file', {})
)
async uploadFile(#UploadedFile() file: Express.Multer.File ){
const stream = Readable.from(file.buffer);
const csvData = papa.parse(stream, {
header: false,
worker: true,
delimiter: ",",
step: function (row){
console.log("Row: ", row.data);
}
});
}