How to create validator for file uploads

[amber surge]

Currently when validating file uploads in any endpoint I'm using the following snippet:

async addPDF(
    @UploadedFile(
        new ParseFilePipeBuilder()
            .addMaxSizeValidator({
                maxSize: CONSTANTS.FILE.MAX_SIZE,
                message: CONSTANTS.FILE.MAX_SIZE_ERROR_MESSAGE,
            })
            .addFileTypeValidator({
                fileType: Commons.generateRegexFromArrayForOr(CONSTANTS.FILE.ALLOWED_FILE_TYPES),
            })
            .build()
    ) file): Promise<any> {
    
    return this.pdfService.createPDF({
        request: {
            fileContent: file,
        },
    });
}

Using this approach, I'm facing two problems:

1. There is code duplicacy when adding same logic to other endpoints.
2. The file type validator is validating based on extension.

My aim is to create a custom validator which performs type validation based on magic number and can be reused in other endpoints. It should take the size and allowed types as inputs.

Can anyone please help me how I can create one custom validator for this purpose and use it in the endpoints? Any documentation or sample code will be helpful.

Thanks

[manic island]

instead of adding a pipe you can apply a default to the multer module it self, pointed out by the docs
options can be found in the multer docs

alternatively, you can use the multer storage option and change the storage handler, like a third party one
allowing you for more option controlls

[amber surge]

I want to have the flexibility to pass the size limit and allowed types, for different endpoints, but the rest of the logic will be same. So I don't think setting default will be a good idea.

[manic island]

i dont think you got the point i was trying to make, pipes overwrite the default settings
write once, and only make changes to a route when you need to

[amber surge]

Ok understood