Question

I’m using express-form https://github.com/dandean/express-form

Does it have the ability to validate an input of the type file? I specifically want to require that someone upload a file.

EDIT for Linus 🙂

I’ve tried:
field("pdf").required("pdf", "You must select a file to upload.")

The problem is that this is looking for req.body.pdf not req.files.pdf, so it always thinks the validation fails.

EDIT / WORKING CODE: What I did to get it to work based on Linus’ answer.

Not only did I need to configure the dataSources param, I also needed to check the field’s size property as just doing a required on the field isn’t good enough because even if a file input is empty, it still exists (meta data, etc). So instead, I do a custom validation function that makes sure pdf.size is greater than 0. In my code, I also check to see if I have a title. I left that here in case anyone was wondering how to string together multiple validations.

var form = require('express-form')
  .configure({dataSources: ['body', 'files', 'query', 'params']});

form(
  field("pdf.size").custom(function(value) {
    if (value <= "0") {
      throw new Error("You must select a file to upload.");
    }
  })
 , field("title").trim().required("title", "Please enter a title for your PDF."))

Answer 1

From the README:

Express Form has various configuration options, but aims for sensible defaults for a typical Express application.

…

dataSources (Array): An array of Express request properties to use as data sources when filtering and validating data. Default: ["body", "query", "params"].

So something along these lines should do the trick:

var form = require('express-form')
           .configure({dataSources: ['body', 'files', 'query', 'params']});