Prepend UTF-8 BOM to CSV

[kzkn]

I want to be able to prepend UTF-8 BOM ("\xEF\xBB\xBF") to the downloaded CSV file.

MS Excel does not correctly recognize UTF-8 (without BOM, it's plain) files containing non-ASCII characters. If you prepend UTF-8 BOM, it will recognize correctly. I think this is a bug of MS Excel, but there is no way to fix it. We have no choice but to avoid it.

I have confirmed that it can be avoided by applying a monkey patch to Blazer::QueriesController.

load Blazer::Engine.root.join('app/controllers/blazer/queries_controller.rb')
Blazer::QueriesController.prepend(Module.new do
  def csv_data(columns, rows, data_source)
    "\xEF\xBB\xBF" + super
  end
end)

SEE: https://stackoverflow.com/questions/2881093/override-a-rails-engine-controller-action

I want to take this as a function.
In my idea, it is good that it can be contorlled with blazer.yml to keep compatibility.

[ankane]

Hey @kzkn, thanks for the suggestion. Which versions of MS Excel are affected?

[kzkn]

@ankane
As far as I know, version 2013 and earlier are affected at least.

[kzkn]

@ankane
If I send a pull request, could you merge it?

[ankane]

Hey @kzkn, this isn't something I want to include in the gem right now. Thanks for sharing your approach. Others who need this should be able to use it.

[abrambailey]

Agree this would be a nice option. We ran into the same issue with our project.