In a Ruby on Rails app I was working on, I wanted to include a link that would download a user’s data (bank statements in this case) as JSON.

Originally I had the following ERB:

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<%= link_to 'Download All Statements as JSON', statements_download_path %>

Clicking this link would show JSON in the browser, but it wouldn’t download a JSON file, which is what I wanted.

The solution was to add a download attribute to the ERB snippet:

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<%= link_to 'Download All Statements as JSON', statements_download_path, download: 'statements.json' %>

Full Setup

For additional context, here is all the code required to get this to work.

First I created this method in statements_controller.rb:

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def download
  render json: @user.statements
end

Then I added a new route to routes.rb:

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get 'statements/download', to: 'statements#download'

And then I added the link_to helper in the view:

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<%= link_to 'Download All Statements as JSON', statements_download_path, download: 'statements.json' %>

The link_to ERB helper is creating this HTML:

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<a download="statements.json" href="/statements/download">Download All Statements as JSON</a>

The download attribute can be customized in ERB. For example, I can name the file based on the user’s name like so:

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<%= link_to 'Download All Statements as JSON', statements_download_path, download: "#{@user.name.downcase}-statements" %>

And it will generate the following HTML:

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<a download="nelson-statements" href="/statements/download">Download All Statements as JSON</a>

This link will trigger a download for nelson-statements.json in my case.

Ultimately this was a case of understanding the download HTML attribute for <a> tags and how to use it in Rails.

Further Reading and References

Note that there are other ways of handling this, like using the send_data method in a controller. But that’s beyond the scope of this post. Read more about it here: https://api.rubyonrails.org/v7.0.1/classes/ActionController/DataStreaming.html#method-i-send_data

References: