This article will discuss how to export data as a CSV from the Rails controller by using formats. First, set up the application and seed in some data.
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rails new csv-export
bundle
rails db:create db:migrate
rails g scaffold Post title body:text author:string likes:integer comments:integer
rails db:migrate
Let’s put some data in:
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# db/seeds.rb
Post.create(title: "Post 1", body: "This is the content of Post 1", author: "The first Author", likes: 1000, comments: 550)
Post.create(title: "Post 2", body: "This is the content of Post 2", author: "The second Author", likes: 2000, comments: 650)
Post.create(title: "Post 3", body: "This is the content of Post 3", author: "The third Author", likes: 3000, comments: 750)
Post.create(title: "Post 4", body: "This is the content of Post 4", author: "The forth Author", likes: 4000, comments: 850)
Post.create(title: "Post 5", body: "This is the content of Post 5", author: "The fifth Author", likes: 5000, comments: 950)
Post.create(title: "Post 6", body: "This is the content of Post 6", author: "The sixth Author", likes: 6000, comments: 1050)
Now, in post.rb, declare a method which will be responsible for generating data in CSV format. Depending upon your Rails version and the dependencies added, it’s possible you’ll need to add a require statement.
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# app/models/post.rb
require 'csv'
def self.to_csv
posts = all
CSV.generate do |csv|
csv << column_names
posts.each do |post|
csv << post.attributes.values_at(*column_names)
end
end
end
Next, update the index action in posts_controller.rb like below:
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# app/controllers/posts_controller.rb
def index
@posts = Post.all
respond_to do |format|
format.html
format.csv { send_data Post.to_csv, filename: "posts-#{DateTime.now.strftime("%d%m%Y%H%M")}.csv"}
end
end
Lastly, in posts/index.html.erb, add a button like this:
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# app/views/posts/index.html.erb
<%= link_to "Export", posts_path(format: 'csv') %>
Now a CSV file will be generated and downloaded on the system. Happy exporting!