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dreamable/RailsNotes
ID 标题 笔记 Tag
5
Array & Hash
  • Hash with specified keys
    h.slice(:key1,:key2)
    h.slice(*[:key1,:key2])
  • Hash: convert key to symbols
    h.symbolize_keys
4
insert_all

note
Rails 6 adds insert_all, insert_all!, upsert_all for bulk insertion

  • insert_all(attributes, returning: nil, unique_by: nil)
    This method can be used to insert multiple records with a single SQL INSERT statement. The method simply skips ActiveRecord callbacks or validations. It accepts array of hashes, where every hash determines the attributes for a single record or row.

  • insert_all!(attributes, returning: nil)
    This method works same as that of insert_all but in addition to that it raises ActiveRecord::RecordNotUnique if any record violates a unique index on the table.

  • upsert_all(attributes, returning: nil, unique_by: nil)
    It updates the records if they exist or simply inserts them into database with a single SQL INSERT statement.

NOTE:

  • Can't use reference: i.e. use user_id instead of user
  • Must provide value for all fields, e.g. created_at, updated_at
3
destroy_all vs delete_all

  • https://stackoverflow.com/questions/6698207/delete-all-vs-destroy-all

    • destroy_all: call destroy method of all matched objects. i.e. one SQL for one object

    • delete_all: one SQL delete for all matched results.

      • NOTE：It seems to be update if use reference e.g. 

           table.datetime_cells.delete_all 
    DatetimeCell Update All (0.3ms)  UPDATE "datetime_cells" SET "table_id" = $1 WHERE "datetime_cells"."table_id" = $2  [["table_id", nil], ["table_id", 7]]
   datetime_cells.where(table:talbe).delete_all # OK
2
Calendar

simple_calendar or DIY

  1. gem
    gem simple_calendar

  2. scss
    include the default stylesheet for the calendar in your app/assets/stylesheets/application.css file

    *= require simple_calendar

    highlight start-date in app/assets/stylesheets/simple-calender.scss

    .simple-calendar {
  .start-date {
      background-color: coral
  }
}

  3. views

    <%= month_calendar start_date_param: :date  do |date| %>
  <%= date.day %>
<% end %>
1
wicked_pdf

采用wicked_pdf产生PDF文档

  1. Gemfile

    gem 'wicked_pdf'
gem 'wkhtmltopdf-binary'
#gem 'wkhtmltopdf-binary-edge' # fork of wkhtmltopdf-binary，不需要

  2. install libxrender1

    • Error, error while loading shared libraries: libXrender.so.1
    • Solution: Need to install sudo apt-get install libxrender1

  3. in config/initializers/mime_types.rb

    Mime::Type.register "application/pdf", :pdf
    • Optional? PDF may be builtin for new version.

  4. define template in app/views/layouts/pdf.html.erb

        <!doctype html>
    <html>
    <head>
        <meta charset='utf-8' />
        <%= javascript_include_tag "https://code.jquery.com/jquery-3.3.1.slim.min.js" %>
        <%= javascript_include_tag "http://code.jquery.com/ui/1.10.3/jquery-ui.min.js" %>
        <%= javascript_include_tag "https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" %>
        <%= javascript_include_tag "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" %>
    </head>
    <body onload='number_pages'>
        <div id="header">
        </div>
        <div id="content">
        <%= yield %>
        </div>
    </body>
    </html>
    • NOTE: In the official guide, you can include local css/js, but you need to define it and pre-compile it for production. Otherwise, the missing assets could be OK in development but failed in production 
        <%= wicked_pdf_stylesheet_link_tag "pdf" -%>
    <%= wicked_pdf_javascript_include_tag "number_pages" %>
    • although include jquery & bootstrap cdn in pdf.html.erb, but seems not work.

  5. specify template

    • define default template in config/initlializers/wicked_pdf.rb
       layout: 'pdf.html'
    • specify in page view when using it.

  6. Use it in controllers 

    in  app/controller/records_controller.rb
  format.pdf do
    render pdf: "records",
    template: "records/index.html.erb"
#        layout: "pdf.html"
  end
    • You could customized layout template here.

  7. If you use assets, pre-compile it for production. in config/initializers/assets.rb. e.g. 

    Rails.application.config.assets.precompile += ['blueprint/screen.css', 'pdf.css', 'jquery.ui.datepicker.js', 'pdf.js']
    • Not used and tested yet.

  8. Chinese character problem.

    • set UTF8 in layout <meta charset='utf-8' />
    • install font: sudo apt-get install fonts-wqy-zenhei

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