How to give a date a background color with axlsx?

Question

I create an excel with axslx. One row should be colored. But if I do so, I loose the date format for my dates.

Minimal example with some attempts I did:

Answer 1

You will need to specify the number format as well so your style would look like

style1 = ws.styles.add_style(:bg_color => "EF0920", :fg_color => "FFFFFF", :format_code => "dd.mm.yyyy")

When adding a style it will overwrite the default style and all formatting. e.g.

ws.add_row [ Date.today, "Style with colors --The date is no date any longer"], :style => [style1,nil]

This will produce a red date formatted like the other rows and a no fill column B.

This style will be for the date only so if you want the whole column I would recommend something like

red_style_h  = {:bg_color => "EF0920", :fg_color => "FFFFFF"} 
red_date_h = red_style_h.merge(:format_code => "dd.mm.yyyy")

red_style = ws.styles.add_style(red_style_h)
red_date_style = ws.styles.add_style(red_date_h)

Then style your rows as

ws.add_row [ Date.today, "Style with colors --The date is no date any longer"], :style => [red_date_style,red_style]

This will produce a red row (columns A and B) with the date formatted the same as the other rows.

Git Hub Source

There are also predefined styles available through numFmts and the global named constants NUM_FMT_PERCENTAGE,NUM_FMT_YYYYMMDD,NUM_FMT_YYYYMMDDHHMMSS, etc.

When defining many different formats I find it easiest to use a YML file and then parse that to define styles e.g.

red_style:&red
  bg_color: "EF0920"
  fg_color: "FFFFFF"
red_date: 
  <<: *red
  format_code: dd.mm.yyyy

Then something like

class MyStylizedSheet < ::Axlsx::Workbook
  STYLES_FILE = YAML.load(File.read(YOUR_YML_FILE)).deep_symbolize_keys
  PREDEFINED_STYLES = {}
  def initialize(options={})
    super
    initialize_with_styles
  end
  private
  def initialize_with_styles
    STYLES_FILE.each do |k,v|
      PREDEFINED_STYLES[k] = @styles.add_style(v)
    end
  end
end

Then you can initiate your Workbook from your custom class and reference styles through the PREDEFINED_STYLES constant.