alias Tablo::Cell::Data::Formatter

Overview

The purpose of the formatter is to transform the raw value of a cell into a formatted character string

For cells of type Tablo::Cell::Data, the Formatter Proc can take 4 different forms, as shown below by their commonly used parameter names and types:

The default formatter is defined byTablo::Config::Defaults.body_formatter (or Tablo::Config::Defaults.header_formatter) and the return type is String for all of them.

These different forms can be used for conditional formatting.

For example, to alternate case after each row, the 3rd form can be used :

require "tablo"
table = Tablo::Table.new(["A", "B", "C"],
  body_formatter: ->(value : Tablo::CellType, coords : Tablo::Cell::Data::Coords) {
    if value.is_a?(String)
      coords.row_index % 2 == 0 ? value.as(String).upcase : value.as(String).downcase
    else
      value.to_s
    end
  }) do |t|
  t.add_column("itself", &.itself)
  t.add_column("itself x 2", &.*(2))
  t.add_column("itself x 3", &.*(3))
end
puts table
+--------------+--------------+--------------+
| itself       | itself x 2   | itself x 3   |
+--------------+--------------+--------------+
| A            | AA           | AAA          |
| b            | bb           | bbb          |
| C            | CC           | CCC          |
+--------------+--------------+--------------+

This has an impact on all text columns. To limit formatting to the second column, for example, you could write:

require "tablo"
table = Tablo::Table.new(["A", "B", "C"],
  body_formatter: ->(value : Tablo::CellType, coords : Tablo::Cell::Data::Coords) {
    if value.is_a?(String) && coords.column_index == 1
      coords.row_index % 2 == 0 ? value.as(String).upcase : value.as(String).downcase
    else
      value.to_s
    end
  }) do |t|
  t.add_column("itself", &.itself)
  t.add_column("itself x 2", &.*(2))
  t.add_column("itself x 3", &.*(3))
end
puts table

or, if formatting is done directly at the column level:

require "tablo"
table = Tablo::Table.new(["A", "B", "C"]) do |t|
  t.add_column("itself", &.itself)
  t.add_column("itself x 2",
    body_formatter: ->(value : Tablo::CellType, coords : Tablo::Cell::Data::Coords) {
      if value.is_a?(String)
        coords.row_index % 2 == 0 ? value.as(String).upcase : value.as(String).downcase
      else
        value.to_s
      end
    }, &.*(2)
  )
  t.add_column("itself x 3", &.*(3))
end
puts table
+--------------+--------------+--------------+
| itself       | itself x 2   | itself x 3   |
+--------------+--------------+--------------+
| A            | AA           | AAA          |
| B            | bb           | BBB          |
| C            | CC           | CCC          |
+--------------+--------------+--------------+

Alias Definition

Tablo::CellType, Int32 -> String | Tablo::CellType -> String | Tablo::CellType, Tablo::Cell::Data::Coords, Int32 -> String | Tablo::CellType, Tablo::Cell::Data::Coords -> String

Defined in:

cell.cr