alias Tablo::Cell::Text::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::Text (headings and group), the formatter Proc can take 2 different forms, as shown below by their commonly used parameter names and types:

The default formatter is defined byTablo::Config::Defaults.heading_formatter (or Tablo::Config::Defaults.group_formatter`) and the return type is String for both.

Any processing can be done on the cell value. For example, in a group, if the runtime cell value contains a Time type, we could format as :

require "tablo"
timestamp = "15/1/2024 12:00:00"
table = Tablo::Table.new([1, 2, 3]) do |t|
  t.add_column("itself", &.itself)
  t.add_group(:g1, header: "Before\n" + timestamp)
  t.add_column("itself x 2", &.*(2))
  t.add_column("itself x 3", &.*(3))
  t.add_group(:g2, header: timestamp, formatter: ->(value : Tablo::CellType) {
    parsed = Time.parse(value.as(String), "%d/%m/%Y %H:%M:%S", Time::Location.local)
    "After\nDate = " + parsed.to_s("%Y-%m-%d") + "\nTime = " + parsed.to_s("%H:%M:%S")
  }, alignment: Tablo::Justify::Left)
end
puts table
+--------------+-----------------------------+
|    Before    | After                       |
|   15/1/2024  | Date = 2024-01-15           |
|   12:00:00   | Time = 12:00:00             |
+--------------+--------------+--------------+
|       itself |   itself x 2 |   itself x 3 |
+--------------+--------------+--------------+
|            1 |            2 |            3 |
|            2 |            4 |            6 |
|            3 |            6 |            9 |
+--------------+--------------+--------------+

Another example, to stretch contents of a cell to its maximum width:

require "tablo"
table = Tablo::Table.new([1, 2, 3],
  title: Tablo::Heading.new("My Title", framed: true,
    formatter: ->(value : Tablo::CellType, column_width : Int32) {
      Tablo::Functions.stretch(value.as(String), target_width: column_width)
    })) do |t|
  t.add_column("itself", &.itself)
  t.add_column("itself x 2", &.*(2))
  t.add_column("itself x 3", &.*(3))
end
puts table
+--------------------------------------------+
|    M    y         T    i    t    l    e    |
+--------------+--------------+--------------+
|       itself |   itself x 2 |   itself x 3 |
+--------------+--------------+--------------+
|            1 |            2 |            3 |
|            2 |            4 |            6 |
|            3 |            6 |            9 |
+--------------+--------------+--------------+

Alias Definition

Tablo::CellType, Int32 -> String | Tablo::CellType -> String

Defined in:

cell.cr