How to use Crystal enum with the options_for_select?

[zw963]

options_for_select limit the type of first permittedAttribute args must same as the second list args value.

e.g.

class University < BaseModel
  enum BatchLevel
    LevelOne_A
    LevelOne_B
    LevelTwo_A
    LevelTwo_B

    def to_s
      case self
      in LevelOne_A
        "一本A"
      in LevelOne_B
        "一本B"
      in LevelTwo_A
        "二本A"
      in LevelTwo_B
        "二本B"
      end
    end

    def self.checkbox_batch_level
      values = [] of Tuple(String, Int32)

      BatchNumber.each { |bn| values << {bn.to_s, bn.value} }

      values
    end
  end

  table do
    column batch_level : University::BatchLevel
  end
end

In the page

options_for_select(op.batch_level, University::BatchNumber.checkbox_batch_level)

This will get error like this:

Error: no overload matches 'Universities::FormFields#options_for_select' with types
Avram::PermittedAttribute(University::BatchNumber), Array(Tuple(String, Int32))

AFAIK, there is two solution:

1. change column batch_level type to Int32, but this is not good, because we want use Enum

2. Add an attribute batch_number : Int32 in the SaveUniversity to handle this.

I consider both of them not good, is there a better way to do this?

thanks

[zw963]

It seem like works change code like this:

class University < BaseModel
  enum BatchLevel
    LevelOne_A
    LevelOne_B
    LevelTwo_A
    LevelTwo_B

    def display_name
      case self
      in LevelOne_A
        "一本A"
      in LevelOne_B
        "一本B"
      in LevelTwo_A
        "二本A"
      in LevelTwo_B
        "二本B"
      end
    end

    def self.checkbox_batch_level
      values = [] of Tuple(String, University::BatchLevel)

      BatchNumber.each { |bn| values << {bn.display_name, bn} }

      values
    end
  end

  table do
    column batch_level : University::BatchLevel
  end
end

Then use in page like this:

options_for_select(op.batch_level, University::BatchNumber.checkbox_batch_level)