Class: Clevic::Sampler

Inherits:
Object show all
Defined in:
lib/clevic/sampler.rb

Overview

This is used as part of the process of calculating the width of a field in the UI. Since the font is important, this computes a string value for a field that can be given to the font metrics for a framework. Uses various heuristics to compute the string values for different kinds of fields.

Defined Under Namespace

Classes: VirtualField

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(field, &format_block) ⇒ Sampler

display is only used for relational fields



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# File 'lib/clevic/sampler.rb', line 13

def initialize( field, &format_block )
  @field = field
  @format_block = format_block
end

Instance Attribute Details

#field ⇒ Object (readonly)

Returns the value of attribute field.



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# File 'lib/clevic/sampler.rb', line 17

def field
  @field
end

Instance Method Details

#compute ⇒ Object

return a string which is representative of the width of the field



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# File 'lib/clevic/sampler.rb', line 36

def compute
  if field.set
    # choose the longest value in the set
    set = field.set_for( entity_class.first )
    if set.is_a?( Hash )
      set.values
    else
      set
    end. \
    max{|a,b| a.to_s.length <=> b.to_s.length }.to_s.upcase
  else
    # choose samples based on the type of the field
    case meta.type
    when :boolean
      field.label

    when :string, :text
      string_sample

    when :date, :time, :datetime, :timestamp
      date_time_sample

    when :numeric, :decimal, :integer, :float
      numeric_sample

    # TODO return a width, or something like that
    when :boolean; 'W'

    when :many_to_one
      related_sample

    else
      unless meta.type.nil?
        raise "Sampler#compute can't figure out sample for #{entity_class.name}##{field_name} because it's a #{meta.type.inspect}"
      end
    end
  end
end

#date_time_sample ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 94

def date_time_sample
  # replace all letters with 'N'
  # and numbers with 8
  do_format( sample_date_time || Date.today ).andand.gsub( /[[:alpha:]]/, 'N' ).gsub( /\d/, '8' )
end

#display ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 27

def display
  field.display
end

#do_format(value) ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 75

def do_format( value )
  @format_block.call( value )
end

#entity_class ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 19

def entity_class
  field.entity_class
end

#field_name ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 23

def field_name
  field.attribute
end

#meta ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 31

def meta
  field.meta
end

#numeric_sample ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 100

def numeric_sample
  max = entity_class.max( field_name )
  min = entity_class.min( field_name )
  max_length = [ do_format( min ).to_s, do_format( max ).to_s ].map( &:length ).max
  '9' * ( max_length || 5 )
end

#related_sample ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 120

def related_sample
  if display.respond_to?( :to_sym )
    Sampler.new( VirtualField.new( eval( meta.class_name ), display.to_sym ), &@format_block ).compute
  end
end

#sample_date_time ⇒ Object 



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# File 'lib/clevic/sampler.rb', line 84

def sample_date_time
  ds = entity_class \
    .filter( ~{ field_name => nil } ) \
    .select( field_name ) \
    .limit(1)
  # can't use single-value here because the typecast_on_load
  # isn't called unless we access the value via the entity object
  ds.first.send( field_name )
end

#string_sample ⇒ Object

default to max length of 20



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# File 'lib/clevic/sampler.rb', line 80

def string_sample
  'N' * ( entity_class.max( :length.sql_function( field_name ) ).andand.to_i || 20 )
end