Class: Query

Inherits:
Object
  • Object
show all
Defined in:
lib/query.rb

Constant Summary collapse

TERMINATING_FUNCTIONS = 
[:pluck]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attribute, condition, argument) ⇒ Query

Returns a new instance of Query.



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# File 'lib/query.rb', line 5

def initialize(attribute, condition, argument)
  @attribute = attribute
  @condition = condition
  @argument = argument
end

Instance Attribute Details

#argument ⇒ Object (readonly)

Returns the value of attribute argument.



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# File 'lib/query.rb', line 2

def argument
  @argument
end

#attribute ⇒ Object (readonly)

Returns the value of attribute attribute.



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# File 'lib/query.rb', line 2

def attribute
  @attribute
end

#condition ⇒ Object (readonly)

Returns the value of attribute condition.



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# File 'lib/query.rb', line 2

def condition
  @condition
end

Instance Method Details

#argument_is_block? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/query.rb', line 21

def argument_is_block?
  @argument.respond_to?(:call)
end

#attribute_present?(records) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/query.rb', line 17

def attribute_present?(records)
  records.any? { |record| record.keys.include? @attribute }
end

#conditional(row, condition, argument) ⇒ Object 



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# File 'lib/query.rb', line 48

def conditional(row, condition, argument)
  thing_to_check = row[@attribute] # for direct comparison methods

  case condition
  when :gt
    thing_to_check > argument
  when :lt
    thing_to_check < argument
  when :eq
    thing_to_check == argument
  when :between
    argument.include?(thing_to_check) 
  when :ilike
    thing_to_check.downcase.include? argument.downcase
  when :lambda
    argument.call(OpenStruct.new(row)) # lambda takes the whole row
  else
    raise "Unknown Conditional: #{condition}"
  end
end

#filter(results) ⇒ Object 



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# File 'lib/query.rb', line 29

def filter(results)
  if @attribute.empty?
    handle_terminating_function(results)
  else
    results.select do |result|
      conditional(result, @condition, @argument)
    end
  end
end

#handle_terminating_function(results) ⇒ Object 



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# File 'lib/query.rb', line 39

def handle_terminating_function(results)
  case @condition
  when :pluck
    results.map { |r| r[@argument] }
  else
    raise "Unknown Terminating Function: #{@condition}"
  end
end

#terminating_function? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/query.rb', line 25

def terminating_function?
  TERMINATING_FUNCTIONS.include?(@condition)
end

#valid?(records) ⇒ Boolean

Returns:

  • (Boolean)

Raises:

  • (ArgumentError) 


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# File 'lib/query.rb', line 11

def valid?(records)
  valid = attribute_present?(records) || argument_is_block? || terminating_function?
  raise ArgumentError.new("The attribute `#{@attribute}` is not present in the PStore.") unless valid
  valid
end