Class: CsvOrm::Query

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data) ⇒ Query

Returns a new instance of Query.



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

def initialize(data)
  @data = data
  nil # suppress output
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/csv_orm/query.rb', line 3

def data
  @data
end

Instance Method Details

#aggregate(*fields) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 18

def aggregate(*fields)
  agg = {}
  @data.each do |row|
    fields.each do |field|
      agg[field] ||= {}
      agg[field][row.send(field)] ||= 0
      agg[field][row.send(field)] += 1
    end
  end
  agg
end

#build_expression(conditional, attrs) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 83

def build_expression(conditional, attrs)
  string   = ''
  is_first = true

  attrs.each do |k, v|
    string << " #{conditional} " unless is_first
    string << build_expression_part(k, v)
    
    is_first = false
  end
  string
end

#build_expression_part(key, value) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 67

def build_expression_part(key, value)
  case
  when value.class == String
    "row.send(:#{key}) == '#{value}'"
  when value.class == Regexp
    "row.send(:#{key}).match(/#{value.source}/)"
  when value.class == Array
    "#{value}.include?(row.send(:#{key}))"
  when value.class == Range
    parsed_range_value = parse_range_values(value)
    "(#{parsed_range_value}).cover?(row.send(:#{key}))"
  when [TrueClass, FalseClass].include?(value.class)
    "row.send(:#{key}) == '#{value.to_s}'"
  end
end

#explain(method, args) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 30

def explain(method, args)
  case
  when method == :where 
    build_expression('&&', args)
  when method == :where_any
    build_expression('||', args)
  else
    'not supported at this time'
  end
end

#not(attrs) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 51

def not(attrs)
  expression = build_expression('&&', attrs)
  self.class.new(@data.reject {|row| eval(expression)});
end

#parse_range_values(range) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 56

def parse_range_values(range)
  exclude = range.exclude_end?
  first, last = DateTime.parse(range.begin), DateTime.parse(range.end) rescue nil
  
  if first && last
    Range.new(first.to_time.to_i, last.to_time.to_i, exclude)
  else
    range
  end
end

#queryable_fields ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 14

def queryable_fields
  @data&.first&.to_h&.keys
end

#size ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 10

def size
  @data.size
end

#where(attrs) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 46

def where(attrs)
  expression = build_expression('&&', attrs)
  self.class.new(@data.select {|row| eval(expression)});
end

#where_any(attrs) ⇒ Object 



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# File 'lib/csv_orm/query.rb', line 41

def where_any(attrs)
  expression = build_expression('||', attrs)
  self.class.new(@data.select {|row| eval(expression)});
end