Module: Pandas::IO::Helpers

Defined in:
lib/pandas/io/active_record.rb

Class Method Summary collapse

Class Method Details

.data_frame_from_query_result(result, index_col, coerce_float, parse_dates) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 54

def data_frame_from_query_result(result, index_col, coerce_float, parse_dates)
  records = result.map {|row| row.values }
  df = Pandas::DataFrame.from_records(
    records,
    columns: result.columns,
    coerce_float: coerce_float
  )
  # TODO: self.sql._harmonize_columns(parse_dates: parse_dates)
  df.set_index(index_col, inplace: true) if index_col
  df
end

.parse_read_sql_query_args(*args) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 83

def parse_read_sql_query_args(*args)
  kwargs = args.pop if args.last.is_a? Hash
  if kwargs
    names = [:index_col, :coerce_float, :parse_dates, :chunksize]
    names.each_with_index do |name, index|
      if kwargs.has_key? name
        if args[index]
          warn "#{name} is given as both positional and keyword arguments"
        else
          args[index] = kwargs[name]
        end
      end
    end
  end
  args
end

.parse_read_sql_table_args(*args) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 66

def parse_read_sql_table_args(*args)
  kwargs = args.pop if args.last.is_a? Hash
  if kwargs
    names = [:index_col, :coerce_float, :parse_dates, :columns, :schema, :chunksize]
    names.each_with_index do |name, index|
      if kwargs.has_key? name
        if args[index]
          warn "#{name} is given as both positional and keyword arguments"
        else
          args[index] = kwargs[name]
        end
      end
    end
  end
  args
end

.read_sql_query_from_active_record(query, conn, *args) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 18

def read_sql_query_from_active_record(query, conn, *args)
  case conn
  when ActiveRecord::ConnectionAdapters::AbstractAdapter
    read_sql_query_from_active_record_connection(query, conn, *args)
  else
    raise TypeError, "unexpected type of argument #{conn.class}"
  end
end

.read_sql_query_from_active_record_connection(query, conn, *args) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 46

def read_sql_query_from_active_record_connection(query, conn, *args)
  args = parse_read_sql_query_args(*args)
  index_col, coerce_float, parse_dates, chunksize = *args
  # TODO: chunksize
  result = conn.exec_query(query, 'pandas_sql')
  data_frame_from_query_result(result, index_col, coerce_float, parse_dates)
end

.read_sql_table_from_active_record(table_name, conn, *args) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 9

def read_sql_table_from_active_record(table_name, conn, *args)
  case conn
  when ActiveRecord::ConnectionAdapters::AbstractAdapter
    read_sql_table_from_active_record_connection(table_name, conn, *args)
  else
    raise TypeError, "unexpected type of argument #{conn.class}"
  end
end

.read_sql_table_from_active_record_connection(table_name, conn, *args) ⇒ Object 



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# File 'lib/pandas/io/active_record.rb', line 27

def read_sql_table_from_active_record_connection(table_name, conn, *args)
  args = parse_read_sql_table_args(*args)
  index_col, coerce_float, parse_dates, columns, schema, chunksize = *args
  if columns
    table_columns = conn.columns(table_name)
    column_names = columns.select {|c| table_columns.include?(c) }.map do |c|
      conn.quote_column_name(c.to_s)
    end
  else
    column_names = '*'
  end
  query = <<-SQL
  select #{column_names} from #{conn.quote_table_name(table_name)};
  SQL
  # TODO: chunksize
  result = conn.exec_query(query, 'pandas_sql')
  data_frame_from_query_result(result, index_col, coerce_float, parse_dates)
end