Iteration 4: Data Access and Relationships: Economic Profile

Data Access Layer

EconomicProfileRepository

The EconomicProfileRepository is responsible for holding and searching our EconomicProfile instances. It offers the following methods:

• #find_by_name - returns either nil or an instance of EconomicProfile having done a case insensitive search

The EconomicProfile instances are built using these data files:

• Median household income.csv
• School-aged children in poverty.csv
• Students qualifying for free or reduced price lunch.csv
• Title I students.csv

The repository is initialized and used like this:

epr = EconomicProfileRepository.new
epr.load_data({
  :economic_profile => {
    :median_household_income => "./data/Median household income.csv",
    :children_in_poverty => "./data/School-aged children in poverty.csv",
    :free_or_reduced_price_lunch => "./data/Students qualifying for free or reduced price lunch.csv",
    :title_i => "./data/Title I students.csv"
  }
})
ep = epr.find_by_name("ACADEMY 20")
# => <EconomicProfile>

EconomicProfile

An instance of this class contains the data from the file above for a single district. We would create one like this:

data = {:median_household_income => {[2005, 2009] => 50000, [2008, 2014] => 60000},
        :children_in_poverty => {2012 => 0.1845},
        :free_or_reduced_price_lunch => {2014 => {:percentage => 0.023, :total => 100}},
        :title_i => {2015 => 0.543},
        :name => "ACADEMY 20"
       }
economic_profile = EconomicProfile.new(data)

And it would offer the following methods:

#median_household_income_in_year(year)

This method takes one parameter:

• year as an integer

A call to this method with an unknown year should raise an UnknownDataError.

To derive this number, we will average the values for all of the year ranges in which your requested year appears.

The method returns an integer.

Example:

economic_profile.median_household_income_in_year(2005)
=> 50000
economic_profile.median_household_income_in_year(2009)
=> 55000

#median_household_income_average

This method takes no parameters. It returns an integer averaging the known median household incomes.

This should be an average of the reported income from all the available year ranges.

Example:

economic_profile.median_household_income_average
=> 55000

#children_in_poverty_in_year(year)

This method takes one parameter:

• year as an integer

A call to this method with an unknown year should raise an UnknownDataError.

The method returns a float representing a percentage.

Example:

economic_profile.children_in_poverty_in_year(2012)
=> 0.184

#free_or_reduced_price_lunch_percentage_in_year(year)

This method takes one parameter:

• year as an integer

A call to this method with an unknown year should raise an UnknownDataError.

The method returns a float representing a percentage.

Example:

economic_profile.free_or_reduced_price_lunch_percentage_in_year(2014)
=> 0.023

#free_or_reduced_price_lunch_number_in_year(year)

This method takes one parameter:

• year as an integer

A call to this method with an unknown year should raise an UnknownDataError.

The method returns an integer representing the total number of children on Free or Reduced Price Lunch in that year.

Example:

economic_profile.free_or_reduced_price_lunch_number_in_year(2014)
=> 100

#title_i_in_year(year)

This method takes one parameter:

• year as an integer

A call to this method with an unknown year should raise an UnknownDataError.

The method returns a float representing a percentage.

Example:

economic_profile.title_i_in_year(2015)
=> 0.543

Relationships

District

We’ll add another relationship:

• #economic_profile - returns an instance of EconomicProfile