contacts/app/models/person.rb

class Person
    # connect to postgres
    DB = PG.connect({:host => "localhost", :port => 5432, :dbname => 'contacts'})

    def self.all
        results = DB.exec(
            <<-SQL
                SELECT
                    people.*,
                    locations.street,
                    locations.city,
                    locations.state,
                    companies.id AS company_id,
                    companies.name AS company,
                    companies.industry
                FROM people
                LEFT JOIN locations
                    ON people.home_id = locations.id
                LEFT JOIN jobs
                    ON people.id = jobs.person_id
                LEFT JOIN companies
                    ON jobs.company_id = companies.id
            SQL
        )
        people = []
        last_person_id = nil
        results.each do |result|
            if result["id"] != last_person_id
                last_person_id = result["id"]
                if result["home_id"]
                    home = {
                        "id" => result["home_id"],
                        "street" => result["street"],
                        "city" => result["city"],
                        "state" => result["state"],
                    }
                end
                new_person = {
                    "id" => result["id"],
                    "name" => result["name"],
                    "age" => result["age"],
                    "home" => home,
                    "employers" => []
                }
                people.push(new_person)
            end
            if result["company_id"]
                employer = {
                    "id" => result["company_id"].to_i,
                    "name" => result["company"],
                    "industry" => result["industry"]
                }
                people.last["employers"].push(employer)
            end
        end
        return people
    end

    def self.find(id)
        results = DB.exec(
            <<-SQL
                SELECT
                    people.*,
                    locations.street,
                    locations.city,
                    locations.state,
                    companies.id AS company_id,
                    companies.name AS company,
                    companies.industry
                FROM people
                LEFT JOIN locations
                    ON people.home_id = locations.id
                LEFT JOIN jobs
                    ON people.id = jobs.person_id
                LEFT JOIN companies
                    ON jobs.company_id = companies.id
                WHERE people.id=#{id};
            SQL
        )
        result = results.first
        if result["home_id"]
            home = {
                "id" => result["home_id"],
                "street" => result["street"],
                "city" => result["city"],
                "state" => result["state"],
            }
        end

        employers = []
        results.each do |result|
            if result["company_id"]
                employers.push( {
                    "id" => result["company_id"].to_i,
                    "name" => result["company"],
                    "industry" => result["industry"]
                })
            end
        end
        person =  {
            "id" => result["id"],
            "name" => result["name"],
            "age" => result["age"],
            "home" => home,
            "employers" => employers
        }
        return person
    end

    def self.create(opts={})
        results = DB.exec(
            <<-SQL
                INSERT INTO people (name, age, home_id)
                VALUES ( '#{opts["name"]}', #{opts["age"]},  #{opts["home_id"] ? opts["home_id"] : "NULL"})
                RETURNING id, name, age, home_id;
            SQL
        )
        return {
            "id" => results.first["id"].to_i,
            "name" => results.first["name"],
            "age" => results.first["age"].to_i,
            "home_id" => results.first["home_id"].to_i,
        }
    end

    def self.delete(id)
        results = DB.exec("DELETE FROM people WHERE id=#{id};")
        return { "deleted" => true }
    end

    def self.update(id, opts={})
        results = DB.exec(
            <<-SQL
                UPDATE people
                SET name='#{opts["name"]}', age=#{opts["age"]}, home_id=#{opts["home_id"] ? opts["home_id"] : "NULL"}
                WHERE id=#{id}
                RETURNING id, name, age, home_id;
            SQL
        )
        return {
            "id" => results.first["id"].to_i,
            "name" => results.first["name"],
            "age" => results.first["age"].to_i,
            "home_id" => results.first["home_id"].to_i,
        }
    end

    def self.setHome(person_id, home)
        results = DB.exec(
            <<-SQL
                UPDATE people
                SET home_id = #{home.id}
                WHERE id = #{person_id}
                RETURNING id, name, age, home_id;
            SQL
        )
        return {
            "id" => results.first["id"].to_i,
            "name" => results.first["name"],
            "age" => results.first["age"].to_i,
            "home_id" => results.first["home_id"].to_i,
        }
    end
end