Generate dynamic hstore key calls in Prawn - ruby-on-rails-3

Question

I have an hstore column that I'm using to build a table in Prawn (pdf builder). The data will consist of records for a given month. Since it is hstore, the keys used will likely change from day to day so this needs to be dynamic.
I need to determine:
1 What unique keys are used that month
I created a helper to find the unique keys that were used in the month. These will be used as column headers.
keys(#users_logs)
# this returns an array like - ["XC", "PIC", "Mountain"]
The table will display a users dutylog data for the month. For testing...If I explicitly call known hstore keys...the data displays correctly. But, since its hstore...I wont know what the table column will be in production.
For testing, I call known hstore keys...this creates the prawn table row data per duty log.
#users_logs.map do |dutylog|
[ dutylog.properties["XC"],
dutylog.properties["PIC"],
dutylog.properties["Mountain"]
]
end
But, since this is hstore...I wont know what keys to call in production. So, I need to make the above iteration dynamic.
I tried, without success, to iterate over each dutylog entry, then iterate over each unique key and output one "dutylog.properties[x]" call for each key value...but, this just outputs the array of key values. I tried using send() in the block, but that didnt help.
#users_logs.map do |dutylog|
[ keys(#users_logs).each { |k| dutylog.properties[k] }.join(",") ]
end
Any ideas on how I could make the "dutylog.properties[k]" dynamic?

Answer 1

Took some head scratching...but turning out to be quit easy
This will build the rows for the Prawn table
def hstore_duty_log_rows
[keys(#users_logs)] +
#users_logs.map do |dutylog|
keys(#users_logs).map { |key| dutylog.properties.keys.include?(key) ? "#{dutylog.properties[key]}" : "0" }
end
end