Understanding Ruby script for cassandra database - ruby-on-rails

Question

I am a Ruby novice. But due to some problem I have to handle the code as our ruby developer is not available. We are using cassandra database to get values from a Ruby (Sinatra) web service and put it into the Cassandra keyspace. But due to some problem , the data is failing to insert.
In the following code partners_daily , partner_monthly etc are column family (tables) in the stats keyspace(database).
if params and !partner_id.nil? and !activity_type.nil?
{
:partners_daily => "#{partner_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}_#{time.day}",
:partners_monthly => "#{partner_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}",
:partners_alltime => "#{partner_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}",
:channels_daily => "#{channel_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}_#{time.day}",
:channels_monthly => "#{channel_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}",
:channels_alltime => "#{channel_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}",
:countries_daily => "#{country}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}_#{time.day}",
:countries_monthly => "#{country}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}",
:countries_alltime => "#{country}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}"
}.each do |k,v|
stats.add(k, v, 1, 'count')
end
return "Activity stored in stats"
end
else
return "Error: client headers missing"
end
end
def count(table, key)
require 'cassandra-cql' # requiring this at the top was leading to error: unconfigured columnfamily
cqldb = CassandraCQL::Database.new('127.0.0.1:9160', {:keyspace => 'plystats'})
query = "update partners_daily set count = ? where key = ?"#"update #{table} set count = count+1 where key = ?;"
#return cqldb.execute(query, 0, 'sonia').inspect
return query
end
I want to know how the data inserting logic in it is being performed, and where ? Is it in stats.add(k, v, 1, 'count') ?
and is there any error in the inserting part because its failing.

Answer 1

I want to know how the data inserting logic in it is being performed, and where ? Is it in stats.add(k, v, 1, 'count') ?
Yes, that's where it should be happening. Between the {} are dictionary/hash values:
{
:partners_daily => # …
}.each do |k,v|
A loop is started with the each method, and each entry is decomposed and put into k and v, the key in k and the value in v. For example, the first record in the hash is:
:partners_daily => "#{partner_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}_#{time.day}",
This would then decompose within the each loop to:
k = :partners_daily
v = # The result of
"#{partner_id}_#{activity_type}_#{success == 1 ? 'sucess' : "failure:#{failure_code}"}_#{time.year}_#{time.month}_#{time.day}",
I don't now what the values are for partner_id etc, but making some up it'd look something like "123_sales_sucess_2013_6_01"
Notice there's a typo for the word success in there.
It's a bit confusing due to the multiple double quotes and braces, so I'd change this to:
[partner_id, activity_type, (success == 1 ? 'success' : "failure:#{failure_code}"), time.year, time.month, time.day].join("_")
But notice that there's a lot of repetition in there, so I'd change the whole hash to (at least):
success_string = success == 1 ?
'success' :
"failure:#{failure_code}"
data = {
:partners_daily => [partner_id, activity_type,success_string,time.year,time.month,time.day].join("_"),
:partners_monthly => [partner_id,activity_type,success_string,time.year,time.month].join("_"),
:partners_alltime => [partner_id,activity_type,success_string].join("_"),
:channels_daily => [channel_id,activity_type,success_string,time.year,time.month,time.day].join("_"),
:channels_monthly => [channel_id,activity_type,success_string,time.year,time.month].join("_"),
:channels_alltime => [channel_id,activity_type,success_string].join("_"),
:countries_daily => [country,activity_type,success_string,time.year,time.month,time.day].join("_"),
:countries_monthly => [country,activity_type,success_string,time.year,time.month].join("_"),
:countries_alltime => [country,activity_type,success_string].join("_")
}
data.each do |k,v|
# more code…
It starts to be easier to read and see the logic. Also, by putting the hash into the data variable instead of working on it immediately, it allows you to inspect it more easily, e.g.
warn "data = #{data.inspect}"
would output a representation of the data to the console, so at least you could get an idea of what the script is attempting to put in. At the top of this code, you could also add warn "script = #{script.inspect}" to check what the script object looks like.
If the script object is a Cassandra instance i.e. there's something like script = Cassandra.new "blah", "blahblah" that sets it up, then the add method is this one
The signature given is add(column_family, key, value, *columns_and_options) but that doesn't seem to match the call you have:
stats.add(k, v, 1, 'count')
should (probably) be:
stats.add('count', k, v, 1)
In fact, I'm not even sure that the concatenation in the data hash should happen and maybe all of that should just be passed to add, but it's your data so I can't be sure.
Feel free to comment below and I'll update this.
Trying it in IRB to check it for syntax errors:
success = 1
# => 1
partner_id = 123
# => 123
activity_type = "something"
# => "something"
time = Time.now
# => 2013-06-05 11:17:50 0100
channel_id = 456
# => 456
country = "UK"
# => "UK"
success_string = success == 1 ?
'success' :
"failure:#{failure_code}"
# => "success"
data = {
:partners_daily => [partner_id, activity_type,success_string,time.year,time.month,time.day].join("_"),
:partners_monthly => [partner_id,activity_type,success_string,time.year,time.month].join("_"),
:partners_alltime => [partner_id,activity_type,success_string].join("_"),
:channels_daily => [channel_id,activity_type,success_string,time.year,time.month,time.day].join("_"),
:channels_monthly => [channel_id,activity_type,success_string,time.year,time.month].join("_"),
:channels_alltime => [channel_id,activity_type,success_string].join("_"),
:countries_daily => [country,activity_type,success_string,time.year,time.month,time.day].join("_"),
:countries_monthly => [country,activity_type,success_string,time.year,time.month].join("_"),
:countries_alltime => [country,activity_type,success_string].join("_")
}
# => {:partners_daily=>"123_something_success_2013_6_5", :partners_monthly=>"123_something_success_2013_6", :partners_alltime=>"123_something_success", :channels_daily=>"456_something_success_2013_6_5", :channels_monthly=>"456_something_success_2013_6", :channels_alltime=>"456_something_success", :countries_daily=>"UK_something_success_2013_6_5", :countries_monthly=>"UK_something_success_2013_6", :countries_alltime=>"UK_something_success"}