Using ActiveRecord without Rails

The library for working with ActiveRecord databases can also be used outside of Rails.

Task

Our test project will take the time of the rising of the moon with Yandex. Weather and save it to the database using ActiveRecord. At the same time we will look at working with Nokogiri (a good replacement for hpricot ).

Project structure

We will use migrations, the configuration file database.yaml, Rakefile, the sqlite database (development.sqlite3), in general, an environment close to our favorite rails.



View on github .

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Setting up a database connection and creating a table using migrations

For convenience, the configuration of the database connection is placed in a separate file lib / config / database.yml :

1. adapter: sqlite3
2. database: lib / db / development.sqlite3

And the connection to the database in lib / config / environment.rb :

1. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
2. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
3. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
5. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
6. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
8. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
9. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
11. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )
12. require 'rubygems' require 'active_record' require 'yaml' # dbconfig = YAML :: load ( File . open ( File . join ( File . dirname ( __FILE__ ) , 'database.yml' ) ) ) # () ActiveRecord::Base . logger = Logger . new ( STDERR ) # Simple logging utility. logger.rb -- standart lib # ActiveRecord::Base . establish_connection ( dbconfig )

Let's prepare the database migration for creating the table. For simplicity, it only has two string fields: day and time:

1. class CreateMoonRiseTimes < ActiveRecord :: Migration
2. def self . up
3. create_table : moon_rise_times do | t |
4. t. string : day
5. t. string : time
6. end
7. end
9. def self . down
10. drop_table : moon_rise_times
11. end
12. end

To perform the migration, create a rake file.

1. require 'lib / config / environment.rb'
3. Documentation on rake docs.rubyrake.org
4. # namespace - rake.rubyforge.org/classes/Rake/NameSpace.html
6. namespace : db do
7. desc "Migrate the database"
8. task : migrate do
9. # performing all migrations from lib / db / migrate,
10. # method takes parameters: migrate (migrations_path, target_version = nil)
11. # in our case
12. # migrations_path = lib / db / migrate
13. # target_version = ENV ["VERSION"]? ENV ["VERSION"]. To_i: nil
14. # migration starts as rake db: migrate VERSION = version_number
15. ActiveRecord :: Migrator . migrate ( 'lib / db / migrate' , ENV [ "VERSION" ] ? ENV [ "VERSION" ] . to_i : nil )
16. end
17. end

Let's migrate:

1. $ rake db: migrate version = 1
   
   
   
   
2. ( in / home / data / projects / ActiveRecord-without-Rails )
   
   
3. == CreateMoonRiseTimes: migrating ============================================
4. - create_table ( : moon_rise_times )
5. SQL ( 1.0ms ) CREATE TABLE "moon_rise_times" ( "id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "day" varchar ( 255 ) , "time" varchar ( 255 ) )
6. - > 0.0019s
7. == CreateMoonRiseTimes: migrated ( 0.0020s ) ===================================
8. SQL ( 0.1ms ) INSERT INTO schema_migrations ( version ) VALUES ( '1' )

Fine. Migration 001_create_moon_rise_times.rb created the moon_rise_times table with the day and time fields.

Extracting data and storing it in the database

Now you need to find some useful data to save to the database. For example, we will take from the site Yandeks.Pogoda time of the rising of the moon. You can also catch currency rates, news, the value of karma, etc ...



First of all, let's create a test file lib / test_search.rb that is looking for the necessary data on Yandex.Pagoda:

1. # A file with a small script for testing the work of nokogiri.
3. $ KCODE = "u"
4. require 'jcode'
5. require 'rubygems'
6. require 'open-uri'
7. require 'iconv'
8. require 'nokogiri'
11. # Download html document
12. source = open ( "pogoda.yandex.ru/26063/details/" )
14. # Create a nokogiri object from the loaded document
15. data = Nokogiri :: HTML ( source )
16. # Extract all html table rows using the search method and simple xpath expression
17. # wiki.github.com/tenderlove/nokogiri
20. = begin
21. Fragment of the source html-file, in which you need to find the date of the rising of the moon :)
23. <th class = "date" rowspan = "4"> <b title = ""> 9 </ b> <span> July </ span> </ th>
25. = end
27. data_html = data. search ( "th [@class = date] // b" ) . first . inner_html + "" + data. search ( "th [@class = date] // span" ) . first . inner_html
28. puts data_html
30. = begin
31. A fragment of the source html file, in which you need to find the time of the rising of the moon on the day defined above :)
33. <td class = "dawn-dark" rowspan = "4">
34. <dl>
35. <dt> Sunrise </ dt>
36. <dd> 04:52 </ dd>
37. <dt> Sunset </ dt>
38. <dd> 23:15 </ dd>
39. </ dl>
40. <img src = "// i.yandex.st/weather/i/moon/07.gif" alt = "The Waning Moon" title = "The Waning Moon">
41. </ td>
43. = end
45. time_html = data. search ( "td [@class = dawn-dark] // dl // dd" ) . first . inner_html
46. puts time_html

We get:

1. $ ruby ​​lib / test_search.rb
2. July 10
3. 04: 53

Ok, what we need.

Now you need to save the data in the database. There is a create method for this in ActiveRecord :: Base



The file that does the main work, lib / main.rb:

1. $ KCODE = "u"
2. require 'jcode'
3. require 'rubygems'
4. require 'active_record'
5. require 'yaml'
6. require 'logger'
7. require 'open-uri'
8. require 'iconv'
9. require 'nokogiri'
12. # load the environment.rb file settings and connect to the database
13. require file . join ( File . dirname ( __FILE__ ) , 'config / environment.rb' )
15. # Create a MoonRiseTime class that wraps the moon_rise_times table
16. # Table cells: day - data type, rise_times - time type
17. #
19. class MoonRiseTime < ActiveRecord :: Base
20. end
22. MoonRiseTime. create do | moon_rise_time |
23. # Download html document
24. source = open ( "pogoda.yandex.ru/26063/details/" )
26. # Create a nokogiri object from the loaded document
27. data = Nokogiri :: HTML ( source )
28. # Extract all html table rows using the search method and simple xpath expression
29. # nokogiri.org/Nokogiri/XML/Node.html#method-i-inner_html
31. #: TODO: Cast data types to data and time
32. # Find the original html date
33. data_moon_rise = data. search ( "th [@class = date] // b" ) . first . inner_html
34. month_moon_rise = data. search ( "th [@class = date] // span" ) . first . inner_html
36. # pass the data found to the methods of the database wrapper class
37. moon_rise_time. day = data_moon_rise + "" + month_moon_rise
39. moon_rise_time. time = data. search ( "td [@class = dawn-dark] // dl // dd" ) . first . inner_html
40. end

Run it:

1. ruby lib / main.rb
2. MoonRiseTime Create ( 0.4ms ) INSERT INTO "moon_rise_times" ( "time" , "day" ) VALUES ( '04: 53 ' , '10 July' )

It feels good.



Let's see what was saved in the database using a small script lib / test_fetch_data.rb :

1. # File with a small script for testing
2. # extracting data from the moon_rise_times table.
4. # load the configuration file and connect to the database in the file environment.rb
5. require file . join ( File . dirname ( __FILE__ ) , 'config / environment.rb' )
7. # Create a MoonRiseTime class that wraps the moon_rise_times table
8. # Table cells: day, time - type string
10. class MoonRiseTime < ActiveRecord :: Base
11. end
13. # Extract all records from the database in fetch_result
14. fetch_result = MoonRiseTime. all
16. # Displaying fetch_result
17. fetch_result. each do | result_item |
18. puts result_item. id
19. puts result_item. time
20. puts result_item. day
21. end

Conclusion:

1. $ ruby ​​lib / test_fetch_data.rb
2. MoonRiseTime Load ( 0.5ms ) SELECT * FROM "moon_rise_times"
3. one
4. 04: 53
5. July 10

OK! Now, starting our program every day, you can follow the time of the moon rising!

Used materials

• http://blog.aizatto.com/2007/05/21/activerecord-without-rails/
• http://blog.aizatto.com/2007/05/27/activerecord-migrations-without-rails/
• http://en.wikibooks.org/wiki/Ruby_on_Rails/ActiveRecord/Migrations