= ruby_odata

The <b>Open Data Protocol</b> (OData) is a fantastic way to query and update data over standard Web technologies.  The ruby_odata library acts as a consumer of OData services.

== Resources

* Source Code (hosted on GitHub): http://github.com/visoft/ruby_odata 
* Documentation (hosted on rdoc.info): http://rdoc.info/projects/visoft/ruby_odata 
* Issue tracking (hosted on Lighthouse): http://visoft.lighthouseapp.com/projects/54309/home 
* Wiki (hosted on GitHub): http://wiki.github.com/visoft/ruby_odata/
* Gem (hosted on Gemcutter): http://gemcutter.org/gems/ruby_odata
* Blog articles: {Introducing a Ruby OData Client Library}[http://bit.ly/IntroRubyOData]

== Installation
You can install ruby_odata as a gem using:
	gem install ruby_odata

== Usage
As of version 0.0.5, support has been added for ActiveSupport 3.0.0 beta 4 and Ruby 1.9.1
As of version 0.0.6, support has been added for batch saves

=== Adding
When you point at a service, an AddTo<EntityName> method is created for you.  This method takes in the new entity to create.  To commit the change, you need to call the save_changes method on the service.  To add a new category for example, you would simply do the following:

	require 'lib/ruby_odata'
	
	svc = OData::Service.new "http://127.0.0.1:8888/SampleService/Entities.svc"
	new_category = Category.new
	new_category.Name = "Sample Category"
	svc.AddToCategories(new_category)
	category = svc.save_changes
	puts category.to_json

=== Updating
To update an object, simply pass the modified object to the update_object method on the service. Updating, like adding requires you to call save_changes in order to persist the change.  For example:

	require 'lib/ruby_odata'
		
	svc = OData::Service.new "http://127.0.0.1:8888/SampleService/Entities.svc"
	new_category = Category.new
	new_category.Name = "Sample Category"
	svc.AddToCategories(new_category)
	category = svc.save_changes
	puts category.to_json
	
	category.Name = 'Updated Category'
	svc.update_object(category)
	result = svc.save_changes
	puts "Was the category updated? #{result}"
	
=== Deleting
Deleting an object involves passing the tracked object to the delete_object method on the service.  Deleting is another function that involves the save_changes method (to commit the change back to the server).  In this example, we'll add a category and then delete it.

	require 'lib/ruby_odata'
	
	svc = OData::Service.new "http://127.0.0.1:8888/SampleService/Entities.svc"
	new_category = Category.new
	new_category.Name = "Sample Category"
	svc.AddToCategories(new_category)
	category = svc.save_changes
	puts category.to_json
	
	svc.delete_object(category)
	result = svc.save_changes
	puts "Was the category deleted? #{result}"

=== Querying
Querying is easy, for example to pull all the categories from the SampleService, you simply can run:

	require 'lib/ruby_odata'
	
	svc = OData::Service.new "http://127.0.0.1:8888/SampleService/Entities.svc"
	svc.Categories
	categories = svc.execute
	puts categories.to_json

You can also expand, add filters, order, skip records, and take only the top X records to the query before executing it.  For example:

=== Expanding
Expanding allows you to eagerly load other objects that are children of the root.
You can use more than one expand on a query.  
For expanding grandchild and lower entities, you must pass in the full path from the root, for example +Products.expand('Orders').expand('Orders/LineItems')+

	# Without expanding the query
	svc.Products(1)
	prod1 = svc.execute
	puts "Without expanding the query"
	puts "#{prod1.to_json}\n"
	
	# With expanding the query
	svc.Products(1).expand('Category')
	prod1 = svc.execute
	puts "Without expanding the query"
	puts "#{prod1.to_json}\n"


=== Filtering
The syntax for filtering can be found on the {OData Protocol URI Conventions}[http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption] page.
You can use more than one filter, if you call the filter method multiple times it will before an AND.

	# You can access by ID (but that isn't is a filter)
	# The syntax is just svc.ENTITYNAME(ID) which is shown in the expanding examples above
	
	svc.Products.filter("Name eq 'Product 2'")
	prod = svc.execute
	puts "Filtering on Name eq 'Product 2'"
	puts "#{prod.to_json}"
	
=== Combining Expanding and Filtering
The query operations follow a {fluent interface}[http://en.wikipedia.org/wiki/Fluent_interface], although they can be added by themselves as well as chained

	svc.Products.filter("Name eq 'Product 2'").expand("Category")
	prod = svc.execute
	puts "Filtering on Name eq 'Product 2' and expanding"
	puts "#{prod.to_json}"

=== Order By
You can order the results by properties of your choice, either ascending or descending.
Order by are similar to +expand+s in that you can use more than one of them on a query.
For expanding grandchild and lower entities, you must pass in the full path from the root like would do on an +expand+

	svc.Products.order_by("Name")
	products = svc.execute

	# Specifically requesting descending
	svc.Products.order_by("Name desc")
	products = svc.execute
	
	# Specifically requesting ascending
	svc.Products.order_by("Name asc")
	products = svc.execute
	
=== Skip
Skip allows you to skip a number of records when querying.  This is often used for paging along with +top+.
	
	svc.Products.skip(5)
	products = svc.execute # => skips the first 5 items 
	
=== Top
Top allows you only retrieve the top X number of records when querying.  This is often used for paging along with +skip+.
	
	svc.Products.top(5)
	products = svc.execute # => returns only the first 5 items	

== Tests
===DATABASE SETUP - DO THIS FIRST
Within /test/SampleService/App_Data/ rename _TestDB*.* to TestDB*.*. This file is just the initial database, and needs to be renamed so that unwanted changes to that DB aren't persisted in source control.

All of the tests are written using Cucumber going against a sample service (Found in /test/SampleService/*).  The SampleService is an ASP.NET Web Site running a SQLEXPRESS 2008 R2 Database (TestDB), as well as the ADO.NET Entity Framework and a WCF Data Service.  In order to run the tests, you need to spin up the SampleService and have it running on port 8888 (http://localhost:8888/SampleService).  

One way to do this is to open the SampleService within Visual Studio 2010 and run it from there.  Another option is to use Cassini (the built ASP.NET Development server that comes with Visual Studio 2010).  There is a batch file found in /test called "Cassini x64.bat", you can run the batch file and just close the command window. There is a also a "Cassini x86.bat" file for those of you running a 32-bit machine, however it hasn't been tested.  The only difference is the path to the Program Files directory.  Once you run the batch file, the web server will spin up and you can find the instance in your systray just like if Visual Studio ran it for you.  To stop the server, right click on the icon in your systray and tell it to stop