The Open Data Protocol (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.
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Source Code (hosted on GitHub): github.com/visoft/ruby_odata
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Documentation (hosted on rdoc.info): rdoc.info/projects/visoft/ruby_odata
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Issue tracking (hosted on GitHub): github.com/visoft/ruby_odata/issues
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Wiki (hosted on GitHub): wiki.github.com/visoft/ruby_odata/
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Gem (hosted on Gemcutter): gemcutter.org/gems/ruby_odata
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Blog articles:
You can install ruby_odata as a gem using:
gem install ruby_odata
There are various options that you can pass when creating an instance of the service, these include:
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username: username for http basic auth
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password: password for http basic auth
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verify_ssl: false if no verification, otherwise mode (OpenSSL::SSL::VERIFY_PEER is default)
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additional_params: a hash of query string params that will be passed on all calls (query, new, update, delete, batch)
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 'ruby_odata' svc = OData::Service.new "http://127.0.0.1:8989/SampleService/Entities.svc" new_category = Category.new new_category.Name = "Sample Category" svc.AddToCategories(new_category) category = svc.save_changes puts category.to_json
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 'ruby_odata' svc = OData::Service.new "http://127.0.0.1:8989/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 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 'ruby_odata' svc = OData::Service.new "http://127.0.0.1:8989/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 is easy, for example to pull all the categories from the SampleService, you simply can run:
require 'ruby_odata' svc = OData::Service.new "http://127.0.0.1:8989/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 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"
The syntax for filtering can be found on the OData Protocol URI Conventions 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}"
Note you can pass more than one filter in the string, for example (querying Netflix):
svc.Titles.filter("Rating eq 'PG' and ReleaseYear eq 1980")
Filters can also be chained, by doing this you will create an “and” filter (just like the last example) when it is passed to the server.
svc.Titles.filter("Rating eq 'PG'").filter("ReleaseYear eq 1980")
The query operations follow a 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}"
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
Like the fiter method, order_by statements can also be chained like so:
svc.Products.order_by("Name asc").order_by("Price desc")
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 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
Basic HTTP Authentication is supported via sending a username and password as service constructor arguments:
require 'ruby_odata' svc = OData::Service.new "http://127.0.0.1:8989/SampleService/Entities.svc", { :username => "bob", :password=> "12345" }
The certificate verification mode can be passed in the options hash via the :verify_ssl key. For example, to ignore verification in order to use a self-signed certificate:
require 'ruby_odata' svc = OData::Service.new "https://127.0.0.1:44300/SampleService/Entities.svc", { :verify_ssl => false }
Or an OpenSSL integer constant can be passed as well:
require 'ruby_odata' svc = OData::Service.new "https://127.0.0.1:44300/SampleService/Entities.svc", { :verify_ssl => OpenSSL::SSL::VERIFY_PEER }
Default verification is OpenSSL::SSL::VERIFY_PEER. Note due to the way Ruby’s Request object implements certificate checking, you CAN NOT pass OpenSSL::SSL::VERIFY_NONE, you must instead pass a boolean false.
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 8989 (localhost:8989/SampleService).
One way to do this is to open the SampleService within Visual Studio 2010 and run it from there (must use IIS instead of development web server in order for basic auth tests to pass, however). Another option is to use IIS Express. It is a free download from Microsoft. Once installed, there is a batch file found in /test called “iisExpress x64.bat”, you can run the batch file and just close the command window. There is a also an “iisExpress x86.bat” file for those of you running a 32-bit machine. 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.
Note there are also Cassini batch files that you can use as well, but the basic auth tests will fail if using this server (which doesn’t support basic http authentication).
If you are testing on a Windows machine, you may encounter a problem with using cucumber and Ruby 1.9.2. You will get a message when you fire up cucumber about missing msvcrt-ruby18.dll. The fix for this is to make sure you have the RubyInstaller DevKit installed, then do the following:
gem uninstall json gem install json --platform=ruby -v 1.4.6
From the BASE ruby_odata directory, run cucumber, which will execute all of the tests.