Added support for querying links

CHANGELOG.rdoc

@@ -72,4 +72,5 @@
 
 === 0.1.0
 * New Features
-  * Added support for single layer inheritance (thanks to http://odetocode.com/Blogs/scott/archive/2010/07/11/odata-and-ruby.aspx)
+  * Added support for single layer inheritance (thanks to http://odetocode.com/Blogs/scott/archive/2010/07/11/odata-and-ruby.aspx)
+  * Added support for querying links (see https://github.com/visoft/ruby_odata/issues/10)

README.rdoc

@@ -165,6 +165,11 @@ Top allows you only retrieve the top X number of records when querying.  This is
   svc.Products.top(5)
   products = svc.execute # => returns only the first 5 items	
 
+=== Navigation Property Links Only Query
+OData allows you to {query navigation properties and only return the links for the entities}[http://www.odata.org/developers/protocols/uri-conventions#AddressingLinksBetweenEntries] (instead of the data)
+  svc.Categories(1).links("Products")
+  product_links = svc.execute # => returns URIs for the products under the Category with an ID of 1
+
 === Partial feeds
 OData allows services to do server-side paging in Atom by defining a next link. The default behavior is to repeatedly consume partial feeds until the result set is complete.
 

features/query_builder.feature

@@ -146,8 +146,18 @@ Scenario: Top should be able to be used along with skip for paging
   | Product 4 |  
 
 
-
-
-
-
-
+# Links
+@current
+Scenario: Navigation Properties should be able to represented as links
+  Given I call "AddToCategories" on the service with a new "Category" object with Name: "Test Category"
+  And I save changes
+  And the following Products exist:
+  | Name      | Category         |
+  | Product 1 | @@LastSave.first |
+  | Product 2 | @@LastSave.first |
+  | Product 3 | @@LastSave.first |
+  When I call "Categories" on the service with args: "1"
+  And I ask for the links for "Products"
+  And I run the query
+  Then the result count should be 3
+  Then the method "path" on the result object should equal: "/SampleService/Entities.svc/Products(1)"

features/step_definitions/service_steps.rb

@@ -9,6 +9,45 @@ def first(results)
 BASICAUTH_URL = "http://#{WEBSERVER}:#{HTTP_PORT_NUMBER}/SampleService/BasicAuth/Entities.svc"
 HTTPS_BASICAUTH_URL = "https://#{WEBSERVER}:#{HTTPS_PORT_NUMBER}/SampleService/BasicAuth/Entities.svc"
 
+# Helper methods
+def handle_last_save_fields(val)
+  if val =~ /^@@LastSave.first$/
+    val = @saved_result.first
+  end
+  if val =~ /^@@LastSave$/
+    val = @saved_result
+  end
+  val
+end
+
+def parse_fields_string(fields)
+  fields_hash = {}
+
+  if !fields.nil?
+    fields.split(', ').each do |field|
+      if field =~ /^(?:(\w+): "(.*)")$/
+        key = $1
+        val = handle_last_save_fields($2)
+
+        fields_hash.merge!({key => val})
+      end
+    end
+  end
+  fields_hash
+end
+
+def parse_fields_hash(fields)
+  fields_hash = {}
+
+  if !fields.nil?
+    fields.each do |key, val|        
+      val = handle_last_save_fields(val)
+      fields_hash.merge!({key => val})
+    end
+  end
+  fields_hash
+end
+
 When /^(.*) first (.*)$/ do |step, results|
   first(results) { When step }
 end
@@ -89,6 +128,10 @@ def first(results)
   @service_result.send(method.to_sym).to_s.should == value
 end
 
+Then /^the method "([^\"]*)" on the result object should equal: "([^\"]*)"$/ do |method, value|
+  @service_result.first.send(method.to_sym).to_s.should == value
+end
+
 Then /^the method "([^\"]*)" on the result should be nil$/ do |method|
   @service_result.send(method.to_sym).should == nil
 end
@@ -121,30 +164,17 @@ def first(results)
   @service_query.top(top)
 end
 
+When /^I ask for the links for "([^\"]*)"$/ do |nav_prop|
+  @service_query.links(nav_prop)
+end
+
 Then /^the method "([^\"]*)" on the result should be of type "([^\"]*)"$/ do |method, type|
   result = @service_result.send(method.to_sym) 
   result.class.to_s.should == type
 end
 
 Given /^I call "([^\"]*)" on the service with a new "([^\"]*)" object(?: with (.*))?$/ do |method, object, fields|
-  fields_hash = {}
-
-  if !fields.nil?
-    fields.split(', ').each do |field|
-      if field =~ /^(?:(\w+): "(.*)")$/
-        key = $1
-        val = $2
-        if val =~ /^@@LastSave.first$/
-          val = @saved_result.first
-        end
-        if val =~ /^@@LastSave$/
-          val = @saved_result
-        end
-
-        fields_hash.merge!({ key => val })
-      end
-    end	
-  end
+  fields_hash = parse_fields_string(fields)
 
   obj = object.constantize.send(:make, fields_hash)
   @service.send(method.to_sym, obj)
@@ -197,11 +227,12 @@ def first(results)
   results.should == []
 end
 
+
 Given /^the following (.*) exist:$/ do |plural_factory, table|
   # table is a Cucumber::Ast::Table
   factory = plural_factory.singularize
   table.hashes.map do |hash|
-    obj = factory.constantize.send(:make, hash)
+    obj = factory.constantize.send(:make, parse_fields_hash(hash))
     @service.send("AddTo#{plural_factory}", obj)
     @service.save_changes
   end
@@ -326,4 +357,12 @@ def first(results)
   else
     @service_result.send(methods[0]).send(methods[1]).xmlschema(3).should == @stored_query_result.send(methods[0]).send(methods[1]).xmlschema(3)
   end
+end
+
+Then /^show me the results$/ do
+  puts @service_result
+end
+
+Then /^the result count should be (\d+)$/ do |expected_count|
+  @service_result.count.should eq expected_count.to_i
 end

lib/ruby_odata/query_builder.rb

@@ -19,6 +19,7 @@ def initialize(root, additional_params = {})
     @order_bys = []
     @skip = nil
     @top = nil
+    @links = nil
     @additional_params = additional_params
   end
 
@@ -89,10 +90,28 @@ def top(num)
     self
   end
 
+  # Used to return links instead of actual objects
+  # ==== Required Attributes
+  # - navigation_property: The NavigationProperty name to retrieve the links for
+  #
+  # ==== Example	
+  # 	svc.Categories(1).links("Products")
+  # 	product_links = svc.execute # => returns URIs for the products under the Category with an ID of 1
+  def links(navigation_property)
+    @navigation_property = navigation_property
+    self
+  end
+
   # Builds the query URI (path, not including root) incorporating expands, filters, etc.
   # This is used internally when the execute method is called on the service
   def query
     q = @root.clone
+
+    # Handle links queries, this isn't just a standard query option
+    if @navigation_property
+      q << "/$links/#{@navigation_property}"
+    end
+
     query_options = []
     query_options << "$expand=#{@expands.join(',')}" unless @expands.empty?
     query_options << "$filter=#{@filters.join('+and+')}" unless @filters.empty?

lib/ruby_odata/service.rb

@@ -223,6 +223,10 @@ def collect_properties(klass_name, edm_ns, element, doc)
   # Helper to loop through a result and create an instance for each entity in the results
   def build_classes_from_result(result)
     doc = Nokogiri::XML(result)
+
+    is_links = doc.at_xpath("/ds:links", "ds" => "http://schemas.microsoft.com/ado/2007/08/dataservices")
+    return parse_link_results(doc) if is_links
+
     entries = doc.xpath("//atom:entry[not(ancestor::atom:entry)]", "atom" => "http://www.w3.org/2005/Atom")
 
     extract_partial(doc)
@@ -320,7 +324,17 @@ def handle_partial
     end
     results
   end
-
+
+  # Handle link results
+  def parse_link_results(doc)
+    uris = doc.xpath("/ds:links/ds:uri", "ds" => "http://schemas.microsoft.com/ado/2007/08/dataservices")
+    results = []
+    uris.each do |uri_el|
+      link = uri_el.content
+      results << URI.parse(link)
+    end
+    results
+  end   
 
   # Build URIs
   def build_metadata_uri

spec/fixtures/edmx_categories_products.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="iso-8859-1" standalone="yes"?>
+<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
+  <edmx:DataServices xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" m:DataServiceVersion="1.0">
+    <Schema Namespace="Model" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://schemas.microsoft.com/ado/2008/09/edm">
+      <EntityContainer Name="ModelContainer" p7:LazyLoadingEnabled="true" m:IsDefaultEntityContainer="true" xmlns:p7="http://schemas.microsoft.com/ado/2009/02/edm/annotation">
+        <FunctionImport Name="CleanDatabaseForTesting" m:HttpMethod="POST" />
+        <EntitySet Name="Products" EntityType="Model.Product" />
+        <EntitySet Name="Categories" EntityType="Model.Category" />
+        <AssociationSet Name="CategoryProduct" Association="Model.CategoryProduct">
+          <End Role="Category" EntitySet="Categories" />
+          <End Role="Product" EntitySet="Products" />
+        </AssociationSet>
+      </EntityContainer>
+      <EntityType Name="Product">
+        <Key>
+          <PropertyRef Name="Id" />
+        </Key>
+        <Property Name="Id" Type="Edm.Int32" Nullable="false" p8:StoreGeneratedPattern="Identity" xmlns:p8="http://schemas.microsoft.com/ado/2009/02/edm/annotation" />
+        <Property Name="Name" Type="Edm.String" Nullable="false" />
+        <Property Name="Description" Type="Edm.String" Nullable="false" />
+        <Property Name="Price" Type="Edm.Decimal" Nullable="false" />
+        <Property Name="AuditFields" Type="Model.AuditFields" Nullable="false" />
+        <Property Name="DiscontinuedDate" Type="Edm.DateTime" Nullable="true" />
+        <NavigationProperty Name="Category" Relationship="Model.CategoryProduct" FromRole="Product" ToRole="Category" />
+      </EntityType>
+      <ComplexType Name="AuditFields">
+        <Property Name="CreateDate" Type="Edm.DateTime" Nullable="false" />
+        <Property Name="ModifiedDate" Type="Edm.DateTime" Nullable="false" />
+        <Property Name="CreatedBy" Type="Edm.String" Nullable="true" />
+      </ComplexType>
+      <EntityType Name="Category">
+        <Key>
+          <PropertyRef Name="Id" />
+        </Key>
+        <Property Name="Id" Type="Edm.Int32" Nullable="false" p8:StoreGeneratedPattern="Identity" xmlns:p8="http://schemas.microsoft.com/ado/2009/02/edm/annotation" />
+        <Property Name="Name" Type="Edm.String" Nullable="false" />
+        <NavigationProperty Name="Products" Relationship="Model.CategoryProduct" FromRole="Category" ToRole="Product" />
+      </EntityType>
+      <Association Name="CategoryProduct">
+        <End Role="Category" Type="Model.Category" Multiplicity="1" />
+        <End Role="Product" Type="Model.Product" Multiplicity="*" />
+      </Association>
+    </Schema>
+  </edmx:DataServices>
+</edmx:Edmx>

spec/fixtures/links/result_links_query.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="iso-8859-1" standalone="yes"?>
+<links xmlns="http://schemas.microsoft.com/ado/2007/08/dataservices">
+  <uri>http://test.com/SampleService/Entities.svc/Products(1)</uri>
+  <uri>http://test.com/SampleService/Entities.svc/Products(2)</uri>
+  <uri>http://test.com/SampleService/Entities.svc/Products(3)</uri>    
+</links>

spec/query_builder_spec.rb

@@ -18,6 +18,17 @@ module OData
         builder.top(10)
         builder.query.should eq "Products?$top=10&x=1&y=2"
       end
+      it "should properly handle queries for links" do
+        builder = QueryBuilder.new 'Categories(1)'
+        builder.links('Products')
+        builder.query.should eq "Categories(1)/$links/Products"
+      end
+      it "should properly handle queries for links with additional operations" do
+        builder = QueryBuilder.new 'Categories(1)'
+        builder.links('Products')
+        builder.top(5)
+        builder.query.should eq "Categories(1)/$links/Products?$top=5"
+      end
     end
   end
 end