Base.exists?(id, options) and Base#exists? check whether the resource is found. Closes #6970.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5898 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 38 insertions, 0 deletions

diff --git a/activeresource/CHANGELOG b/activeresource/CHANGELOG
index 3a2d70c387..44108fb8ce 100644
--- a/activeresource/CHANGELOG
+++ b/activeresource/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Base.exists?(id, options) and Base#exists? check whether the resource is found.  #6970 [rwdaigle]
+
 * Query string support.  [untext, Jeremy Kemper]
     # GET /forums/1/topics.xml?sort=created_at
     Topic.find(:all, :forum_id => 1, :sort => 'created_at')
diff --git a/activeresource/lib/active_resource/base.rb b/activeresource/lib/active_resource/base.rb
index 7f99e5cbf5..8babc18507 100644
--- a/activeresource/lib/active_resource/base.rb
+++ b/activeresource/lib/active_resource/base.rb
@@ -80,6 +80,13 @@ module ActiveResource
         connection.delete(element_path(id))
       end
 
+      # True if the resource is found.
+      def exists?(id, options = {})
+        id && !find_single(id, options).nil?
+      rescue ActiveResource::ResourceNotFound
+        false
+      end
+
       private
         def find_every(options)
           collection = connection.get(collection_path(options)) || []
@@ -167,6 +174,11 @@ module ActiveResource
       connection.delete(element_path)
     end
 
+    # True if this resource is found.
+    def exists?
+      !new? && self.class.exists?(id, prefix_options)
+    end
+
     def to_xml(options={})
       attributes.to_xml({:root => self.class.element_name}.merge(options))
     end
diff --git a/activeresource/test/base_test.rb b/activeresource/test/base_test.rb
index a8c9454476..f9f2b24c72 100644
--- a/activeresource/test/base_test.rb
+++ b/activeresource/test/base_test.rb
@@ -21,6 +21,8 @@ class BaseTest < Test::Unit::TestCase
       mock.get    "/people.xml",               {}, "<people>#{@matz}#{@david}</people>"
       mock.get    "/people/1/addresses.xml",   {}, "<addresses>#{@addy}</addresses>"
       mock.get    "/people/1/addresses/1.xml", {}, @addy
+      mock.get    "/people/1/addresses/2.xml", {}, nil, 404
+      mock.get    "/people/2/addresses/1.xml", {}, nil, 404
       mock.put    "/people/1/addresses/1.xml", {}, nil, 204
       mock.delete "/people/1/addresses/1.xml", {}, nil, 200
       mock.post   "/people/1/addresses.xml",   {}, nil, 201, 'Location' => '/people/1/addresses/5'
@@ -237,4 +239,26 @@ class BaseTest < Test::Unit::TestCase
   def test_delete
     assert Person.delete(1)
   end
+
+  def test_exists
+    # Class method.
+    assert !Person.exists?(nil)
+    assert Person.exists?(1)
+    assert !Person.exists?(99)
+
+    # Instance method.
+    assert !Person.new.exists?
+    assert Person.find(1).exists?
+    assert !Person.new(:id => 99).exists?
+
+    # Nested class method.
+    assert StreetAddress.exists?(1, :person_id => 1)
+    assert !StreetAddress.exists?(1, :person_id => 2)
+    assert !StreetAddress.exists?(2, :person_id => 1)
+
+    # Nested instance method.
+    assert StreetAddress.find(1, :person_id => 1).exists?
+    assert !StreetAddress.new({:id => 1}, {:person_id => 2}).exists?
+    assert !StreetAddress.new({:id => 2}, {:person_id => 1}).exists?
+  end
 end