Added Utility Methods to Aws::Record Model Interface

lib/aws-record/record/attributes.rb

@@ -56,6 +56,19 @@ def to_h
         @data.hash_copy
       end
 
+      # Returns a string representation of the key attributes
+      #
+      # @return [String] String of key attributes that can be used to query a model
+      def to_param
+        hkey = public_send(self.class.hash_key)
+        if self.class.range_key
+          rkey = public_send(self.class.range_key)
+          "#{hkey}:#{rkey}"
+        else
+          "#{hkey}"
+        end
+      end
+
       module ClassMethods
 
         # Define an attribute for your model, providing your own attribute type.

lib/aws-record/record/dirty_tracking.rb

@@ -135,6 +135,18 @@ def dirty?
         @data.dirty?
       end
 
+      def persisted?
+        @data.persisted?
+      end
+
+      def new_record?
+        @data.new_record?
+      end
+
+      def destroyed?
+        @data.destroyed?
+      end
+
       # Fetches attributes for this instance of an item from Amazon DynamoDB 
       # using its primary key and the +find(*)+ class method.
       #

lib/aws-record/record/item_collection.rb

@@ -97,6 +97,7 @@ def _build_items_from_response(items, model)
             data.set_attribute(name, attr.extract(item))
           end
           data.clean!
+          data.new_record = false
           ret << record
         end
         ret

lib/aws-record/record/item_data.rb

@@ -23,8 +23,13 @@ def initialize(model_attributes, opts)
         @model_attributes = model_attributes
         @track_mutations = opts[:track_mutations]
         @track_mutations = true if opts[:track_mutations].nil?
+        @new_record = true
+        @destroyed = false
+
         populate_default_values
       end
+
+      attr_accessor :new_record, :destroyed
 
       def get_attribute(name)
         @model_attributes.attribute_for(name).type_cast(@data[name])
@@ -34,6 +39,18 @@ def set_attribute(name, value)
         @data[name] = value
       end
 
+      def new_record?
+        @new_record
+      end
+
+      def destroyed?
+        @destroyed
+      end
+
+      def persisted?
+        !(new_record? || destroyed?)
+      end
+
       def raw_value(name)
         @data[name]
       end

lib/aws-record/record/item_operations.rb

@@ -81,6 +81,24 @@ def save(opts = {})
         end
       end
 
+
+      # Performs mass assignment of model attributes
+      def assign_attributes(opts)
+        opts.each do |field, new_value|
+          if !respond_to?("#{field}=")
+            raise ArgumentError.new "Invalid field: #{field} for model"
+          end
+          @data.set_attribute field, new_value
+        end
+      end
+
+      # Updates model attributes and then performs a conditional save
+      def update(opts)
+        self.assign_attributes opts
+
+        self.save
+      end
+
       # Deletes the item instance that matches the key values of this item
       # instance in Amazon DynamoDB. Uses the
       # {http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html#delete_item-instance_method Aws::DynamoDB::Client#delete_item}
@@ -90,7 +108,7 @@ def delete!
           table_name: self.class.table_name,
           key: key_values
         )
-        true
+        self.instance_variable_get("@data").destroyed = true
       end
 
       private
@@ -151,6 +169,10 @@ def _perform_save(opts)
             )
           end
         end
+        data = self.instance_variable_get("@data")
+        data.destroyed = false if data.destroyed
+        data.new_record = false if data.new_record
+        true
       end
 
       def _build_item_for_save

spec/aws-record/record/attributes_spec.rb

@@ -150,6 +150,22 @@ module Record
           item.clever = "No problem."
           expect(item.to_h).to eq({ clever: "No problem." })
         end
+
+        it 'should provide a parametrized representation of the hash key' do
+          klass.string_attr(:mykey, hash_key: true)
+          item = klass.new
+          item.mykey = "test_key"
+          expect(item.to_param).to eq("test_key")
+        end
+
+        it 'should provide a parametrized representation of hash and range keys' do
+          klass.string_attr(:mykey, hash_key: true)
+          klass.string_attr(:myrkey, range_key: true)
+          item = klass.new
+          item.mykey = "test_key"
+          item.myrkey = "test_range_key"
+          expect(item.to_param).to eq("test_key:test_range_key")
+        end
       end
 
     end

spec/aws-record/record/dirty_tracking_spec.rb

@@ -188,6 +188,30 @@
 
   end
 
+  describe "persisted?" do
+    before(:each) do 
+      klass.configure_client(client: stub_client)
+    end
+
+    it "appropriately determines whether an item is persisted" do
+      item = klass.new
+      item.mykey = SecureRandom.uuid
+      item.body = SecureRandom.uuid
+
+      # Test all combinations of new_recorded and destroyed
+      expect(item.persisted?).to be false
+      item.save
+      expect(item.persisted?).to be true
+      item.delete!
+      expect(item.persisted?).to be false
+      item = klass.new
+      item.mykey = SecureRandom.uuid
+      item.body = SecureRandom.uuid
+      item.delete!
+      expect(item.persisted?).to be false
+    end
+  end
+
   describe '#rollback_[attribute]!' do 
 
     it "should restore the attribute to its last known clean value" do 
@@ -236,6 +260,39 @@
 
   end
 
+  describe "#update" do
+
+    before(:each) do 
+      klass.configure_client(client: stub_client)
+    end
+
+    it 'should perform a hash based attribute assignment without persisting changes' do
+      item = klass.new
+      item.mykey = SecureRandom.uuid
+      item.body = SecureRandom.uuid
+      item.save
+
+      new_key = SecureRandom.uuid
+      new_body = SecureRandom.uuid
+      item.assign_attributes :mykey => new_key, :body => new_body
+      expect(item.mykey).to eq new_key
+      expect(item.body).to eq new_body
+      expect(item.dirty?).to be true
+    end
+
+    it 'should throw an argument error when you try to update an invalid attribute' do
+      item = klass.new
+      item.mykey = SecureRandom.uuid
+      item.body = SecureRandom.uuid
+      item.save
+
+      expect {
+        item.assign_attributes :mykey_key => SecureRandom.uuid
+      }.to raise_error(ArgumentError)
+    end
+
+  end
+
   describe "#save" do 
 
     before(:each) do 

spec/aws-record/record/item_collection_spec.rb

@@ -77,6 +77,23 @@ module Record
         end
       end
 
+      describe "#new_record" do
+        it 'marks records fetched from a client call as not being new' do
+          stub_client.stub_responses(:scan, non_truncated_resp)
+          c = ItemCollection.new(
+            :scan,
+            { table_name: "TestTable" },
+            model,
+            stub_client
+          )
+
+          c.each do |record|
+            expect(record.new_record?).to eq false
+            expect(record.destroyed?).to be false
+          end
+        end
+      end
+
       describe "#last_evaluated_key" do
         it "points you to the client response pagination value if present" do
           stub_client.stub_responses(:scan, truncated_resp)

spec/aws-record/record/item_operations_spec.rb

@@ -104,7 +104,9 @@ module Record
           item.id = 1
           item.date = '2015-12-14'
           item.body = 'Hello!'
+          expect(item.new_record?).to be(true)
           item.save
+          expect(item.new_record?).to be(false)
           expect(api_requests).to eq([{
             table_name: "TestTable",
             item: {
@@ -420,6 +422,7 @@ module Record
           item.id = 3
           item.date = "2015-12-17"
           expect(item.delete!).to be(true)
+          expect(item.destroyed?).to be(true)
           expect(api_requests).to eq([{
             table_name: "TestTable",
             key: {
@@ -430,6 +433,19 @@ module Record
         end
       end
 
+      describe "save after delete scenarios" do
+        it 'sets destroyed to false after saving a destroyed record' do
+          klass.configure_client(client: stub_client)
+          item = klass.new
+          item.id = 3
+          item.date = "2015-12-17"
+          expect(item.delete!).to be(true)
+          expect(item.destroyed?).to be(true)
+          item.save
+          expect(item.destroyed?).to be(false)
+        end
+      end
+
       describe 'nil persistence scenarios' do
         it 'does not persist attributes that are not defined' do
           klass.configure_client(client: stub_client)