Merge pull request #12 from magoosh/persistence-methods

New persistence methods

README.md

@@ -57,20 +57,19 @@ end
 Attribute methods are inferred from the associated SQLite table definition.
 
 ```ruby
-message = Message.new(subject: "Welcome!", body: "If you have any questions...")
-# => #<Message: @id=nil @subject="Welcome!" @body="If you have any..." ...>
-message.satisfaction
-# => 0.0
+message = Message.new(subject: "Welcome!")
+# => #<Message: @id=nil @subject="Welcome!" @body=nil, @created_at=nil ...>
 ```
 
-Manage persistence with `save!`, `delete!`, and `persisted?`
+Manage persistence with `create`, `save`, `destroy`, and `persisted?`
 
 ```ruby
-message = Message.new(subject: "Welcome!", body: "If you have any questions...")
-message.save!
-message.id
-# => 1
-message.delete!
+message = Message.create(subject: "Welcome!")
+message.body = "If you have any questions, just ask us :)"
+message.save
+#    SQL: UPDATE messages SET subject = ?, body = ?, ... WHERE id = ?
+# Params: ["Welcome!", "If you have any questions, just ask :)", ..., 1]
+message.destroy
 message.persisted?
 # => false
 ```
@@ -177,7 +176,7 @@ class Message < MotionRecord::Base
   serialize :read_at, :time
 end
 
-Message.create!(subject: "Hello!", read_at: Time.now)
+Message.create(subject: "Hello!", read_at: Time.now)
 #    SQL: INSERT INTO messages (subject, body, read_at, ...) VALUES (?, ?, ?...)
 # Params: ["Hello!", nil, 1420099200, ...]
 Message.first.read_at
@@ -200,11 +199,10 @@ class Survey < MotionRecord::Base
   serialize :response, :json
 end
 
-survey = Survey.new(response: {nps: 10, what_can_we_improve: "Nothing :)"})
-survey.save!
+survey = Survey.create(response: {nps: 10, what_can_we_improve: "Nothing :)"})
 #    SQL: INSERT INTO surveys (response) VALUES (?)
 # Params: ['{"nps":10, "what_can_we_improve":"Nothing :)"}']
-Survey.first
+survey
 # => #<Survey: @id=1 @response={"nps"=>10, "what_can_we_improve"=>"Nothing :)"}>
 ```
 
@@ -216,12 +214,10 @@ class User < MotionRecord::Base
   serialize :birthday, :date
 end
 
-drake = User.new(birthday: Time.new(1986, 10, 24))
-drake.save!
+drake = User.create(birthday: Time.new(1986, 10, 24))
 #    SQL: INSERT INTO users (birthday) VALUES (?)
 # Params: ["1986-10-24"]
-User.first.birthday
-# => 1986-10-24 00:00:00 UTC
+# => #<User: @id=1, @birthday=1986-10-24 00:00:00 UTC>
 ```
 
 #### Custom Serializers

lib/motion_record/persistence.rb

@@ -3,16 +3,12 @@ module Persistence
 
     TIMESTAMP_COLUMNS = [:created_at, :updated_at]
 
-    def save!
+    def save
       persist!
     end
 
-    def delete!
-      if persisted?
-        self.class.where(primary_key_condition).delete_all
-      else
-        raise "Can't delete unpersisted records"
-      end
+    def destroy
+      delete!
     end
 
     def persisted?
@@ -41,11 +37,24 @@ def persist!
         self.class.where(primary_key_condition).update_all(table_params)
       else
         connection.insert self.class.table_name, table_params
+        if self.class.primary_key
+          # HACK: This assumes that primary keys are monotonically increasing
+          newest_primary_key = self.class.maximum(self.class.primary_key)
+          self.self.instance_variable_set "@#{self.class.primary_key}", newest_primary_key
+        end
       end
 
       self.mark_persisted!
     end
 
+    def delete!
+      if persisted?
+        self.class.where(primary_key_condition).delete_all
+      else
+        raise "Can't delete unpersisted records"
+      end
+    end
+
     # Update persistence auto-timestamp attributes
     def apply_persistence_timestamps
       self.updated_at   = Time.now if self.class.attribute_names.include?(:updated_at)
@@ -57,8 +66,15 @@ def primary_key_condition
     end
 
     module ClassMethods
-      def create!(attributes={})
-        self.new(attributes).save!
+      # Create a new record
+      #
+      # attributes - a Hash of attribute values
+      #
+      # Returns the created record
+      def create(attributes={})
+        record = self.new(attributes)
+        record.save
+        record
       end
 
       # Sybmol name of the primary key column

lib/motion_record/schema/migration.rb

@@ -13,6 +13,10 @@ def table_exists?
           connection.table_exists?(table_name)
         end
 
+        def primary_key
+          nil
+        end
+
         def create_table
           table = Schema::TableDefinition.new(table_name, id: false)
           table.integer :version, :null => false

lib/motion_record/schema/migrator.rb

@@ -15,7 +15,7 @@ def run
         pending_migrations.each do |migration|
           migration.execute
           @migrated_versions << migration.version
-          Schema::Migration.create!(version: migration.version)
+          Schema::Migration.create(version: migration.version)
         end 
       end