may configure to not allow direct assignment for persisted AASM models #53

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 4.0.0 (not yet released)
 
+ * may configure to not allow direct assignment for persisted AASM models (see [issue #53](https://github.com/aasm/aasm/issues/53))
  * **DSL change**: callbacks don't require `to_state` parameter anymore, but still support it
    (closing issues
    [#11](https://github.com/aasm/aasm/issues/11),

README.md

@@ -278,6 +278,34 @@ class Job < ActiveRecord::Base
 end
 ```
 
+If you want to make sure that the _AASM_ column for storing the state is not directly assigned,
+configure _AASM_ to not allow direct assignment, like this:
+
+```ruby
+class Job < ActiveRecord::Base
+  include AASM
+
+  aasm :no_direct_assignment => true do
+    state :sleeping, :initial => true
+    state :running
+
+    event :run do
+      transitions :from => :sleeping, :to => :running
+    end
+  end
+
+end
+```
+
+resulting in this:
+
+```ruby
+job = Job.create
+job.aasm_state # => 'sleeping'
+job.aasm_state = :running # => raises AASM::NoDirectAssignmentError
+job.aasm_state # => 'sleeping'
+```
+
 ### Sequel
 
 AASM also supports [Sequel](http://sequel.jeremyevans.net/) besides _ActiveRecord_ and _Mongoid_.

lib/aasm/base.rb

@@ -4,7 +4,7 @@ module AASM
     def initialize(clazz, options={}, &block)
       @clazz = clazz
       @state_machine = AASM::StateMachine[@clazz]
-      @state_machine.config.column = options[:column].to_sym if options[:column]
+      @state_machine.config.column ||= (options[:column] || :aasm_state).to_sym
       @options = options
 
       # let's cry if the transition is invalid
@@ -13,11 +13,21 @@ module AASM
       # create named scopes for each state
       configure :create_scopes, true
 
-      # don't store any new state if the model is invalid
+      # don't store any new state if the model is invalid (in ActiveRecord)
       configure :skip_validation_on_save, false
 
-      # use requires_new for nested transactions
+      # use requires_new for nested transactions (in ActiveRecord)
       configure :requires_new_transaction, true
+
+      # set to true to forbid direct assignment of aasm_state column (in ActiveRecord)
+      configure :no_direct_assignment, false
+
+
+      if @state_machine.config.no_direct_assignment
+        @clazz.send(:define_method, "#{@state_machine.config.column}=") do |state_name|
+          raise AASM::NoDirectAssignmentError.new('direct assignment of AASM column has been disabled (see AASM configuration for this class)')
+        end
+      end
     end
 
     def initial_state(new_initial_state=nil)

lib/aasm/errors.rb

@@ -1,4 +1,5 @@
 module AASM
   class InvalidTransition < RuntimeError; end
   class UndefinedState < RuntimeError; end
+  class NoDirectAssignmentError < RuntimeError; end
 end

spec/database.rb

@@ -1,5 +1,5 @@
 ActiveRecord::Migration.suppress_messages do
-  %w{gates readers writers transients simples simple_new_dsls no_scopes thieves localizer_test_models persisted_states provided_and_persisted_states}.each do |table_name|
+  %w{gates readers writers transients simples simple_new_dsls no_scopes no_direct_assignments thieves localizer_test_models persisted_states provided_and_persisted_states}.each do |table_name|
     ActiveRecord::Migration.create_table table_name, :force => true do |t|
       t.string "aasm_state"
     end

spec/models/persistence.rb

@@ -48,7 +48,22 @@ end
 class NoScope < ActiveRecord::Base
   include AASM
   aasm :create_scopes => false do
-    state :ignored_scope
+    state :pending, :initial => true
+    state :running
+    event :run do
+      transitions :from => :pending, :to => :running
+    end
+  end
+end
+
+class NoDirectAssignment < ActiveRecord::Base
+  include AASM
+  aasm :no_direct_assignment => true do
+    state :pending, :initial => true
+    state :running
+    event :run do
+      transitions :from => :pending, :to => :running
+    end
   end
 end
 

spec/unit/persistence/active_record_persistence_spec.rb

@@ -93,10 +93,28 @@ describe "named scopes with the new DSL" do
   end
 
   it "does not create scopes if requested" do
-    expect(NoScope).not_to respond_to(:ignored_scope)
+    expect(NoScope).not_to respond_to(:pending)
   end
 
-end
+end # scopes
+
+describe "direct assignment" do
+  it "is allowed by default" do
+    obj = NoScope.create
+    expect(obj.aasm_state.to_sym).to eql :pending
+
+    obj.aasm_state = :running
+    expect(obj.aasm_state.to_sym).to eql :running
+  end
+
+  it "is forbidden if configured" do
+    obj = NoDirectAssignment.create
+    expect(obj.aasm_state.to_sym).to eql :pending
+
+    expect {obj.aasm_state = :running}.to raise_error(AASM::NoDirectAssignmentError)
+    expect(obj.aasm_state.to_sym).to eql :pending
+  end
+end # direct assignment
 
 describe 'initial states' do