5 files changed, 90 insertions, 15 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index b0686e9e53..a4508c9086 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,8 @@
 *SVN*
 
+* Constraints are cloned so they can't be inadvertently modified while they're
+in effect.  Added :readonly finder constraint.  Calling an association collection's class method (Part.foobar via item.parts.foobar) constrains :readonly => false since the collection's :joins constraint would otherwise force it to true.  [Jeremy Kemper <rails@bitsweat.net>]
+
 * Added :offset and :limit to the kinds of options that Base.constrain can use #2466 [duane.johnson@gmail.com]
 
 * Fixed handling of nil number columns on Oracle and cleaned up tests for Oracle in general #2555 [schoenm@earthlink.net]
diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index 164d11b2d1..cbfbdf1541 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -128,7 +128,7 @@ module ActiveRecord
           if @target.respond_to?(method) or (not @association_class.respond_to?(method) and Class.respond_to?(method))
             super
           else
-            @association_class.constrain(:conditions => @finder_sql, :joins => @join_sql) { @association_class.send(method, *args, &block) }
+            @association_class.constrain(:conditions => @finder_sql, :joins => @join_sql, :readonly => false) { @association_class.send(method, *args, &block) }
           end
         end
               
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index febb35dd5b..fa7ed9482a 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -384,9 +384,14 @@ module ActiveRecord #:nodoc:
       def find(*args)
         options = extract_options_from_args!(args)
 
-        # :joins implies :readonly => true if unset.
-        if options[:joins] and !options.has_key?(:readonly)
-          options[:readonly] = true
+        # Inherit :readonly from scope_constraints if set.  Otherwise,
+        # if :joins is not blank then :readonly defaults to true.
+        unless options.has_key?(:readonly)
+          if scope_constraints.has_key?(:readonly)
+            options[:readonly] = scope_constraints[:readonly]
+          elsif !options[:joins].blank?
+            options[:readonly] = true
+          end
         end
 
         case args.first
@@ -815,13 +820,15 @@ module ActiveRecord #:nodoc:
       #   Article.constrain(:conditions => "blog_id = 1") do
       #     Article.find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
       #   end
-      def constrain(options = {}, &block)
-        begin
-          self.scope_constraints = options
-          block.call if block_given?
-        ensure 
-          self.scope_constraints = nil
+      def constrain(options = {})
+        options = options.dup
+        if !options[:joins].blank? and !options.has_key?(:readonly)
+          options[:readonly] = true
         end
+        self.scope_constraints = options
+        yield if block_given?
+      ensure 
+        self.scope_constraints = nil
       end
 
       # Overwrite the default class equality method to provide support for association proxies.
diff --git a/activerecord/test/conditions_scoping_test.rb b/activerecord/test/conditions_scoping_test.rb
index b945593b57..a997ee9e85 100644
--- a/activerecord/test/conditions_scoping_test.rb
+++ b/activerecord/test/conditions_scoping_test.rb
@@ -41,6 +41,15 @@ class ConditionsScopingTest < Test::Unit::TestCase
       assert_equal 1, Developer.count("name LIKE 'fixture_1%'")
     end        
   end
+
+  def test_immutable_constraint
+    options = { :conditions => "name = 'David'" }
+    Developer.constrain(options) do
+      assert_equal %w(David), Developer.find(:all).map { |d| d.name }
+      options[:conditions] = "name != 'David'"
+      assert_equal %w(David), Developer.find(:all).map { |d| d.name }
+    end
+  end
 end
 
 class HasManyScopingTest< Test::Unit::TestCase
diff --git a/activerecord/test/readonly_test.rb b/activerecord/test/readonly_test.rb
index 458cd6886f..d621432596 100755
--- a/activerecord/test/readonly_test.rb
+++ b/activerecord/test/readonly_test.rb
@@ -1,12 +1,19 @@
 require 'abstract_unit'
+require 'fixtures/post'
+require 'fixtures/comment'
 require 'fixtures/developer'
 require 'fixtures/project'
 
+# Dummy class methods to test implicit association constraints.
+def Comment.foo() find :first end
+def Project.foo() find :first end
+
+
 class ReadOnlyTest < Test::Unit::TestCase
-  fixtures :developers, :projects, :developers_projects
+  fixtures :posts, :comments, :developers, :projects, :developers_projects
 
   def test_cant_save_readonly_record
-    dev = Developer.find(:first)
+    dev = Developer.find(1)
     assert !dev.readonly?
 
     dev.readonly!
@@ -21,21 +28,70 @@ class ReadOnlyTest < Test::Unit::TestCase
     assert_raise(ActiveRecord::ReadOnlyRecord) { dev.save! }
   end
 
+
   def test_find_with_readonly_option
     Developer.find(:all).each { |d| assert !d.readonly? }
     Developer.find(:all, :readonly => false).each { |d| assert !d.readonly? }
     Developer.find(:all, :readonly => true).each { |d| assert d.readonly? }
   end
 
+
   def test_find_with_joins_option_implies_readonly
-    Developer.find(:all, :joins => '').each { |d| assert d.readonly? }
-    Developer.find(:all, :joins => '', :readonly => false).each { |d| assert !d.readonly? }
+    # Blank joins don't count.
+    Developer.find(:all, :joins => '  ').each { |d| assert !d.readonly? }
+    Developer.find(:all, :joins => '  ', :readonly => false).each { |d| assert !d.readonly? }
+
+    # Others do.
+    Developer.find(:all, :joins => ', projects').each { |d| assert d.readonly? }
+    Developer.find(:all, :joins => ', projects', :readonly => false).each { |d| assert !d.readonly? }
   end
 
+
   def test_habtm_find_readonly
-    dev = Developer.find(:first)
+    dev = Developer.find(1)
+    assert !dev.projects.empty?
     dev.projects.each { |p| assert !p.readonly? }
     dev.projects.find(:all) { |p| assert !p.readonly? }
     dev.projects.find(:all, :readonly => true) { |p| assert p.readonly? }
   end
+
+  def test_has_many_find_readonly
+    post = Post.find(1)
+    assert !post.comments.empty?
+    post.comments.each { |r| assert !r.readonly? }
+    post.comments.find(:all) { |r| assert !r.readonly? }
+    post.comments.find(:all, :readonly => true) { |r| assert r.readonly? }
+  end
+
+
+  def test_readonly_constraint
+    Post.constrain(:conditions => '1=1') do 
+      assert !Post.find(1).readonly?
+      assert Post.find(1, :readonly => true).readonly?
+      assert !Post.find(1, :readonly => false).readonly?
+    end
+
+    Post.constrain(:joins => '   ') do 
+      assert !Post.find(1).readonly?
+      assert Post.find(1, :readonly => true).readonly?
+      assert !Post.find(1, :readonly => false).readonly?
+    end
+
+    Post.constrain(:joins => ', developers') do 
+      assert Post.find(1).readonly?
+      assert Post.find(1, :readonly => true).readonly?
+      assert !Post.find(1, :readonly => false).readonly?
+    end
+
+    Post.constrain(:readonly => true) do
+      assert Post.find(1).readonly?
+      assert Post.find(1, :readonly => true).readonly?
+      assert !Post.find(1, :readonly => false).readonly?
+    end
+  end
+
+  def test_association_collection_method_missing_constraint_not_readonly
+    assert !Developer.find(1).projects.foo.readonly?
+    assert !Post.find(1).comments.foo.readonly?
+  end
 end