Raise error on unknown primary key.

If we don't have a primary key when we ask for it, it's better to fail
fast. Fixes GH #2307.

12 files changed, 54 insertions, 18 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index a404a5edd7..36d7f4ad11 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -14,6 +14,8 @@ module ActiveRecord
         # primary_key_prefix_type setting, though.
         def primary_key
           @primary_key ||= reset_primary_key
+          raise ActiveRecord::UnknownPrimaryKey.new(self) unless @primary_key
+          @primary_key
         end
 
         # Returns a quoted version of the primary key name, used to construct SQL statements.
@@ -29,6 +31,11 @@ module ActiveRecord
           key
         end
 
+        def primary_key? #:nodoc:
+          @primary_key ||= reset_primary_key
+          !@primary_key.nil?
+        end
+
         def get_primary_key(base_name) #:nodoc:
           return 'id' unless base_name && !base_name.blank?
 
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
index 4174e4da09..8566ecad14 100644
--- a/activerecord/lib/active_record/attribute_methods/read.rb
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -40,7 +40,7 @@ module ActiveRecord
               define_read_method(attr_name, attr_name, columns_hash[attr_name])
             end
 
-            if attr_name == primary_key && attr_name != "id"
+            if primary_key? && attr_name == primary_key && attr_name != "id"
               define_read_method('id', attr_name, columns_hash[attr_name])
             end
           end
@@ -63,7 +63,7 @@ module ActiveRecord
             cast_code = column.type_cast_code('v')
             access_code = "(v=@attributes['#{attr_name}']) && #{cast_code}"
 
-            unless attr_name.to_s == self.primary_key.to_s
+            unless primary_key? && attr_name.to_s == primary_key.to_s
               access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless @attributes.has_key?('#{attr_name}'); ")
             end
 
@@ -107,7 +107,7 @@ module ActiveRecord
 
       def _read_attribute(attr_name)
         attr_name = attr_name.to_s
-        attr_name = self.class.primary_key if attr_name == 'id'
+        attr_name = self.class.primary_key? && self.class.primary_key if attr_name == 'id'
         value = @attributes[attr_name]
         unless value.nil?
           if column = column_for_attribute(attr_name)
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index e9cdb130db..4db6d71ba6 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -18,7 +18,7 @@ module ActiveRecord
               end
             end
 
-            if attr_name == primary_key && attr_name != "id"
+            if primary_key? && attr_name == primary_key && attr_name != "id"
               generated_attribute_methods.module_eval("alias :id= :'#{primary_key}='")
             end
           end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 78159d13d4..137b4c6534 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -708,7 +708,7 @@ module ActiveRecord #:nodoc:
       # Returns an array of column objects for the table associated with this class.
       def columns
         if defined?(@primary_key)
-          connection_pool.primary_keys[table_name] ||= primary_key
+          connection_pool.primary_keys[table_name] ||= @primary_key
         end
 
         connection_pool.columns[table_name]
@@ -953,7 +953,7 @@ module ActiveRecord #:nodoc:
       # objects of different types from the same table.
       def instantiate(record)
         sti_class = find_sti_class(record[inheritance_column])
-        record_id = sti_class.primary_key && record[sti_class.primary_key]
+        record_id = sti_class.primary_key? && record[sti_class.primary_key]
 
         if ActiveRecord::IdentityMap.enabled? && record_id
           if (column = sti_class.columns_hash[sti_class.primary_key]) && column.number?
@@ -1941,8 +1941,9 @@ MSG
 
       # The primary key and inheritance column can never be set by mass-assignment for security reasons.
       def self.attributes_protected_by_default
-        default = [ primary_key, inheritance_column ]
-        default << 'id' unless primary_key.eql? 'id'
+        default = [ inheritance_column ]
+        default << primary_key if primary_key?
+        default << 'id' unless primary_key? && primary_key == 'id'
         default
       end
 
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index ad7d8cd63c..8262b60f6e 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -169,4 +169,18 @@ module ActiveRecord
       @errors = errors
     end
   end
+
+  # Raised when a model attempts to fetch its primary key from the database, but the table
+  # has no primary key declared.
+  class UnknownPrimaryKey < ActiveRecordError
+    attr_reader :model
+
+    def initialize(model)
+      @model = model
+    end
+
+    def message
+      "Unknown primary key for table #{model.table_name} in model #{model}."
+    end
+  end
 end
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 6f1ec7f9b3..97af15c9e8 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -622,7 +622,7 @@ module ActiveRecord
 
     private
       def primary_key_name
-        @primary_key_name ||= model_class && model_class.primary_key
+        @primary_key_name ||= model_class && model_class.primary_key? && model_class.primary_key
       end
 
       def has_primary_key_column?
diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index 5e65e46a7d..b5dadb929d 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -314,7 +314,7 @@ module ActiveRecord
 
       new_id = self.class.unscoped.insert attributes_values
 
-      self.id ||= new_id if self.class.primary_key
+      self.id ||= new_id if self.class.primary_key?
 
       IdentityMap.add(self) if IdentityMap.enabled?
       @new_record = false
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index ecefaa633c..bf61d79a2c 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -13,7 +13,7 @@ module ActiveRecord
 
     # These are explicitly delegated to improve performance (avoids method_missing)
     delegate :to_xml, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to => :to_a
-    delegate :table_name, :quoted_table_name, :primary_key, :quoted_primary_key, :connection, :column_hash,:to => :klass
+    delegate :table_name, :quoted_table_name, :primary_key, :primary_key?, :quoted_primary_key, :connection, :column_hash,:to => :klass
 
     attr_reader :table, :klass, :loaded
     attr_accessor :extensions, :default_scoped
@@ -36,7 +36,7 @@ module ActiveRecord
     def insert(values)
       primary_key_value = nil
 
-      if primary_key && Hash === values
+      if primary_key? && Hash === values
         primary_key_value = values[values.keys.find { |k|
           k.name == primary_key
         }]
@@ -70,7 +70,7 @@ module ActiveRecord
       conn.insert(
         im,
         'SQL',
-        primary_key,
+        primary_key? && primary_key,
         primary_key_value,
         nil,
         binds)
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index ae97a3f3ca..d4870dd3f2 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -303,7 +303,7 @@ module ActiveRecord
     # Save the new record state and id of a record so it can be restored later if a transaction fails.
     def remember_transaction_record_state #:nodoc
       @_start_transaction_state ||= {}
-      @_start_transaction_state[:id] = id if has_attribute?(self.class.primary_key)
+      @_start_transaction_state[:id] = id if self.class.primary_key?
       unless @_start_transaction_state.include?(:new_record)
         @_start_transaction_state[:new_record] = @new_record
       end
diff --git a/activerecord/test/cases/attribute_methods/read_test.rb b/activerecord/test/cases/attribute_methods/read_test.rb
index e03ed33591..814476ce73 100644
--- a/activerecord/test/cases/attribute_methods/read_test.rb
+++ b/activerecord/test/cases/attribute_methods/read_test.rb
@@ -24,6 +24,10 @@ module ActiveRecord
           def self.primary_key
           end
 
+          def self.primary_key?
+            false
+          end
+
           def self.columns
             column_names.map { FakeColumn.new(name) }
           end
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 12c1cfb30e..77fd1d2fad 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -97,10 +97,6 @@ class BasicsTest < ActiveRecord::TestCase
     assert pk.primary, 'nick should be primary key'
   end
 
-  def test_primary_key_with_no_id
-    assert_nil Edge.primary_key
-  end
-
   unless current_adapter?(:PostgreSQLAdapter,:OracleAdapter,:SQLServerAdapter)
     def test_limit_with_comma
       assert_nothing_raised do
diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb
index 489c7d8310..58badd6266 100644
--- a/activerecord/test/cases/primary_keys_test.rb
+++ b/activerecord/test/cases/primary_keys_test.rb
@@ -5,6 +5,7 @@ require 'models/subscriber'
 require 'models/movie'
 require 'models/keyboard'
 require 'models/mixed_case_monkey'
+require 'models/edge'
 
 class PrimaryKeysTest < ActiveRecord::TestCase
   fixtures :topics, :subscribers, :movies, :mixed_case_monkeys
@@ -161,4 +162,17 @@ class PrimaryKeysTest < ActiveRecord::TestCase
 
     assert_equal 'foo', model.primary_key
   end
+
+  def test_no_primary_key_raises
+    assert_raises(ActiveRecord::UnknownPrimaryKey) do
+      Edge.primary_key
+    end
+
+    begin
+      Edge.primary_key
+    rescue ActiveRecord::UnknownPrimaryKey => e
+      assert e.message.include?('edges')
+      assert e.message.include?('Edge')
+    end
+  end
 end