1 files changed, 49 insertions, 27 deletions
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index 7f6228131f..fc28ab585f 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -30,17 +30,18 @@ module ActiveRecord
   class SerializationTypeMismatch < ActiveRecordError
   end
 
-  # Raised when adapter not specified on connection (or configuration file <tt>config/database.yml</tt>
-  # misses adapter field).
+  # Raised when adapter not specified on connection (or configuration file
+  # +config/database.yml+ misses adapter field).
   class AdapterNotSpecified < ActiveRecordError
   end
 
-  # Raised when Active Record cannot find database adapter specified in <tt>config/database.yml</tt> or programmatically.
+  # Raised when Active Record cannot find database adapter specified in
+  # +config/database.yml+ or programmatically.
   class AdapterNotFound < ActiveRecordError
   end
 
-  # Raised when connection to the database could not been established (for example when <tt>connection=</tt>
-  # is given a nil object).
+  # Raised when connection to the database could not been established (for
+  # example when +connection=+ is given a nil object).
   class ConnectionNotEstablished < ActiveRecordError
   end
 
@@ -51,10 +52,29 @@ module ActiveRecord
   # Raised by ActiveRecord::Base.save! and ActiveRecord::Base.create! methods when record cannot be
   # saved because record is invalid.
   class RecordNotSaved < ActiveRecordError
+    attr_reader :record
+
+    def initialize(message, record = nil)
+      @record = record
+      super(message)
+    end
   end
 
   # Raised by ActiveRecord::Base.destroy! when a call to destroy would return false.
+  #
+  #   begin
+  #     complex_operation_that_internally_calls_destroy!
+  #   rescue ActiveRecord::RecordNotDestroyed => invalid
+  #     puts invalid.record.errors
+  #   end
+  #
   class RecordNotDestroyed < ActiveRecordError
+    attr_reader :record
+
+    def initialize(record)
+      @record = record
+      super()
+    end
   end
 
   # Superclass for all database execution errors.
@@ -82,35 +102,26 @@ module ActiveRecord
   class InvalidForeignKey < WrappedDatabaseException
   end
 
-  # Raised when number of bind variables in statement given to <tt>:condition</tt> key (for example,
-  # when using +find+ method)
-  # does not match number of expected variables.
+  # Raised when number of bind variables in statement given to +:condition+ key
+  # (for example, when using +find+ method) does not match number of expected
+  # values supplied.
   #
-  # For example, in
+  # For example, when there are two placeholders with only one value supplied:
   #
   #   Location.where("lat = ? AND lng = ?", 53.7362)
-  #
-  # two placeholders are given but only one variable to fill them.
   class PreparedStatementInvalid < ActiveRecordError
   end
 
-  # Raised when a given database does not exist
-  class NoDatabaseError < ActiveRecordError
-    def initialize(message)
-      super extend_message(message)
-    end
-
-    # can be over written to add additional error information.
-    def extend_message(message)
-      message
-    end
+  # Raised when a given database does not exist.
+  class NoDatabaseError < StatementInvalid
   end
 
   # Raised on attempt to save stale record. Record is stale when it's being saved in another query after
   # instantiation, for example, when two users edit the same wiki page and one starts editing and saves
   # the page before the other.
   #
-  # Read more about optimistic locking in ActiveRecord::Locking module RDoc.
+  # Read more about optimistic locking in ActiveRecord::Locking module
+  # documentation.
   class StaleObjectError < ActiveRecordError
     attr_reader :record, :attempted_action
 
@@ -122,8 +133,9 @@ module ActiveRecord
 
   end
 
-  # Raised when association is being configured improperly or
-  # user tries to use offset and limit together with has_many or has_and_belongs_to_many associations.
+  # Raised when association is being configured improperly or user tries to use
+  # offset and limit together with +has_many+ or +has_and_belongs_to_many+
+  # associations.
   class ConfigurationError < ActiveRecordError
   end
 
@@ -161,7 +173,8 @@ module ActiveRecord
   class Rollback < ActiveRecordError
   end
 
-  # Raised when attribute has a name reserved by Active Record (when attribute has name of one of Active Record instance methods).
+  # Raised when attribute has a name reserved by Active Record (when attribute
+  # has name of one of Active Record instance methods).
   class DangerousAttributeError < ActiveRecordError
   end
 
@@ -173,16 +186,17 @@ module ActiveRecord
     def initialize(record, attribute)
       @record = record
       @attribute = attribute.to_s
-      super("unknown attribute: #{attribute}")
+      super("unknown attribute '#{attribute}' for #{@record.class}.")
     end
 
   end
 
   # Raised when an error occurred while doing a mass assignment to an attribute through the
-  # <tt>attributes=</tt> method. The exception has an +attribute+ property that is the name of the
+  # +attributes=+ method. The exception has an +attribute+ property that is the name of the
   # offending attribute.
   class AttributeAssignmentError < ActiveRecordError
     attr_reader :exception, :attribute
+
     def initialize(message, exception, attribute)
       super(message)
       @exception = exception
@@ -195,6 +209,7 @@ module ActiveRecord
   # objects, each corresponding to the error while assigning to an attribute.
   class MultiparameterAssignmentErrors < ActiveRecordError
     attr_reader :errors
+
     def initialize(errors)
       @errors = errors
     end
@@ -225,6 +240,13 @@ module ActiveRecord
   class ImmutableRelation < ActiveRecordError
   end
 
+  # TransactionIsolationError will be raised under the following conditions:
+  #
+  # * The adapter does not support setting the isolation level
+  # * You are joining an existing open transaction
+  # * You are creating a nested (savepoint) transaction
+  #
+  # The mysql, mysql2 and postgresql adapters support setting the transaction isolation level.
   class TransactionIsolationError < ActiveRecordError
   end
 end