Rename error that occurs when writing on a read

I originally named this `StatementInvalid` because that's what we do in
GitHub, but `@tenderlove` pointed out that this means apps can't test
for or explitly rescue this error. `StatementInvalid` is pretty broad so
I've renamed this to `ReadOnlyError`.

4 files changed, 7 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
index 43e2f628dc..56f777f3be 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
@@ -29,7 +29,7 @@ module ActiveRecord
         # Executes the SQL statement in the context of this connection.
         def execute(sql, name = nil)
           if preventing_writes? && write_query?(sql)
-            raise ActiveRecord::StatementInvalid, "Write query attempted while in readonly mode: #{sql}"
+            raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
           end
 
           # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
index 2d5b592639..d93c1f449e 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
@@ -80,7 +80,7 @@ module ActiveRecord
         # need it specifically, you may want consider the <tt>exec_query</tt> wrapper.
         def execute(sql, name = nil)
           if preventing_writes? && write_query?(sql)
-            raise ActiveRecord::StatementInvalid, "Write query attempted while in readonly mode: #{sql}"
+            raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
           end
 
           materialize_transactions
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 615aa0d83e..dcad230335 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -265,7 +265,7 @@ module ActiveRecord
 
       def execute(sql, name = nil) #:nodoc:
         if preventing_writes? && write_query?(sql)
-          raise ActiveRecord::StatementInvalid, "Write query attempted while in readonly mode: #{sql}"
+          raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
         end
 
         materialize_transactions
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index 7e6d4c1d46..0858af3874 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -49,6 +49,10 @@ module ActiveRecord
   class ConnectionNotEstablished < ActiveRecordError
   end
 
+  # Raised when a write to the database is attempted on a read only connection.
+  class ReadOnlyError < ActiveRecordError
+  end
+
   # Raised when Active Record cannot find a record by given id or set of ids.
   class RecordNotFound < ActiveRecordError
     attr_reader :model, :primary_key, :id