ANN: Sequel 3.18.0 Released

[Jeremy Evans]

Sequel is a lightweight database access toolkit for Ruby.

* Sequel provides thread safety, connection pooling and a concise
DSL for constructing SQL queries and table schemas.
* Sequel includes a comprehensive ORM layer for mapping records to
Ruby objects and handling associated records.
* Sequel supports advanced database features such as prepared
statements, bound variables, stored procedures, savepoints,
two-phase commit, transaction isolation, master/slave
configurations, and database sharding.
* Sequel currently has adapters for ADO, Amalgalite, DataObjects,
DB2, DBI, Firebird, Informix, JDBC, MySQL, Mysql2, ODBC, OpenBase,
Oracle, PostgreSQL, SQLite3, and Swift.

Sequel 3.18.0 has been released and should be available on the gem
mirrors.

= New Features

* Reversible migration support has been added:

Sequel.migration do
change do
create_tableartists) do
primary_key :id
String :name, :null=>false
end
end
end

The change block acts the same way as an up block, except that
it automatically creates a down block that reverses the changes.
So the above is equivalent to:

Sequel.migration do
up do
create_tableartists) do
primary_key :id
String :name, :null=>false
end
end
down do
drop_table :artists
end
end

The following methods are supported in a change block:

* create_table
* add_column
* add_index
* rename_column
* rename_table
* alter_table (supporting the following methods):
* add_column
* add_constraint
* add_foreign_key (with a symbol, not an array)
* add_primary_key (with a symbol, not an array)
* add_index
* add_full_text_index
* add_spatial_index
* rename_column

Use of an other method in a change block will result in the
creation of a down block that raises an exception.

* A to_dot extension has been added that adds a Dataset#to_dot
method, which returns a string that can be used as input to
the graphviz dot program in order to create visualizations
of the dataset's abstract syntax tree. Examples:

* http://sequel.heroku.com/images/to_dot_simple.gif
* http://sequel.heroku.com/images/to_dot_complex.gif
* http://imgpaste.com/i/lxngy.gif

Both the to_dot extension and reversible migrations support
were inspired by Aaron Patterson's recent work on ActiveRecord
and ARel.

* The user can now control how the connection pool handles attempts
to access shards that haven't been configured. The default is
still to assume the :default shard. However, you can specify a
different shard using the :servers_hash option when connecting
to the database:

DB = Sequel.connect(..., :servers_hash=>Hash.newsome_shard))

You can also use this feature to raise an exception if an
unconfigured shard is used:

DB = Sequel.connect(..., :servers_hash=>Hash.new{raise ...})

* The mysql and mysql2 adapters now both support the :read_timeout
and :connect_timeout options. read_timeout is the timeout in
seconds for reading back results of a query, and connect_timeout
is the timeout in seconds before a connection attempt is abandoned.

= Other Improvements

* The json_serializer plugin will now typecast column values for
columns with unrestricted setter methods when parsing JSON into
model objects. It now also calls the getter method when creating
the JSON, instead of directly taking the values from the underlying
hash.

* When parsing the schema for a model with an aliased table name,
the unaliased table name is now used.

* The SQLite adapter has been updated to not rely on the native
type_translation support, since that will be removed in the next
major version of sqlite3-ruby. Sequel now implements it's own
type translation in the sqlite adapter, similarly to how the mysql
and postgres adapters handle type translation.

* On SQLite, when emulating natively unsupported schema methods such
as drop_column, Sequel will now attempt to recreate applicable
indexes on the underlying table.

* A more informative error message is now used when connecting fails
when using the jdbc adapter.

* method_missing is no longer removed from Sequel::BasicObject on
ruby 1.8. This should improve compatibility in some cases with
Rubinius.

= Backwards Compatibility

* On SQLite, Sequel no longer assumes that a plain integer in a
datetime or timestamp field represents a unix epoch time.

* Previously, saving a model object that used the instance_hooks
plugin removed all instance hooks. Now, only the applicable hooks
are removed. So if you save a new object, the update instance
hooks won't be removed. And if you save an existing object, delete
instance hooks won't be removed.

* The private Dataset#identifier_list method has been moved into the
SQLite adapter, since that is the only place it was used.

Thanks,
Jeremy

* {Website}[http://sequel.rubyforge.org]
* {Source code}[http://github.com/jeremyevans/sequel]
* {Blog}[http://sequel.heroku.com]
* {Bug tracking}[http://code.google.com/p/ruby-sequel/issues/list]
* {Google group}[http://groups.google.com/group/sequel-talk]
* {RDoc}[http://sequel.rubyforge.org/rdoc]