ANN: Sequel 2.11.0 Released


J

Jeremy Evans

Sequel is a lightweight database access toolkit for Ruby.

* Sequel provides thread safety, connection pooling and a concise DSL
for constructing database queries and table schemas.
* Sequel also includes a lightweight but 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, master/slave
configurations, and database sharding.
* Sequel makes it easy to deal with multiple records without having
to break your teeth on SQL.
* Sequel currently has adapters for ADO, DataObjects, DB2, DBI,
Firebird, Informix, JDBC, MySQL, ODBC, OpenBase, Oracle, PostgreSQL
and SQLite3.

Sequel 2.11.0 has been released and should be available on the gem
mirrors. The 2.11.0 release adds numerous improvements:

Optimizations
-------------

* Model.[] was optimized to use static SQL in cases where doing so
should result in the same output. This should result in a 30-40%
performance increase. Since this can be the most significant or
only method call in a web application action, this has potential
to significantly enhance the performance of web application code.

In order for this optimization to have an effect, you need to
make sure that you are calling set_dataset with a Symbol and
not a Dataset object:

# Optimized:
class Foo < Sequel::Model; end
class Foo < Sequel::Model:)foos); end
class Foo < Sequel::Model
set_dataset :foos
end

# Not Optimized, but otherwise equivalent:
class Foo < Sequel::Model(Model.db[:foos]); end
class Foo < Sequel::Model
set_dataset db[:foos]
end

* Dataset#literal was refactored for performance reasons to make
overriding it in subclasses unnecessary. The changes made result
in a 20-25% performance increase. Sequel can spend about 10% of
it's time in Dataset#literal, so this may be only a 2% overall
performance improvement.

New Features
------------

* Association datasets now know about the model objects that created
them, as well as the related association reflection. This makes
association extensions much more powerful. For example, you can
now create generic association extensions such as:

module FindOrCreate
def find_or_create(vals)
first(vals) || association_reflection.associated_class. \
create(vals.merge(association_reflection[:key]=> \
model_object.id))
end
end

The above will work for any standard one_to_many association:

Artist.one_to_many :albums, :extend=>FindOrCreate
# Create an album named Foo related to this artist,
# unless such an album already exists
Artist.first.albums_dataset.find_or_create:)name=>'Foo')

Before, the only way to do the above was to use a closure inside
the :dataset option proc, which couldn't be done generically
for multiple associations.

* A :conditions association option was added, which allows simple
filters to be set up without defining :graph_conditions and
an association block:

# 2.10.0
one_to_many:)japanese_verses, :class=>:Verse, \
:graph_conditions=>{:languageid=>3})do |ds|
ds.filter:)languageid=>3)
end
# 2.11.0
one_to_many:)japanese_verses, :class=>:Verse, \
:conditions=>{:languageid=>3})

* A :clone association option was added, which allows you to clone
an existing association. This is most useful when you are dealing
with a legacy schema and had to define the same options redundantly
for each type of association. You can now do:

many_to_many :deputies, :class=>:Employee, \
:join_table=>:employeecurrentaudits, :left_key=>:currentauditid, \
:right_key=>:employeeid, :eek:rder=>[:firstname, :lastname] do |ds|
ds.filter:)active).filter:)capacity=>1)
end
many_to_many :project_managers, :clone=>:deputies do |ds|
ds.filter:)active).filter:)capacity=>2)
end
many_to_many :team_leaders, :clone=>:deputies do |ds|
ds.filter:)active).filter:)capacity=>3)
end

All of the above would use the same :class, :join_table, :left_key,
:right_key, and :eek:rder options. If you don't provide an
association block, but you are cloning an association that has one,
the cloned association's block is used. You can use the
:block=>nil option to not use a block even if the cloned
association has a block.

* Dataset#select, #select_more, #order, #order_more, and #get all
take a block that yields a Sequel::SQL::VirtualRow instance,
similar to the behavior of filter. This allows for the easier
use of SQL functions on Ruby 1.9:

# 2.10.0
dataset.select:)prettify.sql_function:)name))
# 2.11.0
dataset.select{|o| o.prettify:)name)}

* String#lit can now accept arguments and return an SQL literal
string. This allows you to do things that were previously hard
or at least unnecessarily verbose. For example, you can now
easily use the SQL standard SUBSTRING function:

column = :user
pattern = params[:pattern]
dataset.select{|o| o.substring('? from ?'.lit(column, pattern))}

* A validates_inclusion_of validation method was added to Model. You
can provide a Range or an Array in the :in option to specify the
allowed values:

validates_inclusion_of :value, :in=>1..5
validates_inclusion_of :weekday, :in=>%w'Monday Tuesday ...'

* Dataset#with_sql was added, which returns a copy of the dataset
with static SQL. This is useful if you want to keep the same
row_proc/graph/transform/etc., but want to use your own custom
SQL.

Other Improvements
------------------

* You can now use Sequel's database independent types when casting:

dataset.select:)number.cast(String))

Among other things, the default cast types for cast_string and
cast_numeric now work in the MySQL adapter.

* Model#set_associated_object was added. The many_to_one association
setter method calls it. This allows you to easily override the
association setters for all many_to_one associations of a class
by modifying a single method.

* Typecasting invalid date strings now raises a
Sequel::Error::InvalidValue instead of an argument error, which
means that you can use raise_on_typecast_failure = false and not
have an error raised when an invalid date format is used.

* String#to_sequel_blob was added and should now be used instead
of String#to_blob. sqlite3-ruby defines String#to_blob
differently, which could cause problems.

* Blob columns are now fully supported in the SQLite adapter, with
the hex escape syntax being used for input, and returning columns
of type Sequel::SQL::Blob on output.

* The SQLite adapter drop_column support is now significantly more
robust.

* The SQLite adapter now supports rename_column.

* The MySQL adapter now supports stored procedures with multiple
arguments.

* The MySQL adapter can now not use a compressed connection to the
server via the :compress=>false option.

* The MySQL adapter now sets a default timeout of 30 days to the
database connection, you can change it via the :timeout option,
which accepts a number of seconds.

* The MySQL adapter now sets SQL_AUTO_IS_NULL to false by default,
you can use the :auto_is_null=>true option to not do this.

* The MySQL adapter now sets the encoding option on the database
connection itself, so it works across reconnects.

* Sequel itself no longer uses String#lit or Symbol#* internally, so
it shouldn't break if another library defines them.

* The default index name is now generated correctly if a non-String
or Symbol column is used.

* Some ruby -w warnings have been fixed.

* INSERTs are now sent to the master database instead of the slave
database(s) if using a master/slave database configuration and
PostgreSQL 8.2+ or Firebird.

* DateTime literalization has been fixed in the Firebird adapter.

* Date literalization has been fixed in the H2 JDBC subadapter.

* Release notes for versions from 1.0 to the present are now included
in the Sequel repository and the RDoc documentation, see
http://sequel.rubyforge.org/rdoc/files/doc/release_notes/

Backwards Compatibilty
----------------------

* The optimization of Model.[] may break if you modify the model's
dataset behind its back. Always use Model.set_dataset if you
want to change a Model's dataset.

* Sequel::Dataset::UnsupportedExceptIntersect and
Sequel::Dataset::UnsupportedExceptIntersectAll will now only be
defined if you are using an adapter that requires them.

* The private Model#cache_delete_unless_new method has been removed.

* Sequel::SQL::IrregularFunction was removed, as it was a bad hack
that is not used by Sequel anymore. Unless you were instantiating
it directly or using a plugin/extension that did, this shouldn't
affect you. Using a Sequel::SQL::Function with a
Sequel::SQL::placeholderLiteralString is recommended instead, see
the substring example above.

Thanks,
Jeremy

* {Website}[http://sequel.rubyforge.org]
* {Source code}[http://github.com/jeremyevans/sequel]
* {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]
 
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