3.39.0.txt

doc/release_notes/3.39.0.txt
Last Update: 2012-09-01 08:15:50 -0700

New Features

  • A constraint_validations extension and plugin have been added, which allow you to define validations when creating tables, which are enforced by database constraints, and have those validations be automatically discovered and used by your Sequel::Model classes.

    The extension is designed to be used in your migrations/schema modification code:

    DB.extension(:constraint_validations)
    DB.create_constraint_validations_table
    DB.create_table(:foos) do
      primary_key :id
      String :name
    
      validate do
        min_length 5, :name
      end
    end

    This creates a database CHECK constraint that ensures that the minimum length for the column is 5 characters. It also adds metadata about the validation to the sequel_constraint_validations table.

    To have the model class automatically create validations, just include the plugin in the model:

    class Foo < Sequel::Model
      plugin :constraint_validations
    end

    Note that MySQL does not enforce CHECK constraints (it parses but ignores them), so using the extension on MySQL does not actually enforce constraints at the database level, though it still does support the automatic model validations if the plugin is used.

  • Dataset#count now takes an argument or a virtual row block, allowing you to do:

    DB[:table].count(:column_name)
    DB[:table].count{function_name(column1, column2)}

    When count is given an argument, instead of returning the total number of rows, it returns the number of rows where the argument has a non-NULL value.

  • Database#copy_into has been added to the postgres adapter when the pg driver is being used, and can be used for very fast inserts into tables if you already have the input preformatted in PostgreSQL text or CSV format.

  • set_table_not_null has been added to the alter table generator, for a nicer API:

    alter_table(:t){set_column_not_null :col}
    # instead of
    alter_table(:t){set_column_allow_null :col, false}

    Additionally, set_column_allow_null now defaults the second argument to true for a nicer API:

    alter_table(:t){set_column_allow_null :col}
    # instead of
    alter_table(:t){set_column_allow_null :col, true}
  • Database#supports_regexp? has been added for checking if the database supports Regexp in filters. Currently, only MySQL and PostgreSQL support Regexps.

    Attempting to use a Regexp on a database that doesn't support it now raises an error when attempting to generate the SQL, instead of sending invalid SQL to the database.

  • Sequel.char_length has been added for a cross platform char_length function (emulated when char_length is not supported natively by the database).

  • Sequel.trim has been added for a cross platform trim function (emulated when trim is not supported natively by the database).

  • ValidationFailed and HookFailed exceptions now have a model method that returns the model instance related to the exception. This makes it possible to use Model.create inside a begin/rescue block and get access to the underlying instance if there is a validation or before/around hook error.

  • The subclasses plugin now accepts a block, which is called with each model class created. This is useful if you want to apply changes to classes created in the future instead of just existing classes.

  • The validates_unique validation in the validation_helpers plugin now accepts a :where option for a custom uniqueness filter. Among other things this makes it easy to implement a case insensitive uniqueness validation on a case sensitive column.

  • The threaded connection pools now support a :connection_handling=>:disconnect option, which makes them disconnect connections after use instead of returning them to the pool. This makes it possible to completely control connection lifetime using Database#synchronize.

  • The pg_row_op extension now has support for PGRowOp#*, for referencing the members of the composite type as separate columns.

  • MySQL's set type and default value are now recognized.

  • bin/sequel now accepts a -c argument for running an arbitrary code string instead of using an IRB prompt.

Other Improvements

  • Sequel now parses current date/timestamp column defaults when parsing the schema for a table. The values will be returned as Sequel::CURRENT_DATE for date columns and Sequel::CURRENT_TIMESTAMP for timestamp columns.

    The schema_dumper extension will work with these defaults, so if you dump the schema for a table with a column that uses a current timestamp default, the dumped schema will include the default.

    The defaults setter plugin also works with these changes, so that when new model objects are instantiated, they get the current Date/Time/DateTime values set.

  • On MySQL and PostgreSQL, Sequel will now by default attempt to combine multiple alter_table operations into a single query where it believes it can do so correctly. This can potentially improve performance ~N times, where N is the number of alter table operations.

    This can change the SQL used for old migrations (though it shouldn't change the result), and is a potentially risky change. This may be disabled by default in future versions if it causes problems.

  • The defaults_setter plugin now correctly sets false default values.

  • The schema_dumper plugin now preserves fractional seconds in timestamp column defaults when dumping.

  • Time->DateTime and DateTime->Time typecasts now retain fractional seconds on ruby 1.8.

  • Array arguments passed to most PGArrayOp methods are now automatically wrapped in a PGArray. If you want to use this support, you need to make sure to load both the pg_array and pg_array_op extensions.

  • Sequel now does a better job of finding the sequence for a given table on PostgreSQL, handling more corner cases. A small side effect of this is sometimes sequence names will be quoted.

  • Some potential thread-safety issues when using Sequel with PostgreSQL on a non-GVL ruby implementation have been fixed.

  • Sequel now correctly caches the server version query on MySQL.

  • Sets of alter_table operations on MySQL and Microsoft SQL Server that require parsing the current database schema, where later alter_table operations depend on earlier ones, should now work correctly.

  • You can now drop check constraints on tables on SQLite, though doing so drops all check constraints on the table, not only the specific check constraint given.

  • The identity_map plugin no longer breaks if used with a model without a primary key.

  • Sequel::SQL::NegativeBooleanConstant now inherits from Constant instead of BooleanConstant. This means that

    Sequel::NULL == Sequel::NOTNULL

    is now false instead of true.

  • You can now override the convert_tinyint_to_bool settings on a per-Dataset basis in the mysql and mysql2 adapters, though the overriding is different depending on the adapter. Check the commit log for details.

  • timestamp(N) types are now recognized as datetime, which should fix certain cases on Oracle.

  • Dataset#insert now handles a single model instance argument as a single value if the model uses the pg_row plugin.

  • When joining a model dataset using a model class as the table argument, a subselect is used unless the model is a simple select from the underlying table.

  • The specs now cleanup after themselves, dropping the tables that they create for testing.

Backwards Compatibility

  • The defaults_setter plugin's behavior changed due to the current date/timestamp support. Previously, it would not set a value for the column, since the default wasn't recognized. Therefore, the database would use the default value on insert, which would be the database's current timestamp.

    Now, the value is set to the current Date/Time/DateTime on model object instantiation, so the database wouldn't use the column default. Instead of the database's current timestamp on insert, the column value will be the application's current timestamp on model instantiation.

    Users who don't want this behavior can remove the default values in the model:

    Model.default_values.delete(:column_name)
  • Plain (non-model) datasets no longer allow insert to accept a single model instance argument. Also, they no longer call values on a single argument if the object responds to it.

  • Plain (non-model) datasets no longer accept model classes as tables in the join/graph methods. Also, they no longer call table_name on the argument if the object responds to it.

  • The schema_dumper extension now requires the eval_inspect extension, which changes inspect output for Sequel::SQL::Expression objects.

  • Custom adapters that override Database#alter_table_sql_list now need to make sure it returns an already flattened array.

  • The identity_map_key method in the identity_map plugin now returns nil instead of a random string if the given pk is nil.