diff --git a/CHANGELOG b/CHANGELOG
index b84c0ae999..39074ce862 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
=== HEAD
+* Add instance_filters plugin, for adding arbitrary filters when updating/destroying the instance (jeremyevans)
+
* No longer create the #{plugin}_opts methods for plugins (jeremyevans)
* Support :auto_vacuum, :foreign_keys, :synchronous, and :temp_store Database options on SQLite, for thread-safe PRAGMA setting (jeremyevans)
diff --git a/lib/sequel/plugins/instance_filters.rb b/lib/sequel/plugins/instance_filters.rb
new file mode 100644
index 0000000000..8a5d4b5f38
--- /dev/null
+++ b/lib/sequel/plugins/instance_filters.rb
@@ -0,0 +1,102 @@
+module Sequel
+ module Plugins
+ # This plugin allows you to add filters on a per object basis that
+ # restrict updating or deleting the object. It's designed for cases
+ # where you would normally have to drop down to the dataset level
+ # to get the necessary control, because you only want to delete or
+ # update the rows in certain cases based on the current status of
+ # the row in the database.
+ #
+ # class Item < Sequel::Model
+ # plugin :instance_filters
+ # end
+ #
+ # # These are two separate objects that represent the same
+ # # database row.
+ # i1 = Item.first(:id=>1, :delete_allowed=>false)
+ # i2 = Item.first(:id=>1, :delete_allowed=>false)
+ #
+ # # Add an instance filter to the object. This filter is in effect
+ # # until the object is successfully updated or deleted.
+ # i1.instance_filter(:delete_allowed=>true)
+ #
+ # # Attempting to delete the object where the filter doesn't
+ # # match any rows raises an error.
+ # i1.delete # raises Sequel::Error
+ #
+ # # The other object that represents the same row has no
+ # # instance filters, and can be updated normally.
+ # i2.update(:delete_allowed=>true)
+ #
+ # # Even though the filter is now still in effect, since the
+ # # database row has been updated to allow deleting,
+ # # delete now works.
+ # i1.delete
+ module InstanceFilters
+ # Exception class raised when updating or deleting an object does
+ # not affect exactly one row.
+ class Error < Sequel::Error
+ end
+
+ module InstanceMethods
+ # Clear the instance filters after successfully destroying the object.
+ def after_destroy
+ super
+ clear_instance_filters
+ end
+
+ # Clear the instance filters after successfully updating the object.
+ def after_update
+ super
+ clear_instance_filters
+ end
+
+ # Add an instance filter to the array of instance filters
+ # Both the arguments given and the block are passed to the
+ # dataset's filter method.
+ def instance_filter(*args, &block)
+ instance_filters << [args, block]
+ end
+
+ private
+
+ # Lazily initialize the instance filter array.
+ def instance_filters
+ @instance_filters ||= []
+ end
+
+ # Apply the instance filters to the given dataset
+ def apply_instance_filters(ds)
+ instance_filters.inject(ds){|ds, i| ds.filter(*i[0], &i[1])}
+ end
+
+ # Clear the instance filters.
+ def clear_instance_filters
+ instance_filters.clear
+ end
+
+ # Apply the instance filters to the dataset returned by super.
+ def _delete_dataset
+ apply_instance_filters(super)
+ end
+
+ # Apply the instance filters to the dataset returned by super.
+ def _update_dataset
+ apply_instance_filters(super)
+ end
+
+ # Raise an Error if calling deleting doesn't
+ # indicate that a single row was deleted.
+ def _delete
+ raise(Error, "No matching object for instance filtered dataset (SQL: #{_delete_dataset.delete_sql})") if super != 1
+ end
+
+ # Raise an Error if updating doesn't indicate that a single
+ # row was updated.
+ def _update(columns)
+ raise(Error, "No matching object for instance filtered dataset (SQL: #{_update_dataset.update_sql(columns)})") if super != 1
+ end
+ end
+ end
+ end
+end
diff --git a/spec/extensions/instance_filters_spec.rb b/spec/extensions/instance_filters_spec.rb
new file mode 100644
index 0000000000..e1c88c20ff
--- /dev/null
+++ b/spec/extensions/instance_filters_spec.rb
@@ -0,0 +1,55 @@
+require File.join(File.dirname(__FILE__), "spec_helper")
+
+describe "instance_filters plugin" do
+ before do
+ @c = Class.new(Sequel::Model(:people)) do
+ end
+ @sql = sql = ''
+ @v = v = [1]
+ @c.dataset.quote_identifiers = false
+ @c.dataset.meta_def(:update) do |opts|
+ sql.replace(update_sql(opts))
+ return v.first
+ end
+ @c.dataset.meta_def(:delete) do
+ sql.replace(delete_sql)
+ return v.first
+ end
+ @c.columns :id, :name, :num
+ @c.plugin :instance_filters
+ @p = @c.load(:id=>1, :name=>'John', :num=>1)
+ end
+
+ specify "should raise an error when updating a stale record" do
+ @p.update(:name=>'Bob')
+ @sql.should == "UPDATE people SET name = 'Bob' WHERE (id = 1)"
+ @p.instance_filter(:name=>'Jim')
+ @v.replace([0])
+ proc{@p.update(:name=>'Joe')}.should raise_error(Sequel::Plugins::InstanceFilters::Error)
+ @sql.should == "UPDATE people SET name = 'Joe' WHERE ((id = 1) AND (name = 'Jim'))"
+ end
+
+ specify "should raise an error when destroying a stale record" do
+ @p.destroy
+ @sql.should == "DELETE FROM people WHERE (id = 1)"
+ @p.instance_filter(:name=>'Jim')
+ @v.replace([0])
+ proc{@p.destroy}.should raise_error(Sequel::Plugins::InstanceFilters::Error)
+ @sql.should == "DELETE FROM people WHERE ((id = 1) AND (name = 'Jim'))"
+ end
+
+ specify "should apply all instance filters" do
+ @p.instance_filter(:name=>'Jim')
+ @p.instance_filter{num > 2}
+ @p.update(:name=>'Bob')
+ @sql.should == "UPDATE people SET name = 'Bob' WHERE ((id = 1) AND (name = 'Jim') AND (num > 2))"
+ end
+
+ specify "should drop instance filters after updating" do
+ @p.instance_filter(:name=>'Joe')
+ @p.update(:name=>'Joe')
+ @sql.should == "UPDATE people SET name = 'Joe' WHERE ((id = 1) AND (name = 'Joe'))"
+ @p.update(:name=>'Bob')
+ @sql.should == "UPDATE people SET name = 'Bob' WHERE (id = 1)"
+ end
+end
diff --git a/spec/integration/plugin_test.rb b/spec/integration/plugin_test.rb
index cabde9f990..f0b9bd2b60 100644
--- a/spec/integration/plugin_test.rb
+++ b/spec/integration/plugin_test.rb
@@ -752,3 +752,63 @@ class ::Node < Sequel::Model(@db)
end
end
end
+
+describe "Instance Filters plugin" do
+ before do
+ @db = INTEGRATION_DB
+ @db.create_table!(:items) do
+ primary_key :id
+ String :name
+ Integer :cost
+ Integer :number
+ end
+ class ::Item < Sequel::Model(@db)
+ plugin :instance_filters
+ end
+ @i = Item.create(:name=>'J', :number=>1, :cost=>2)
+ @i.instance_filter(:number=>1)
+ @i.set(:name=>'K')
+ end
+ after do
+ @db.drop_table(:items)
+ Object.send(:remove_const, :Item)
+ end
+
+ specify "should not raise an error if saving only updates one row" do
+ @i.save
+ @i.refresh.name.should == 'K'
+ end
+
+ specify "should raise error if saving doesn't update a row" do
+ @i.this.update(:number=>2)
+ proc{@i.save}.should raise_error(Sequel::Error)
+ end
+
+ specify "should apply all instance filters" do
+ @i.instance_filter{cost <= 2}
+ @i.this.update(:number=>2)
+ proc{@i.save}.should raise_error(Sequel::Error)
+ @i.this.update(:number=>1, :cost=>3)
+ proc{@i.save}.should raise_error(Sequel::Error)
+ @i.this.update(:cost=>2)
+ @i.save
+ @i.refresh.name.should == 'K'
+ end
+
+ specify "should clear instance filters after successful save" do
+ @i.save
+ @i.this.update(:number=>2)
+ @i.update(:name=>'L')
+ @i.refresh.name.should == 'L'
+ end
+
+ specify "should not raise an error if deleting only deletes one row" do
+ @i.destroy
+ proc{@i.refresh}.should raise_error(Sequel::Error, 'Record not found')
+ end
+
+ specify "should raise error if destroying doesn't delete a row" do
+ @i.this.update(:number=>2)
+ proc{@i.destroy}.should raise_error(Sequel::Error)
+ end
+end
diff --git a/www/pages/plugins b/www/pages/plugins
index 8995fa8d71..53e19bb71a 100644
--- a/www/pages/plugins
+++ b/www/pages/plugins
@@ -15,7 +15,8 @@
force_encoding: Forces the all model column string values to a given encoding.
hook_class_methods: Adds backwards compatiblity for the legacy class-level hook methods (e.g. before_save :do_something).
identity_map: Allows you to create temporary identity maps which ensure a 1-1 correspondence of model objects to database rows.
-instance_hooks: Allow you to add hooks to specific model instances.
+instance_filters: Allows you to add per instance filters that are used when updating or destroying the instance.
+instance_hooks: Allows you to add hooks to specific model instances.
lazy_attributes: Allows you to set some attributes that should not be loaded by default, but only loaded when an object requests them.
many_through_many: Allow you to create an association to multiple objects through multiple join tables.
nested_attributes: Allow you to modified associated objects directly through a model object, similar to ActiveRecord's Nested Attributes.