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# frozen-string-literal: true
module Sequel
module Plugins
# The prepared_statements_safe plugin modifies the model to reduce the number of
# prepared statements that can be created, by setting as many columns as possible
# before creating, and by changing +save_changes+ to save all columns instead of
# just the changed ones.
#
# This plugin depends on the +prepared_statements+ plugin.
#
# Usage:
#
# # Make all model subclasses more safe when using prepared statements (called before loading subclasses)
# Sequel::Model.plugin :prepared_statements_safe
#
# # Make the Album class more safe when using prepared statements
# Album.plugin :prepared_statements_safe
module PreparedStatementsSafe
# Depend on the prepared_statements plugin
def self.apply(model)
model.plugin(:prepared_statements)
end
# Set the column defaults to use when creating on the model.
def self.configure(model)
model.send(:set_prepared_statements_column_defaults)
end
module ClassMethods
# A hash with column symbol keys and default values. Instance
# values are merged into this hash before creating to reduce the
# number of free columns (columns that may or may not be present
# in the INSERT statement), as the number of prepared statements
# that can be created is 2^N (where N is the number of free columns).
attr_reader :prepared_statements_column_defaults
Plugins.inherited_instance_variables(self, :@prepared_statements_column_defaults=>:dup)
Plugins.after_set_dataset(self, :set_prepared_statements_column_defaults)
# Freeze the prepared statements column defaults when freezing the model class.
def freeze
@prepared_statements_column_defaults.freeze if @prepared_statements_column_defaults
super
end
private
# Set the column defaults based on the database schema. All columns
# are set to a default value unless they are a primary key column or
# they don't have a parseable default.
def set_prepared_statements_column_defaults
if db_schema
h = {}
db_schema.each do |k, v|
default = v[:ruby_default]
h[k] = default if (default || !v[:default]) && !v[:primary_key] && !default.is_a?(Sequel::SQL::Expression)
end
@prepared_statements_column_defaults = h
end
end
end
module InstanceMethods
# Merge the current values into the default values to reduce the number
# of free columns.
def before_create
@values = model.prepared_statements_column_defaults.merge(@values)
super
end
# Always do a full save of all columns to reduce the number of prepared
# statements that can be used.
def save_changes(opts=OPTS)
save(opts) || false if modified?
end
end
end
end
end
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