/usr/lib/ruby/vendor_ruby/active_record/validations/uniqueness.rb is in ruby-activerecord-3.2 3.2.16-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 | require 'active_support/core_ext/array/wrap'
module ActiveRecord
module Validations
class UniquenessValidator < ActiveModel::EachValidator
def initialize(options)
super(options.reverse_merge(:case_sensitive => true))
end
# Unfortunately, we have to tie Uniqueness validators to a class.
def setup(klass)
@klass = klass
end
def validate_each(record, attribute, value)
finder_class = find_finder_class_for(record)
table = finder_class.arel_table
coder = record.class.serialized_attributes[attribute.to_s]
if value && coder
value = coder.dump value
end
relation = build_relation(finder_class, table, attribute, value)
relation = relation.and(table[finder_class.primary_key.to_sym].not_eq(record.send(:id))) if record.persisted?
Array.wrap(options[:scope]).each do |scope_item|
scope_value = record.read_attribute(scope_item)
relation = relation.and(table[scope_item].eq(scope_value))
end
if finder_class.unscoped.where(relation).exists?
record.errors.add(attribute, :taken, options.except(:case_sensitive, :scope).merge(:value => value))
end
end
protected
# The check for an existing value should be run from a class that
# isn't abstract. This means working down from the current class
# (self), to the first non-abstract class. Since classes don't know
# their subclasses, we have to build the hierarchy between self and
# the record's class.
def find_finder_class_for(record) #:nodoc:
class_hierarchy = [record.class]
while class_hierarchy.first != @klass
class_hierarchy.insert(0, class_hierarchy.first.superclass)
end
class_hierarchy.detect { |klass| !klass.abstract_class? }
end
def build_relation(klass, table, attribute, value) #:nodoc:
column = klass.columns_hash[attribute.to_s]
value = column.limit ? value.to_s.mb_chars[0, column.limit] : value.to_s if value && column.text?
if !options[:case_sensitive] && value && column.text?
# will use SQL LOWER function before comparison, unless it detects a case insensitive collation
relation = klass.connection.case_insensitive_comparison(table, attribute, column, value)
else
value = klass.connection.case_sensitive_modifier(value) if value
relation = table[attribute].eq(value)
end
relation
end
end
module ClassMethods
# Validates whether the value of the specified attributes are unique across the system.
# Useful for making sure that only one user
# can be named "davidhh".
#
# class Person < ActiveRecord::Base
# validates_uniqueness_of :user_name
# end
#
# It can also validate whether the value of the specified attributes are unique based on a scope parameter:
#
# class Person < ActiveRecord::Base
# validates_uniqueness_of :user_name, :scope => :account_id
# end
#
# Or even multiple scope parameters. For example, making sure that a teacher can only be on the schedule once
# per semester for a particular class.
#
# class TeacherSchedule < ActiveRecord::Base
# validates_uniqueness_of :teacher_id, :scope => [:semester_id, :class_id]
# end
#
# When the record is created, a check is performed to make sure that no record exists in the database
# with the given value for the specified attribute (that maps to a column). When the record is updated,
# the same check is made but disregarding the record itself.
#
# Configuration options:
# * <tt>:message</tt> - Specifies a custom error message (default is: "has already been taken").
# * <tt>:scope</tt> - One or more columns by which to limit the scope of the uniqueness constraint.
# * <tt>:case_sensitive</tt> - Looks for an exact match. Ignored by non-text columns (+true+ by default).
# * <tt>:allow_nil</tt> - If set to true, skips this validation if the attribute is +nil+ (default is +false+).
# * <tt>:allow_blank</tt> - If set to true, skips this validation if the attribute is blank (default is +false+).
# * <tt>:if</tt> - Specifies a method, proc or string to call to determine if the validation should
# occur (e.g. <tt>:if => :allow_validation</tt>, or <tt>:if => Proc.new { |user| user.signup_step > 2 }</tt>).
# The method, proc or string should return or evaluate to a true or false value.
# * <tt>:unless</tt> - Specifies a method, proc or string to call to determine if the validation should
# not occur (e.g. <tt>:unless => :skip_validation</tt>, or
# <tt>:unless => Proc.new { |user| user.signup_step <= 2 }</tt>). The method, proc or string should
# return or evaluate to a true or false value.
#
# === Concurrency and integrity
#
# Using this validation method in conjunction with ActiveRecord::Base#save
# does not guarantee the absence of duplicate record insertions, because
# uniqueness checks on the application level are inherently prone to race
# conditions. For example, suppose that two users try to post a Comment at
# the same time, and a Comment's title must be unique. At the database-level,
# the actions performed by these users could be interleaved in the following manner:
#
# User 1 | User 2
# ------------------------------------+--------------------------------------
# # User 1 checks whether there's |
# # already a comment with the title |
# # 'My Post'. This is not the case. |
# SELECT * FROM comments |
# WHERE title = 'My Post' |
# |
# | # User 2 does the same thing and also
# | # infers that his title is unique.
# | SELECT * FROM comments
# | WHERE title = 'My Post'
# |
# # User 1 inserts his comment. |
# INSERT INTO comments |
# (title, content) VALUES |
# ('My Post', 'hi!') |
# |
# | # User 2 does the same thing.
# | INSERT INTO comments
# | (title, content) VALUES
# | ('My Post', 'hello!')
# |
# | # ^^^^^^
# | # Boom! We now have a duplicate
# | # title!
#
# This could even happen if you use transactions with the 'serializable'
# isolation level. The best way to work around this problem is to add a unique
# index to the database table using
# ActiveRecord::ConnectionAdapters::SchemaStatements#add_index. In the
# rare case that a race condition occurs, the database will guarantee
# the field's uniqueness.
#
# When the database catches such a duplicate insertion,
# ActiveRecord::Base#save will raise an ActiveRecord::StatementInvalid
# exception. You can either choose to let this error propagate (which
# will result in the default Rails exception page being shown), or you
# can catch it and restart the transaction (e.g. by telling the user
# that the title already exists, and asking him to re-enter the title).
# This technique is also known as optimistic concurrency control:
# http://en.wikipedia.org/wiki/Optimistic_concurrency_control
#
# The bundled ActiveRecord::ConnectionAdapters distinguish unique index
# constraint errors from other types of database errors by throwing an
# ActiveRecord::RecordNotUnique exception.
# For other adapters you will have to parse the (database-specific) exception
# message to detect such a case.
# The following bundled adapters throw the ActiveRecord::RecordNotUnique exception:
# * ActiveRecord::ConnectionAdapters::MysqlAdapter
# * ActiveRecord::ConnectionAdapters::Mysql2Adapter
# * ActiveRecord::ConnectionAdapters::SQLiteAdapter
# * ActiveRecord::ConnectionAdapters::SQLite3Adapter
# * ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
#
def validates_uniqueness_of(*attr_names)
validates_with UniquenessValidator, _merge_attributes(attr_names)
end
end
end
end
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