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
|
module ActiveRecord
module AttributeMethods
module Read
extend ActiveSupport::Concern
ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date]
included do
cattr_accessor :attribute_types_cached_by_default, :instance_writer => false
self.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
# Undefine id so it can be used as an attribute name
undef_method(:id) if method_defined?(:id)
end
module ClassMethods
# +cache_attributes+ allows you to declare which converted attribute values should
# be cached. Usually caching only pays off for attributes with expensive conversion
# methods, like time related columns (e.g. +created_at+, +updated_at+).
def cache_attributes(*attribute_names)
cached_attributes.merge attribute_names.map { |attr| attr.to_s }
end
# Returns the attributes which are cached. By default time related columns
# with datatype <tt>:datetime, :timestamp, :time, :date</tt> are cached.
def cached_attributes
@cached_attributes ||= columns.select { |c| cacheable_column?(c) }.map { |col| col.name }.to_set
end
# Returns +true+ if the provided attribute is being cached.
def cache_attribute?(attr_name)
cached_attributes.include?(attr_name)
end
protected
def define_method_attribute(attr_name)
if serialized_attributes.include?(attr_name)
define_read_method_for_serialized_attribute(attr_name)
else
define_read_method(attr_name, attr_name, columns_hash[attr_name])
end
end
private
def cacheable_column?(column)
serialized_attributes.include?(column.name) || attribute_types_cached_by_default.include?(column.type)
end
# Define read method for serialized attribute.
def define_read_method_for_serialized_attribute(attr_name)
access_code = "@attributes_cache['#{attr_name}'] ||= @attributes['#{attr_name}']"
generated_attribute_methods.module_eval("def _#{attr_name}; #{access_code}; end; alias #{attr_name} _#{attr_name}", __FILE__, __LINE__)
end
# Define an attribute reader method. Cope with nil column.
# method_name is the same as attr_name except when a non-standard primary key is used,
# we still define #id as an accessor for the key
def define_read_method(method_name, attr_name, column)
cast_code = column.type_cast_code('v')
access_code = "(v=@attributes['#{attr_name}']) && #{cast_code}"
unless attr_name.to_s == self.primary_key.to_s
access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless @attributes.has_key?('#{attr_name}'); ")
end
if cache_attribute?(attr_name)
access_code = "@attributes_cache['#{attr_name}'] ||= (#{access_code})"
end
# Where possible, generate the method by evalling a string, as this will result in
# faster accesses because it avoids the block eval and then string eval incurred
# by the second branch.
#
# The second, slower, branch is necessary to support instances where the database
# returns columns with extra stuff in (like 'my_column(omg)').
if method_name =~ ActiveModel::AttributeMethods::NAME_COMPILABLE_REGEXP
generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__
def _#{method_name}
#{access_code}
end
alias #{method_name} _#{method_name}
STR
else
generated_attribute_methods.module_eval do
define_method("_#{method_name}") { eval(access_code) }
alias_method(method_name, "_#{method_name}")
end
end
end
end
# Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
# "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
def read_attribute(attr_name)
method = "_#{attr_name}"
if respond_to? method
send method if @attributes.has_key?(attr_name.to_s)
else
_read_attribute attr_name
end
end
def _read_attribute(attr_name)
attr_name = attr_name.to_s
attr_name = self.class.primary_key if attr_name == 'id'
value = @attributes[attr_name]
unless value.nil?
if column = column_for_attribute(attr_name)
if unserializable_attribute?(attr_name, column)
unserialize_attribute(attr_name)
else
column.type_cast(value)
end
else
value
end
end
end
# Returns true if the attribute is of a text column and marked for serialization.
def unserializable_attribute?(attr_name, column)
column.text? && self.class.serialized_attributes.include?(attr_name)
end
# Returns the unserialized object of the attribute.
def unserialize_attribute(attr_name)
coder = self.class.serialized_attributes[attr_name]
unserialized_object = coder.load(@attributes[attr_name])
@attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object
end
private
def attribute(attribute_name)
read_attribute(attribute_name)
end
end
end
end
|
