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
181
182
|
module ActiveRecord
module Associations
class JoinDependency # :nodoc:
class JoinAssociation < JoinPart # :nodoc:
# The reflection of the association represented
attr_reader :reflection
# The JoinDependency object which this JoinAssociation exists within. This is mainly
# relevant for generating aliases which do not conflict with other joins which are
# part of the query.
attr_reader :join_dependency
# A JoinBase instance representing the active record we are joining onto.
# (So in Author.has_many :posts, the Author would be that base record.)
attr_reader :parent
# What type of join will be generated, either Arel::InnerJoin (default) or Arel::OuterJoin
attr_accessor :join_type
# These implement abstract methods from the superclass
attr_reader :aliased_prefix
attr_reader :tables
delegate :options, :through_reflection, :source_reflection, :chain, :to => :reflection
delegate :table, :table_name, :to => :parent, :prefix => :parent
delegate :alias_tracker, :to => :join_dependency
def initialize(reflection, join_dependency, parent = nil)
reflection.check_validity!
if reflection.options[:polymorphic]
raise EagerLoadPolymorphicError.new(reflection)
end
super(reflection.klass)
@reflection = reflection
@join_dependency = join_dependency
@parent = parent
@join_type = Arel::InnerJoin
@aliased_prefix = "t#{ join_dependency.join_parts.size }"
setup_tables
end
def ==(other)
other.class == self.class &&
other.reflection == reflection &&
other.parent == parent
end
def find_parent_in(other_join_dependency)
other_join_dependency.join_parts.detect do |join_part|
parent == join_part
end
end
def join_to(relation)
tables = @tables.dup
foreign_table = parent_table
# The chain starts with the target table, but we want to end with it here (makes
# more sense in this context), so we reverse
chain.reverse.each_with_index do |reflection, i|
table = tables.shift
case reflection.source_macro
when :belongs_to
key = reflection.association_primary_key
foreign_key = reflection.foreign_key
when :has_and_belongs_to_many
# Join the join table first...
relation = relation.from(join(
table,
table[reflection.foreign_key].
eq(foreign_table[reflection.active_record_primary_key])
))
foreign_table, table = table, tables.shift
key = reflection.association_primary_key
foreign_key = reflection.association_foreign_key
else
key = reflection.foreign_key
foreign_key = reflection.active_record_primary_key
end
conditions = self.conditions[i].dup
conditions << table[key].eq(foreign_table[foreign_key])
if reflection.klass.finder_needs_type_condition?
conditions << reflection.klass.send(:type_condition, table)
end
relation = relation.from(join(table, *conditions))
# The current table in this iteration becomes the foreign table in the next
foreign_table = table
end
relation
end
def join_relation(joining_relation)
self.join_type = Arel::OuterJoin
joining_relation.joins(self)
end
def table
tables.last
end
def aliased_table_name
table.table_alias || table.name
end
def conditions
@conditions ||= reflection.conditions.reverse
end
private
def table_alias_for(reflection, join = false)
name = alias_tracker.pluralize(reflection.name)
name << "_#{parent_table_name}"
name << "_join" if join
name
end
# Generate aliases and Arel::Table instances for each of the tables which we will
# later generate joins for. We must do this in advance in order to correctly allocate
# the proper alias.
def setup_tables
@tables = []
chain.each do |reflection|
@tables << alias_tracker.aliased_table_for(
reflection.table_name,
table_alias_for(reflection, reflection != self.reflection)
)
if reflection.source_macro == :has_and_belongs_to_many
@tables << alias_tracker.aliased_table_for(
(reflection.source_reflection || reflection).options[:join_table],
table_alias_for(reflection, true)
)
end
end
# We construct the tables in the forward order so that the aliases are generated
# correctly, but then reverse the array because that is the order in which we will
# iterate the chain.
@tables.reverse!
end
def join(table, *conditions)
conditions = sanitize_conditions(table, conditions)
table.create_join(table, table.create_on(conditions), join_type)
end
def sanitize_conditions(table, conditions)
conditions = conditions.map do |condition|
condition = active_record.send(:sanitize_sql, interpolate(condition), table.table_alias || table.name)
condition = Arel.sql(condition) unless condition.is_a?(Arel::Node)
condition
end
conditions.length == 1 ? conditions.first : Arel::Nodes::And.new(conditions)
end
def interpolate(conditions)
if conditions.respond_to?(:to_proc)
instance_eval(&conditions)
else
conditions
end
end
end
end
end
end
|
