Module: TemporalTables::RelationExtensions

Defined in:
lib/temporal_tables/relation_extensions.rb

Overview

Stores the time from the “at” field into each of the resulting objects so that it can be carried forward in subsequent queries.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



7
8
9
10
11
 
# File 'lib/temporal_tables/relation_extensions.rb', line 7

def self.included(base)
  base.class_eval do
    ActiveRecord::Relation::SINGLE_VALUE_METHODS << :at
  end
end

Instance Method Details

#at(*args) ⇒ Object 



21
22
23
 
# File 'lib/temporal_tables/relation_extensions.rb', line 21

def at(*args)
  spawn.at!(*args)
end

#at!(value) ⇒ Object 



25
26
27
28
 
# File 'lib/temporal_tables/relation_extensions.rb', line 25

def at!(value)
  self.at_value = value
  where!(klass.build_temporal_constraint(value))
end

#at_value ⇒ Object 



13
14
15
 
# File 'lib/temporal_tables/relation_extensions.rb', line 13

def at_value
  @values.fetch(:at, nil) || Thread.current[:at_time]
end

#at_value=(value) ⇒ Object 



17
18
19
 
# File 'lib/temporal_tables/relation_extensions.rb', line 17

def at_value=(value)
  @values[:at] = value
end

#default_value_for(name) ⇒ Object

Only needed for Rails 5.1.x



71
72
73
74
75
76
77
 
# File 'lib/temporal_tables/relation_extensions.rb', line 71

def default_value_for(name)
  if name == :at
    nil
  else
    super(name)
  end
end

#exec_queries ⇒ Object 



49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
 
# File 'lib/temporal_tables/relation_extensions.rb', line 49

def exec_queries
  # Note that record preloading, like when you specify
  #  MyClass.includes(:associations)
  # happens within this exec_queries call.  That's why we needed to
  # store the at_time in the thread above.
  records = threadify_at { super }

  if historical?
    # Store the at value on each record returned
    records.each do |r|
      r.at_value = at_value
    end
  end
  @records = records
  records
end

#historical? ⇒ Boolean

Returns:

  • (Boolean) 


66
67
68
 
# File 'lib/temporal_tables/relation_extensions.rb', line 66

def historical?
  table_name =~ /_h$/i && at_value
end

#limited_ids_for(*args) ⇒ Object 



45
46
47
 
# File 'lib/temporal_tables/relation_extensions.rb', line 45

def limited_ids_for(*args)
  threadify_at { super(*args) }
end

#threadify_at ⇒ Object 



34
35
36
37
38
39
40
41
42
43
 
# File 'lib/temporal_tables/relation_extensions.rb', line 34

def threadify_at
  if at_value && !Thread.current[:at_time]
    Thread.current[:at_time] = at_value
    result = yield
    Thread.current[:at_time] = nil
  else
    result = yield
  end
  result
end

#to_sql(*args) ⇒ Object 



30
31
32
 
# File 'lib/temporal_tables/relation_extensions.rb', line 30

def to_sql(*args)
  threadify_at { super(*args) }
end