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 



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# 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 



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

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

#at!(value) ⇒ Object 



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# 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 



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# 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 



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# 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



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# File 'lib/temporal_tables/relation_extensions.rb', line 73

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

#exec_queries ⇒ Object 



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# File 'lib/temporal_tables/relation_extensions.rb', line 51

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) 


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

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

#limited_ids_for(*args) ⇒ Object 



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

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

#threadify_at ⇒ Object 



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# File 'lib/temporal_tables/relation_extensions.rb', line 34

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

#to_sql(*args) ⇒ Object 



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

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