Class: InventoryRefresh::ApplicationRecordIterator

Inherits:
Object
  • Object
show all
Defined in:
lib/inventory_refresh/application_record_iterator.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(inventory_collection: nil) ⇒ ApplicationRecordIterator

An iterator that can fetch batches of the AR objects based on a set of attribute_indexes

Parameters:



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# File 'lib/inventory_refresh/application_record_iterator.rb', line 8

def initialize(inventory_collection: nil)
  @inventory_collection = inventory_collection
end

Instance Attribute Details

#inventory_collection ⇒ Object (readonly)

Returns the value of attribute inventory_collection.



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# File 'lib/inventory_refresh/application_record_iterator.rb', line 3

def inventory_collection
  @inventory_collection
end

Instance Method Details

#find_each(attributes_index: {}) { ... } ⇒ Object

Iterator that mimics find_each of ActiveRecord::Relation using find_in_batches (see #find_in_batches)

Yields:

  • Code processing the batches



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# File 'lib/inventory_refresh/application_record_iterator.rb', line 31

def find_each(attributes_index: {})
  find_in_batches(:attributes_index => attributes_index) do |batch|
    batch.each do |item|
      yield(item)
    end
  end
end

#find_in_batches(batch_size: 1000, attributes_index: {}) { ... } ⇒ Object

Iterator that mimics find_in_batches of ActiveRecord::Relation. This iterator serves for making more optimized query since e.g. having 1500 ids if objects we want to return. Doing relation.where(:id => 1500ids).find_each would always search for all 1500 ids, then return on limit 1000.

With this iterator we build queries using only batch of ids, so find_each will cause relation.where(:id => 1000ids) and relation.where(:id => 500ids)

Parameters:

  • batch_size (Integer) (defaults to: 1000) —

    A batch size we want to fetch from DB

  • attributes_index (Hash{String => Hash}) (defaults to: {}) —

    Indexed hash with data we will be saving

Yields:

  • Code processing the batches



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# File 'lib/inventory_refresh/application_record_iterator.rb', line 22

def find_in_batches(batch_size: 1000, attributes_index: {})
  attributes_index.each_slice(batch_size) do |batch|
    yield(inventory_collection.db_collection_for_comparison_for(batch))
  end
end