Add NULL and NOT_NULL operators

Author: andrykonchin

lib/dynamoid/adapter_plugin/aws_sdk_v3.rb

@@ -22,8 +22,6 @@ class AwsSdkV3
         range_eq:           'EQ'
       }.freeze
 
-      # Don't implement NULL and NOT_NULL because it doesn't make seanse -
-      # we declare schema in models
       FIELD_MAP = {
         eq:           'EQ',
         ne:           'NE',
@@ -35,7 +33,9 @@ class AwsSdkV3
         between:      'BETWEEN',
         in:           'IN',
         contains:     'CONTAINS',
-        not_contains: 'NOT_CONTAINS'
+        not_contains: 'NOT_CONTAINS',
+        null:         'NULL',
+        not_null:     'NOT_NULL',
       }.freeze
       HASH_KEY  = 'HASH'
       RANGE_KEY = 'RANGE'
@@ -619,15 +619,15 @@ def result_item_to_hash(item)
       # https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Condition.html
       # @params [String] operator: value of RANGE_MAP or FIELD_MAP hash, e.g. "EQ", "LT" etc
       # @params [Object] value: scalar value or array/set
-      def attribute_value_list(operator, value)
-        self.class.attribute_value_list(operator, value)
-      end
-
       def self.attribute_value_list(operator, value)
         # For BETWEEN and IN operators we should keep value as is (it should be already an array)
+        # NULL and NOT_NULL require absence of attribute list
         # For all the other operators we wrap the value with array
+        # https://docs.aws.amazon.com/en_us/amazondynamodb/latest/developerguide/LegacyConditionalParameters.Conditions.html
         if %w[BETWEEN IN].include?(operator)
           [value].flatten
+        elsif %w[NULL NOT_NULL].include?(operator)
+          nil
         else
           [value]
         end

lib/dynamoid/adapter_plugin/aws_sdk_v3/scan.rb

@@ -75,6 +75,8 @@ def scan_filter
               comparison_operator: AwsSdkV3::FIELD_MAP[cond.keys[0]],
               attribute_value_list: AwsSdkV3.attribute_value_list(AwsSdkV3::FIELD_MAP[cond.keys[0]], cond.values[0].freeze)
             }
+            # nil means operator doesn't require attribute value list
+            conditions.delete(:attribute_value_list) if conditions[:attribute_value_list].nil?
             result[attr] = condition
             result
           end

lib/dynamoid/criteria/chain.rb

@@ -271,6 +271,13 @@ def field_hash(key)
                  { contains: val }
                when 'not_contains'
                  { not_contains: val }
+               # NULL/NOT_NULL operators don't have parameters
+               # So { null: true } means NULL check and { null: false } means NOT_NULL one
+               # The same logic is used for { not_null: BOOL }
+               when 'null'
+                 val ? { null: nil } : { not_null: nil }
+               when 'not_null'
+                 val ? { not_null: nil } : { null: nil }
                end
 
         { name.to_sym => hash }
@@ -314,10 +321,15 @@ def range_query
         opts.merge(query_opts).merge(consistent_opts)
       end
 
+      # TODO casting should be operator aware
+      # e.g. for NULL operator value should be boolean
+      # and isn't related to an attribute own type
       def type_cast_condition_parameter(key, value)
         return value if %i[array set].include?(source.attributes[key.to_sym][:type])
 
-        if !value.respond_to?(:to_ary)
+        if [true, false].include?(value) # Support argument for null/not_null operators
+          value
+        elsif !value.respond_to?(:to_ary)
           options = source.attributes[key.to_sym]
           value_casted = TypeCasting.cast_field(value, options)
           Dumping.dump_field(value_casted, options)

spec/dynamoid/criteria/chain_spec.rb

@@ -341,6 +341,34 @@ def request_params
       expect(model.where(name: 'a', 'job_title.not_contains': 'Consul').all)
         .to contain_exactly(customer2)
     end
+
+    it 'supports null' do
+      model.create_table
+
+      put_attributes(model.table_name, name: 'a', last_name: 'aa', age: 1)
+      put_attributes(model.table_name, name: 'a', last_name: 'bb', age: 2)
+      put_attributes(model.table_name, name: 'a', last_name: 'cc', )
+
+      documents = model.where(name: 'a', 'age.null': true).to_a
+      expect(documents.map(&:last_name)).to contain_exactly('cc')
+
+      documents = model.where(name: 'a', 'age.null': false).to_a
+      expect(documents.map(&:last_name)).to contain_exactly('aa', 'bb')
+    end
+
+    it 'supports not_null' do
+      model.create_table
+
+      put_attributes(model.table_name, name: 'a', last_name: 'aa', age: 1)
+      put_attributes(model.table_name, name: 'a', last_name: 'bb', age: 2)
+      put_attributes(model.table_name, name: 'a', last_name: 'cc', )
+
+      documents = model.where(name: 'a', 'age.not_null': true).to_a
+      expect(documents.map(&:last_name)).to contain_exactly('aa', 'bb')
+
+      documents = model.where('age.not_null': false).to_a
+      expect(documents.map(&:last_name)).to contain_exactly('cc')
+    end
   end
 
   # http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.ScanFilter.html?shortFooter=true
@@ -490,6 +518,34 @@ def request_params
       expect(model.where('job_title.not_contains': 'Consul').all)
         .to contain_exactly(customer2)
     end
+
+    it 'supports null' do
+      model.create_table
+
+      put_attributes(model.table_name, id: '1', age: 1)
+      put_attributes(model.table_name, id: '2', age: 2)
+      put_attributes(model.table_name, id: '3')
+
+      documents = model.where('age.null': true).to_a
+      expect(documents.map(&:id)).to contain_exactly('3')
+
+      documents = model.where('age.null': false).to_a
+      expect(documents.map(&:id)).to contain_exactly('1', '2')
+    end
+
+    it 'supports not_null' do
+      model.create_table
+
+      put_attributes(model.table_name, id: '1', age: 1)
+      put_attributes(model.table_name, id: '2', age: 2)
+      put_attributes(model.table_name, id: '3')
+
+      documents = model.where('age.not_null':  true).to_a
+      expect(documents.map(&:id)).to contain_exactly('1', '2')
+
+      documents = model.where('age.not_null':  false).to_a
+      expect(documents.map(&:id)).to contain_exactly('3')
+    end
   end
 
   describe 'Lazy loading' do

spec/spec_helper.rb

@@ -47,5 +47,6 @@
   config.include NewClassHelper
   config.include DumpingHelper
   config.include PersistenceHelper
+  config.include ChainHelper
   config.include ActiveSupport::Testing::TimeHelpers
 end

spec/support/chain_helper.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module ChainHelper
+  def put_attributes(table_name, attributes)
+    Dynamoid.adapter.put_item(table_name, attributes)
+  end
+end