Fix KeyValueStoreAgent

app/models/agents/key_value_store_agent.rb

@@ -40,6 +40,7 @@ class KeyValueStoreAgent < Agent
 
       - Keys are always stringified as mandated by the JSON format.
       - Values are stringified by default.  Use the `as_object` filter to store non-string values.
+      - If the key is evaluated to an empty string, the event is ignored.
       - If the value is evaluated to either `null` or empty (`""`, `[]`, `{}`) the key gets deleted.
       - In the `value` template, the existing value (if any) can be accessed via the variable `_value_`.
       - In the `key` and `value` templates, the whole event payload can be accessed via the variable `_event_`.
@@ -99,13 +100,19 @@ def receive(incoming_events)
             interpolation_context['_event_'] = event.payload
 
             key = interpolate_options(options)['key'].to_s
+            next if key.empty?
 
             storage = memory
             interpolation_context['_value_'] = storage.delete(key)
 
-            storage[key] = interpolate_options(options)['value']
+            value = interpolate_options(options)['value']
 
-            storage.shift while storage.size > max_keys
+            if value.nil? || value.try(:empty?)
+              storage.delete(key)
+            else
+              storage[key] = value
+              storage.shift while storage.size > max_keys
+            end
 
             update!(memory: storage)
           end

db/migrate/20230622140301_delete_empty_keys_and_values_from_key_value_store_agents.rb

@@ -0,0 +1,8 @@
+class DeleteEmptyKeysAndValuesFromKeyValueStoreAgents < ActiveRecord::Migration[6.1]
+  def up
+    Agents::KeyValueStoreAgent.find_each do |agent|
+      agent.memory.delete_if { |key, value| key.empty? || value.nil? || value.try(:empty?) }
+      agent.save!
+    end
+  end
+end

spec/models/agents/key_value_store_agent_spec.rb

@@ -21,7 +21,7 @@
   end
 
   def create_event(payload)
-    source_agent.events.create!(payload: payload)
+    source_agent.events.create!(payload:)
   end
 
   let(:events) do
@@ -112,6 +112,47 @@ def create_event(payload)
           "4" => { id: 4, name: "quux" },
         }
       )
+
+      expect {
+        agent.receive([create_event({ name: "empty key" })])
+      }.not_to(change { agent.reload.memory })
+    end
+
+    describe "empty value" do
+      let(:value_template) { "{{ name | as_object }}" }
+
+      it "deletes the key" do
+        agent.receive(events[0..2])
+
+        expect(agent.reload.memory).to match(
+          {
+            "1" => "foo",
+            "2" => "bar",
+            "3" => "baz",
+          }
+        )
+
+        agent.receive([create_event({ id: 1, name: "" })])
+
+        expect(agent.reload.memory).to match(
+          {
+            "2" => "bar",
+            "3" => "baz",
+          }
+        )
+
+        agent.receive([create_event({ id: 2, name: [] })])
+
+        expect(agent.reload.memory).to match(
+          {
+            "3" => "baz",
+          }
+        )
+
+        agent.receive([create_event({ id: 3, name: {} })])
+
+        expect(agent.reload.memory).to eq({})
+      end
     end
 
     describe "using _value_" do