From 72193453d4508061e8757d53245b2e219bfe99a3 Mon Sep 17 00:00:00 2001
From: Akinori MUSHA <knu@idaemons.org>
Date: Thu, 22 Jun 2023 23:05:53 +0900
Subject: [PATCH 1/3] KeyValueStoreAgent deletes a key if the value is empty as
 documented

---
 app/models/agents/key_value_store_agent.rb    | 11 ++++--
 .../agents/key_value_store_agent_spec.rb      | 39 ++++++++++++++++++-
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/app/models/agents/key_value_store_agent.rb b/app/models/agents/key_value_store_agent.rb
index 20a99bf7dd..94b1a191e2 100644
--- a/app/models/agents/key_value_store_agent.rb
+++ b/app/models/agents/key_value_store_agent.rb
@@ -103,9 +103,14 @@ def receive(incoming_events)
             storage = memory
             interpolation_context['_value_'] = storage.delete(key)
 
-            storage[key] = interpolate_options(options)['value']
-
-            storage.shift while storage.size > max_keys
+            value = interpolate_options(options)['value']
+
+            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
diff --git a/spec/models/agents/key_value_store_agent_spec.rb b/spec/models/agents/key_value_store_agent_spec.rb
index a6a5de6c04..60f9b3275d 100644
--- a/spec/models/agents/key_value_store_agent_spec.rb
+++ b/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
@@ -114,6 +114,43 @@ def create_event(payload)
       )
     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
       let(:value_template) { "{% if _value_ %}{{ _value_ }}, {% endif %}{{ name }}" }
 

From 5ab6261f99b0bb19d15293f7dbc6a4f9ba830a58 Mon Sep 17 00:00:00 2001
From: Akinori MUSHA <knu@idaemons.org>
Date: Thu, 22 Jun 2023 23:07:13 +0900
Subject: [PATCH 2/3] KeyValueStoreAgent now ignores an empty key

---
 app/models/agents/key_value_store_agent.rb       | 2 ++
 spec/models/agents/key_value_store_agent_spec.rb | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/app/models/agents/key_value_store_agent.rb b/app/models/agents/key_value_store_agent.rb
index 94b1a191e2..324fc56346 100644
--- a/app/models/agents/key_value_store_agent.rb
+++ b/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_`.
@@ -99,6 +100,7 @@ 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)
diff --git a/spec/models/agents/key_value_store_agent_spec.rb b/spec/models/agents/key_value_store_agent_spec.rb
index 60f9b3275d..ccd81b57d6 100644
--- a/spec/models/agents/key_value_store_agent_spec.rb
+++ b/spec/models/agents/key_value_store_agent_spec.rb
@@ -112,6 +112,10 @@ 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

From 7eabed25b4d72e65e3036cdf97c4602f385cac67 Mon Sep 17 00:00:00 2001
From: Akinori MUSHA <knu@idaemons.org>
Date: Thu, 22 Jun 2023 23:07:26 +0900
Subject: [PATCH 3/3] Add a migration to delete empty keys and values from
 KeyValueStoreAgents

---
 ...e_empty_keys_and_values_from_key_value_store_agents.rb | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 db/migrate/20230622140301_delete_empty_keys_and_values_from_key_value_store_agents.rb

diff --git a/db/migrate/20230622140301_delete_empty_keys_and_values_from_key_value_store_agents.rb b/db/migrate/20230622140301_delete_empty_keys_and_values_from_key_value_store_agents.rb
new file mode 100644
index 0000000000..788eb6a97b
--- /dev/null
+++ b/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