From 6899c9fd89b830143c0e7484c3ec79c1fa03c8f6 Mon Sep 17 00:00:00 2001
From: Rowan Seymour <rowanseymour@gmail.com>
Date: Mon, 2 Dec 2024 15:52:15 +0000
Subject: [PATCH] Include previous result value on run_result_changed events

---
 flows/actions/base.go              | 4 ++--
 flows/events/run_result_changed.go | 6 +++++-
 flows/interfaces.go                | 2 +-
 flows/results.go                   | 9 ++++++---
 flows/routers/base.go              | 4 ++--
 flows/runs/run.go                  | 6 +++---
 6 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/flows/actions/base.go b/flows/actions/base.go
index 5a2dee0d2..d2e53bfdd 100644
--- a/flows/actions/base.go
+++ b/flows/actions/base.go
@@ -126,8 +126,8 @@ func (a *baseAction) evaluateMessage(run flows.Run, languages []i18n.Language, a
 // helper to save a run result and log it as an event
 func (a *baseAction) saveResult(run flows.Run, step flows.Step, name, value, category, categoryLocalized string, input string, extra json.RawMessage, logEvent flows.EventCallback) {
 	result := flows.NewResult(name, value, category, categoryLocalized, step.NodeUUID(), input, extra, dates.Now())
-	run.SaveResult(result)
-	logEvent(events.NewRunResultChanged(result))
+	prev := run.SaveResult(result)
+	logEvent(events.NewRunResultChanged(result, prev))
 }
 
 // helper to save a run result based on a webhook call and log it as an event
diff --git a/flows/events/run_result_changed.go b/flows/events/run_result_changed.go
index 3e156be3d..835aca3c0 100644
--- a/flows/events/run_result_changed.go
+++ b/flows/events/run_result_changed.go
@@ -38,10 +38,13 @@ type RunResultChangedEvent struct {
 	CategoryLocalized string          `json:"category_localized,omitempty"`
 	Input             string          `json:"input,omitempty"`
 	Extra             json.RawMessage `json:"extra,omitempty"`
+
+	// not included in JSON - used internally to track changes
+	Previous *flows.Result `json:"-"`
 }
 
 // NewRunResultChanged returns a new save result event for the passed in values
-func NewRunResultChanged(result *flows.Result) *RunResultChangedEvent {
+func NewRunResultChanged(result, prev *flows.Result) *RunResultChangedEvent {
 	return &RunResultChangedEvent{
 		BaseEvent:         NewBaseEvent(TypeRunResultChanged),
 		Name:              result.Name,
@@ -50,5 +53,6 @@ func NewRunResultChanged(result *flows.Result) *RunResultChangedEvent {
 		CategoryLocalized: result.CategoryLocalized,
 		Input:             result.Input,
 		Extra:             result.Extra,
+		Previous:          prev,
 	}
 }
diff --git a/flows/interfaces.go b/flows/interfaces.go
index 827afc19a..35cd695eb 100644
--- a/flows/interfaces.go
+++ b/flows/interfaces.go
@@ -410,7 +410,7 @@ type Run interface {
 	FlowReference() *assets.FlowReference
 
 	Session() Session
-	SaveResult(*Result)
+	SaveResult(*Result) *Result
 	SetStatus(RunStatus)
 	Webhook() *WebhookCall
 	SetWebhook(*WebhookCall)
diff --git a/flows/results.go b/flows/results.go
index b606490c3..47883e23b 100644
--- a/flows/results.go
+++ b/flows/results.go
@@ -100,9 +100,12 @@ func (r Results) Clone() Results {
 	return clone
 }
 
-// Save saves a new result in our map. The key is saved in a snakified format
-func (r Results) Save(result *Result) {
-	r[utils.Snakify(result.Name)] = result
+// Save saves a new result in our map using the snakified name as the key. Returns the old result if it existed.
+func (r Results) Save(result *Result) *Result {
+	key := utils.Snakify(result.Name)
+	old := r[key]
+	r[key] = result
+	return old
 }
 
 // Get returns the result with the given key
diff --git a/flows/routers/base.go b/flows/routers/base.go
index 2553ab72f..361a90592 100644
--- a/flows/routers/base.go
+++ b/flows/routers/base.go
@@ -178,8 +178,8 @@ func (r *baseRouter) routeToCategory(run flows.Run, step flows.Step, categoryUUI
 			extraJSON, _ = jsonx.Marshal(extra)
 		}
 		result := flows.NewResult(r.resultName, match, category.Name(), localizedCategory, step.NodeUUID(), operand, extraJSON, dates.Now())
-		run.SaveResult(result)
-		logEvent(events.NewRunResultChanged(result))
+		prev := run.SaveResult(result)
+		logEvent(events.NewRunResultChanged(result, prev))
 	}
 
 	return category.ExitUUID(), nil
diff --git a/flows/runs/run.go b/flows/runs/run.go
index b5f801f28..54173769a 100644
--- a/flows/runs/run.go
+++ b/flows/runs/run.go
@@ -71,14 +71,14 @@ func (r *run) Contact() *flows.Contact              { return r.session.Contact()
 func (r *run) Events() []flows.Event                { return r.events }
 
 func (r *run) Results() flows.Results { return r.results }
-func (r *run) SaveResult(result *flows.Result) {
+func (r *run) SaveResult(result *flows.Result) *flows.Result {
 	// truncate value if necessary
 	result.Value = stringsx.Truncate(result.Value, r.session.Engine().Options().MaxResultChars)
 
-	r.results.Save(result)
 	r.modifiedOn = dates.Now()
-
 	r.legacyExtra.addResult(result)
+
+	return r.results.Save(result)
 }
 
 func (r *run) Exit(status flows.RunStatus) {