Callback for tracing sql queries

callback.go

@@ -13,6 +13,7 @@ var DefaultCallback = &Callback{}
 //   Field `deletes` contains callbacks will be call when deleting object
 //   Field `queries` contains callbacks will be call when querying object with query methods like Find, First, Related, Association...
 //   Field `rowQueries` contains callbacks will be call when querying object with Row, Rows...
+//   Field `trace` contains callbacks will be call after any sql query was executed
 //   Field `processors` contains all callback processors, will be used to generate above callbacks in order
 type Callback struct {
 	creates    []*func(scope *Scope)
@@ -20,6 +21,7 @@ type Callback struct {
 	deletes    []*func(scope *Scope)
 	queries    []*func(scope *Scope)
 	rowQueries []*func(scope *Scope)
+	trace      []*func(scope *Scope)
 	processors []*CallbackProcessor
 }
 
@@ -43,6 +45,7 @@ func (c *Callback) clone() *Callback {
 		queries:    c.queries,
 		rowQueries: c.rowQueries,
 		processors: c.processors,
+		trace:      c.trace,
 	}
 }
 
@@ -79,6 +82,11 @@ func (c *Callback) RowQuery() *CallbackProcessor {
 	return &CallbackProcessor{kind: "row_query", parent: c}
 }
 
+// Trace could be used to register callbacks for tracing sql queries, refer `Create` for usage
+func (c *Callback) Trace() *CallbackProcessor {
+	return &CallbackProcessor{kind: "trace", parent: c}
+}
+
 // After insert a new callback after callback `callbackName`, refer `Callbacks.Create`
 func (cp *CallbackProcessor) After(callbackName string) *CallbackProcessor {
 	cp.after = callbackName
@@ -210,7 +218,7 @@ func sortProcessors(cps []*CallbackProcessor) []*func(scope *Scope) {
 
 // reorder all registered processors, and reset CURD callbacks
 func (c *Callback) reorder() {
-	var creates, updates, deletes, queries, rowQueries []*CallbackProcessor
+	var creates, updates, deletes, queries, rowQueries, trace []*CallbackProcessor
 
 	for _, processor := range c.processors {
 		if processor.name != "" {
@@ -225,6 +233,8 @@ func (c *Callback) reorder() {
 				queries = append(queries, processor)
 			case "row_query":
 				rowQueries = append(rowQueries, processor)
+			case "trace":
+				trace = append(trace, processor)
 			}
 		}
 	}
@@ -234,4 +244,5 @@ func (c *Callback) reorder() {
 	c.deletes = sortProcessors(deletes)
 	c.queries = sortProcessors(queries)
 	c.rowQueries = sortProcessors(rowQueries)
+	c.trace = sortProcessors(trace)
 }

scope.go

@@ -947,6 +947,9 @@ func (scope *Scope) typeName() string {
 
 // trace print sql log
 func (scope *Scope) trace(t time.Time) {
+	scope.Set("gorm:trace-time", t)
+	scope.callCallbacks(scope.db.parent.callbacks.trace)
+
 	if len(scope.SQL) > 0 {
 		scope.db.slog(scope.SQL, t, scope.SQLVars...)
 	}