Remove NewSession method from db.Engine interface (#17577)

* Remove NewSession method from db.Engine interface

* Fix bug

* Some improvements

* Fix bug

* Fix test

* Use XXXBean instead of XXXExample

models/pull.go

@@ -285,11 +285,12 @@ func (pr *PullRequest) getReviewedByLines(writer io.Writer) error {
 		return nil
 	}
 
-	sess := db.NewSession(db.DefaultContext)
-	defer sess.Close()
-	if err := sess.Begin(); err != nil {
+	ctx, committer, err := db.TxContext()
+	if err != nil {
 		return err
 	}
+	defer committer.Close()
+	sess := db.GetEngine(ctx)
 
 	// Note: This doesn't page as we only expect a very limited number of reviews
 	reviews, err := findReviews(sess, FindReviewOptions{
@@ -326,7 +327,7 @@ func (pr *PullRequest) getReviewedByLines(writer io.Writer) error {
 		}
 		reviewersWritten++
 	}
-	return sess.Commit()
+	return committer.Commit()
 }
 
 // GetDefaultSquashMessage returns default message used when squash and merging pull request