Fix duplicate key checks in SQLite

Ref T529

database.go

@@ -8,6 +8,8 @@ import (
 	"time"
 
 	"github.com/go-sql-driver/mysql"
+	"github.com/mattn/go-sqlite3"
+
 	"github.com/guregu/null"
 	"github.com/guregu/null/zero"
 	uuid "github.com/nu7hatch/gouuid"
@@ -130,6 +132,22 @@ func (db *datastore) upsert(indexedCols ...string) string {
 	return "ON DUPLICATE KEY UPDATE"
 }
 
+func (db *datastore) isDuplicateKeyErr(err error) bool {
+	if db.driverName == driverSQLite {
+		if err, ok := err.(sqlite3.Error); ok {
+			return err.Code == sqlite3.ErrConstraint
+		}
+	} else if db.driverName == driverMySQL {
+		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+			return mysqlErr.Number == mySQLErrDuplicateKey
+		}
+	} else {
+		log.Error("isDuplicateKeyErr: failed check for unrecognized driver '%s'", db.driverName)
+	}
+
+	return false
+}
+
 func (db *datastore) CreateUser(u *User, collectionTitle string) error {
 	// New users get a `users` and `collections` row.
 	t, err := db.Begin()
@@ -146,11 +164,9 @@ func (db *datastore) CreateUser(u *User, collectionTitle string) error {
 	res, err := t.Exec("INSERT INTO users (username, password, email) VALUES (?, ?, ?)", u.Username, u.HashedPass, u.Email)
 	if err != nil {
 		t.Rollback()
-		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+		if db.isDuplicateKeyErr(err) {
-			if mysqlErr.Number == mySQLErrDuplicateKey {
 			return impart.HTTPError{http.StatusConflict, "Username is already taken."}
 		}
-		}
 
 		log.Error("Rolling back users INSERT: %v\n", err)
 		return err
@@ -169,11 +185,9 @@ func (db *datastore) CreateUser(u *User, collectionTitle string) error {
 	res, err = t.Exec("INSERT INTO collections (alias, title, description, privacy, owner_id, view_count) VALUES (?, ?, ?, ?, ?, ?)", u.Username, collectionTitle, "", CollUnlisted, u.ID, 0)
 	if err != nil {
 		t.Rollback()
-		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+		if db.isDuplicateKeyErr(err) {
-			if mysqlErr.Number == mySQLErrDuplicateKey {
 			return impart.HTTPError{http.StatusConflict, "Username is already taken."}
 		}
-		}
 		log.Error("Rolling back collections INSERT: %v\n", err)
 		return err
 	}
@@ -241,11 +255,9 @@ func (db *datastore) CreateCollection(alias, title string, userID int64) (*Colle
 	// All good, so create new collection
 	res, err := db.Exec("INSERT INTO collections (alias, title, description, privacy, owner_id, view_count) VALUES (?, ?, ?, ?, ?, ?)", alias, title, "", CollUnlisted, userID, 0)
 	if err != nil {
-		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+		if db.isDuplicateKeyErr(err) {
-			if mysqlErr.Number == mySQLErrDuplicateKey {
 			return nil, impart.HTTPError{http.StatusConflict, "Collection already exists."}
 		}
-		}
 		log.Error("Couldn't add to collections: %v\n", err)
 		return nil, err
 	}
@@ -614,8 +626,7 @@ func (db *datastore) CreatePost(userID, collID int64, post *SubmittedPost) (*Pos
 	defer stmt.Close()
 	_, err = stmt.Exec(friendlyID, slug, post.Title, post.Content, appearance, post.Language, post.IsRTL, 0, ownerID, ownerCollID, created, 0)
 	if err != nil {
-		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+		if db.isDuplicateKeyErr(err) {
-			if mysqlErr.Number == mySQLErrDuplicateKey {
 			// Duplicate entry error; try a new slug
 			// TODO: make this a little more robust
 			slug = sql.NullString{id.GenSafeUniqueSlug(slug.String), true}
@@ -626,9 +637,6 @@ func (db *datastore) CreatePost(userID, collID int64, post *SubmittedPost) (*Pos
 		} else {
 			return nil, handleFailedPostInsert(err)
 		}
-		} else {
-			return nil, handleFailedPostInsert(err)
-		}
 	}
 
 	// TODO: return Created field in proper format
@@ -1198,8 +1206,7 @@ func (db *datastore) CanCollect(cpr *ClaimPostRequest, userID int64) bool {
 func (db *datastore) AttemptClaim(p *ClaimPostRequest, query string, params []interface{}, slugIdx int) (sql.Result, error) {
 	qRes, err := db.Exec(query, params...)
 	if err != nil {
-		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+		if db.isDuplicateKeyErr(err) && slugIdx > -1 {
-			if mysqlErr.Number == mySQLErrDuplicateKey && slugIdx > -1 {
 			s := id.GenSafeUniqueSlug(p.Slug)
 			if s == p.Slug {
 				// Sanity check to prevent infinite recursion
@@ -1209,7 +1216,6 @@ func (db *datastore) AttemptClaim(p *ClaimPostRequest, query string, params []in
 			params[slugIdx] = p.Slug
 			return db.AttemptClaim(p, query, params, slugIdx)
 		}
-		}
 		return qRes, fmt.Errorf("attemptClaim: %s", err)
 	}
 	return qRes, nil
@@ -1779,11 +1785,9 @@ func (db *datastore) ChangeSettings(app *app, u *User, s *userSettings) error {
 		_, err = t.Exec("UPDATE users SET username = ? WHERE id = ?", newUsername, u.ID)
 		if err != nil {
 			t.Rollback()
-			if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+			if db.isDuplicateKeyErr(err) {
-				if mysqlErr.Number == mySQLErrDuplicateKey {
 				return impart.HTTPError{http.StatusConflict, "Username is already taken."}
 			}
-			}
 			log.Error("Unable to update users table: %v", err)
 			return ErrInternalGeneral
 		}
@@ -1791,11 +1795,9 @@ func (db *datastore) ChangeSettings(app *app, u *User, s *userSettings) error {
 		_, err = t.Exec("UPDATE collections SET alias = ? WHERE alias = ? AND owner_id = ?", newUsername, u.Username, u.ID)
 		if err != nil {
 			t.Rollback()
-			if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+			if db.isDuplicateKeyErr(err) {
-				if mysqlErr.Number == mySQLErrDuplicateKey {
 				return impart.HTTPError{http.StatusConflict, "Username is already taken."}
 			}
-			}
 			log.Error("Unable to update collection: %v", err)
 			return ErrInternalGeneral
 		}