Properly store absent line extra info as null

server/src/database/line.ts

@@ -127,7 +127,7 @@ export default class DatabaseLines {
 					return extraInfo != null ? JSON.parse(extraInfo) : extraInfo;
 				},
 				set: function(this: LineModel, v: ExtraInfo) {
-					this.setDataValue("extraInfo", JSON.stringify(v) as any);
+					this.setDataValue("extraInfo", v != null ? JSON.stringify(v) as any : v);
 				}
 			}
 		}, {

server/src/database/meta.ts

@@ -14,6 +14,7 @@ export interface MetaProperties {
 	hasBboxes: "1";
 	untitledMigrationCompleted: "1";
 	fieldsNullMigrationCompleted: "1";
+	extraInfoNullMigrationCompleted: "1";
 }
 
 export default class DatabaseMeta {

server/src/database/migrations.ts

@@ -25,6 +25,7 @@ export default class DatabaseMigrations {
 		await this._spatialMigration();
 		await this._untitledMigration();
 		await this._fieldsNullMigration();
+		await this._extraInfoNullMigration();
 	}
 
 
@@ -489,4 +490,23 @@ export default class DatabaseMigrations {
 		await this._db.meta.setMeta("fieldsNullMigrationCompleted", "1");
 	}
 
+
+	/** Convert "null" to null for extraInfo */
+	async _extraInfoNullMigration(): Promise<void> {
+		if(await this._db.meta.getMeta("extraInfoNullMigrationCompleted") == "1")
+			return;
+
+		await this._db.lines.LineModel.update({
+			extraInfo: null
+		}, {
+			where: {
+				extraInfo: {
+					[Op.in]: ["null", "{}"]
+				}
+			}
+		});
+
+		await this._db.meta.setMeta("extraInfoNullMigrationCompleted", "1");
+	}
+
 }

server/src/routing/routing.ts

@@ -56,7 +56,7 @@ export async function calculateRouteForLine(line: Pick<Line<CRU.CREATE_VALIDATED
 	} else if(line.mode == "track" && line.trackPoints && line.trackPoints.length >= 2) {
 		result.distance = calculateDistance(line.trackPoints);
 		result.time = undefined;
-		result.extraInfo = {};
+		result.extraInfo = undefined;
 
 		// TODO: ascent/descent?
 
@@ -80,7 +80,7 @@ export async function calculateRouteForLine(line: Pick<Line<CRU.CREATE_VALIDATED
 	} else {
 		result.distance = calculateDistance(line.routePoints);
 		result.time = undefined;
-		result.extraInfo = {};
+		result.extraInfo = undefined;
 
 		result.trackPoints = [ ];
 		for(let i=0; i<line.routePoints.length; i++) {