added document_id for sync identification

app.js

@@ -95,6 +95,11 @@ app.use((req, res, next) => {
 // error handler
 app.use((err, req, res, next) => {
     log.error(err.message);
+
+    res.status(err.status || 500);
+    res.send({
+        message: err.message
+    });
 });
 
 // triggers sync timer

migrations/0017__document_id.sql

@@ -0,0 +1 @@
+INSERT INTO options (opt_name, opt_value) VALUES ('document_id', '');

services/migration.js

@@ -3,7 +3,7 @@ const sql = require('./sql');
 const fs = require('fs-extra');
 const log = require('./log');
 
-const APP_DB_VERSION = 16;
+const APP_DB_VERSION = 17;
 const MIGRATIONS_DIR = "./migrations";
 
 async function migrate() {

services/sql.js

@@ -34,9 +34,14 @@ async function rollback() {
 }
 
 async function getOption(optName) {
-    const row = await getSingleResult("SELECT opt_value FROM options WHERE opt_name = ?", [optName]);
+    try {
+        const row = await getSingleResult("SELECT opt_value FROM options WHERE opt_name = ?", [optName]);
 
-    return row['opt_value'];
+        return row['opt_value'];
+    }
+    catch (e) {
+        throw new Error("Option " + optName + " doesn't exist");
+    }
 }
 
 async function setOption(optName, optValue) {

services/sync.js

@@ -112,6 +112,7 @@ async function sync() {
 
 async function getChangedSince(since) {
     return {
+        'documentId': await getDocumentId(),
         'syncTimestamp': utils.nowTimestamp(),
         'tree': await sql.getResults("select * from notes_tree where date_modified >= ?", [since]),
         'notes': await sql.getFlattenedResults('note_id', "select note_id from notes where date_modified >= ?", [since]),
@@ -167,6 +168,22 @@ async function putNote(note) {
     log.info("Update/sync note " + note.detail.note_id);
 }
 
+let documentIdCache = null;
+
+async function getDocumentId() {
+    if (!documentIdCache) {
+        documentIdCache = await sql.getOption('document_id');
+
+        if (!documentIdCache) {
+            documentIdCache = utils.randomString(16);
+
+            await sql.setOption('document_id', documentIdCache);
+        }
+    }
+
+    return documentIdCache;
+}
+
 if (SYNC_SERVER) {
     log.info("Setting up sync");
 

services/utils.js

@@ -6,7 +6,7 @@ function newNoteId() {
 
 const ALPHA_NUMERIC = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
 
-function randomString(length, chars) {
+function randomString(length) {
     let result = '';
 
     for (let i = length; i > 0; --i) {