Code restructuring for db updates.

src/db/gpx.ts

@@ -1,10 +1,5 @@
-import { cloneDeep } from 'lodash';
 import getUri from '../lib/ids';
-
-declare global {
-  var db: any;
-  var dbReady: boolean;
-}
+import { put } from './lib';
 
 const emptyGpx: Gpx = {
   $: {
@@ -38,7 +33,13 @@ const emptyGpx: Gpx = {
 
 export const putNewGpx = (id: string) => {
   const uri = getUri('gpx', { gpx: id });
-  const gpx = cloneDeep(emptyGpx);
+  put(
+    uri,
+    'gpx',
+    (gpx) => {
       gpx.metadata!.time = new Date(Date.now()).toISOString();
-  db.put({ _id: uri, type: 'gpx', doc: gpx });
+      return gpx;
+    },
+    emptyGpx
+  );
 };

src/db/lib.ts

@@ -0,0 +1,32 @@
+import { cloneDeep } from 'lodash';
+
+declare global {
+  var db: any;
+}
+
+export const put = async (
+  _id: string,
+  type: string,
+  update: (doc: any) => any,
+  defaultDoc: any
+) => {
+  var current;
+  try {
+    current = await db.get(_id);
+  } catch {
+    current = { _rev: undefined, doc: cloneDeep(defaultDoc) };
+  }
+  try {
+    db.put({ _id, _rev: current._rev, type, doc: update(current.doc) });
+  } catch (error: any) {
+    if (error.name === 'conflict') {
+      await put(_id, type, update, defaultDoc);
+    } else {
+      console.error(
+        `put(${_id}, ${JSON.stringify(
+          update(current.doc)
+        )}), error: ${JSON.stringify(error)}`
+      );
+    }
+  }
+};