Fix contest bugs

models/contest.js

@@ -69,6 +69,7 @@ class Contest extends Model {
   static async create(val) {
     return Contest.fromRecord(Contest.model.build(Object.assign({
       title: '',
+      problems: '',
       start_time: 0,
       end_time: 0,
       holder: 0,
@@ -90,6 +91,7 @@ class Contest extends Model {
   }
 
   async getProblems() {
+    if (this.problems === '') return [];
     return this.problems.split('|').map(x => parseInt(x));
   }
 

modules/contest.js

@@ -53,9 +53,11 @@ app.get('/contest/:id/edit', async (req, res) => {
     let contest = await Contest.fromID(contest_id);
     if (!contest) {
       contest = await Contest.create();
+      contest.id = 0;
     }
 
-    let problems = await contest.problems.split('|').mapAsync(async id => await Problem.fromID(id));
+    let problems = [];
+    if (contest.problems) problems = await contest.problems.split('|').mapAsync(async id => await Problem.fromID(id));
 
     res.render('edit_contest', {
       contest: contest,