core: fix problem_edit returns null

packages/hydrooj/package.json

@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.20.15",
+    "version": "2.20.16",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",

packages/hydrooj/src/handler/problem.ts

@@ -323,14 +323,14 @@ export class ProblemEditHandler extends ProblemManageHandler {
     @post('tag', Types.String, true, null, parseCategory)
     async post(
         domainId: string, pid: string | number, title: string, content: string,
-        newPid: string = '', hidden = false, tag: string[],
+        newPid: string = '', hidden = false, tag: string[] = [],
     ) {
         try {
             content = JSON.parse(content);
         } catch { /* Ignore */ }
         if (newPid !== this.pdoc.pid && await problem.get(domainId, newPid)) throw new BadRequestError('new pid exists');
         const $update: Partial<Pdoc> = {
-            title, content, pid: newPid, hidden, tag,
+            title, content, pid: newPid, hidden, tag: tag ?? [],
         };
         let pdoc = await problem.get(domainId, pid);
         await bus.serial('problem/before-edit', $update);
@@ -560,7 +560,7 @@ export class ProblemCreateHandler extends Handler {
             content = JSON.parse(content);
         } catch { /* Ignore */ }
         if (pid && await problem.get(domainId, pid)) throw new BadRequestError('invalid pid');
-        const docId = await problem.add(domainId, pid, title, content, this.user._id, tag, hidden);
+        const docId = await problem.add(domainId, pid, title, content, this.user._id, tag ?? [], hidden);
         this.response.body = { pid: pid || docId };
         this.response.redirect = this.url('problem_files', { pid: pid || docId });
     }

packages/hydrooj/src/upgrade.ts

@@ -200,6 +200,12 @@ const scripts: UpgradeScript[] = [
         });
         return true;
     },
+    // Set null tag to []
+    async function _9_10() {
+        const _FRESH_INSTALL_IGNORE = 1;
+        await db.collection('document').updateMany({ docType: 10, tag: null }, { $set: { tag: [] } });
+        return true;
+    },
 ];
 
 export = scripts;