diff --git a/packages/hydrooj/src/handler/contest.ts b/packages/hydrooj/src/handler/contest.ts
index b076955de..060e9f292 100644
--- a/packages/hydrooj/src/handler/contest.ts
+++ b/packages/hydrooj/src/handler/contest.ts
@@ -115,7 +115,7 @@ class ContestBoardcastHandler extends ContestHandler {
     }
 
     @param('tid', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async post(domainId: string, tid: ObjectID, content: string) {
         const tdoc = await contest.get(domainId, tid);
         if (tdoc.owner !== this.user._id) throw new PermissionError('Boardcast Message');
@@ -202,10 +202,10 @@ class ContestEditHandler extends ContestHandler {
     @param('beginAtDate', Types.Date)
     @param('beginAtTime', Types.Time)
     @param('duration', Types.Float)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
     @param('rule', Types.Range(contest.RULES))
-    @param('pids', Types.String)
+    @param('pids', Types.Content)
     @param('rated', Types.Boolean)
     async post(
         domainId: string, beginAtDate: string, beginAtTime: string, duration: number,
@@ -284,7 +284,7 @@ class ContestProblemHandler extends ContestHandler {
 
 export class ContestProblemFileDownloadHandler extends ContestProblemHandler {
     @query('type', Types.Range(['additional_file', 'testdata']), true)
-    @param('filename', Types.String)
+    @param('filename', Types.Name)
     @param('noDisposition', Types.Boolean)
     async get(domainId: string, type = 'additional_file', filename: string, noDisposition = false) {
         if (type === 'testdata' && this.user._id !== this.pdoc.owner) this.checkPerm(PERM.PERM_READ_PROBLEM_DATA);
@@ -327,8 +327,8 @@ class ContestDetailProblemSubmitHandler extends ContestProblemHandler {
     }
 
     @param('tid', Types.ObjectID)
-    @param('lang', Types.String)
-    @param('code', Types.String)
+    @param('lang', Types.Name)
+    @param('code', Types.Content)
     async post(domainId: string, tid: ObjectID, lang: string, code: string) {
         await this.limitRate('add_record', 60, 10);
         const rid = await record.add(domainId, this.pdoc.docId, this.user._id, lang, code, true, {
@@ -406,10 +406,10 @@ class ContestCreateHandler extends ContestHandler {
     @param('beginAtDate', Types.Date)
     @param('beginAtTime', Types.Time)
     @param('duration', Types.Float)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
-    @param('rule', Types.String)
-    @param('pids', Types.String)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
+    @param('rule', Types.Name)
+    @param('pids', Types.Content)
     @param('rated', Types.Boolean)
     async post(
         domainId: string, beginAtDate: string, beginAtTime: string, duration: number,
diff --git a/packages/hydrooj/src/handler/discussion.ts b/packages/hydrooj/src/handler/discussion.ts
index 27c679965..d4fde2afc 100644
--- a/packages/hydrooj/src/handler/discussion.ts
+++ b/packages/hydrooj/src/handler/discussion.ts
@@ -32,8 +32,8 @@ class DiscussionHandler extends Handler {
     drrdoc?: Drrdoc;
     vnode?: any;
 
-    @param('type', Types.String, true)
-    @param('name', Types.String, true)
+    @param('type', Types.Name, true)
+    @param('name', Types.Name, true)
     @param('did', Types.ObjectID, true)
     @param('drid', Types.ObjectID, true)
     @param('drrid', Types.ObjectID, true)
@@ -97,8 +97,8 @@ class DiscussionMainHandler extends Handler {
 }
 
 class DiscussionNodeHandler extends DiscussionHandler {
-    @param('type', Types.String)
-    @param('name', Types.String)
+    @param('type', Types.Name)
+    @param('name', Types.Name)
     @param('page', Types.PositiveInt, true)
     async get(domainId: string, type: string, _name: string, page = 1) {
         let name: ObjectID | string | number;
@@ -149,10 +149,10 @@ class DiscussionCreateHandler extends DiscussionHandler {
         this.response.body = { path, vnode: this.vnode };
     }
 
-    @param('type', Types.String)
-    @param('name', Types.String)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
+    @param('type', Types.Name)
+    @param('name', Types.Name)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
     @param('highlight', Types.Boolean)
     @param('pin', Types.Boolean)
     async post(
@@ -166,11 +166,6 @@ class DiscussionCreateHandler extends DiscussionHandler {
         else name = _name;
         if (highlight) this.checkPerm(PERM.PERM_HIGHLIGHT_DISCUSSION);
         if (pin) this.checkPerm(PERM.PERM_PIN_DISCUSSION);
-        await bus.serial(
-            'discussion/before-add',
-            domainId, typeMapper[type], name, this.user._id,
-            title, content, this.request.ip, highlight, pin,
-        );
         const did = await discussion.add(
             domainId, typeMapper[type], name, this.user._id,
             title, content, this.request.ip, highlight, pin,
@@ -217,7 +212,7 @@ class DiscussionDetailHandler extends DiscussionHandler {
     }
 
     @param('did', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postReply(domainId: string, did: ObjectID, content: string) {
         this.checkPerm(PERM.PERM_REPLY_DISCUSSION);
         await this.limitRate('add_discussion', 3600, 60);
@@ -236,7 +231,7 @@ class DiscussionDetailHandler extends DiscussionHandler {
     }
 
     @param('drid', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postTailReply(domainId: string, drid: ObjectID, content: string) {
         this.checkPerm(PERM.PERM_REPLY_DISCUSSION);
         await this.limitRate('add_discussion', 3600, 60);
@@ -245,7 +240,7 @@ class DiscussionDetailHandler extends DiscussionHandler {
     }
 
     @param('drid', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postEditReply(domainId: string, drid: ObjectID, content: string) {
         this.checkPerm(PERM.PERM_EDIT_DISCUSSION_REPLY_SELF);
         if (this.drdoc.owner !== this.user._id) throw new PermissionError(PERM.PERM_EDIT_DISCUSSION_REPLY_SELF);
@@ -268,7 +263,7 @@ class DiscussionDetailHandler extends DiscussionHandler {
 
     @param('drid', Types.ObjectID)
     @param('drrid', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postEditTailReply(domainId: string, drid: ObjectID, drrid: ObjectID, content: string) {
         this.checkPerm(PERM.PERM_EDIT_DISCUSSION_REPLY_SELF);
         if (this.drdoc.owner !== this.user._id) throw new PermissionError(PERM.PERM_EDIT_DISCUSSION_REPLY_SELF);
@@ -333,8 +328,8 @@ class DiscussionEditHandler extends DiscussionHandler {
     }
 
     @param('did', Types.ObjectID)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
     @param('highlight', Types.Boolean)
     @param('pin', Types.Boolean)
     async postUpdate(
diff --git a/packages/hydrooj/src/handler/domain.ts b/packages/hydrooj/src/handler/domain.ts
index 872bb9b3f..a7abc5da3 100644
--- a/packages/hydrooj/src/handler/domain.ts
+++ b/packages/hydrooj/src/handler/domain.ts
@@ -130,14 +130,14 @@ class DomainUserHandler extends ManageHandler {
     }
 
     @post('uid', Types.Int)
-    @post('role', Types.String)
+    @post('role', Types.Name)
     async postSetUser(domainId: string, uid: number, role: string) {
         await domain.setUserRole(domainId, uid, role);
         this.back();
     }
 
     @param('uid', Types.NumericArray)
-    @param('role', Types.String)
+    @param('role', Types.Name)
     async postSetUsers(domainId: string, uid: number[], role: string) {
         await domain.setUserRole(domainId, uid, role);
         this.back();
@@ -187,7 +187,7 @@ class DomainRoleHandler extends ManageHandler {
         this.response.body = { roles, domain: this.domain, path };
     }
 
-    @param('role', Types.String)
+    @param('role', Types.Name)
     async postAdd(domainId: string, role: string) {
         const roles = await domain.getRoles(this.domain);
         const rdict: Dictionary<any> = {};
@@ -229,9 +229,9 @@ class DomainJoinApplicationsHandler extends ManageHandler {
     }
 
     @post('method', Types.Range([domain.JOIN_METHOD_NONE, domain.JOIN_METHOD_ALL, domain.JOIN_METHOD_CODE]))
-    @post('role', Types.String, true)
+    @post('role', Types.Name, true)
     @post('expire', Types.Int, true)
-    @post('invitationCode', Types.String, true)
+    @post('invitationCode', Types.Content, true)
     async post(domainId: string, method: number, role: string, expire: number, invitationCode = '') {
         const r = await domain.getRoles(this.domain);
         const roles = r.map((rl) => rl._id);
@@ -269,7 +269,7 @@ class DomainJoinHandler extends Handler {
         if (this.user.role !== 'default') throw new DomainJoinAlreadyMemberError(this.domain._id, this.user._id);
     }
 
-    @param('code', Types.String, true)
+    @param('code', Types.Content, true)
     async get(domainId: string, code: string) {
         this.response.template = 'domain_join.html';
         this.response.body.joinSettings = this.joinSettings;
@@ -280,7 +280,7 @@ class DomainJoinHandler extends Handler {
         ];
     }
 
-    @param('code', Types.String, true)
+    @param('code', Types.Content, true)
     async post(domainId: string, code: string) {
         if (this.joinSettings.method === domain.JOIN_METHOD_CODE) {
             if (this.joinSettings.code !== code) {
@@ -293,7 +293,7 @@ class DomainJoinHandler extends Handler {
 }
 
 class DomainSearchHandler extends Handler {
-    @param('q', Types.String)
+    @param('q', Types.Content)
     async get(domainId: string, q: string) {
         const ddocs = await domain.getPrefixSearch(q, 20);
         for (let i = 0; i < ddocs.length; i++) {
diff --git a/packages/hydrooj/src/handler/home.ts b/packages/hydrooj/src/handler/home.ts
index 4436abe98..4b3ec8dcc 100644
--- a/packages/hydrooj/src/handler/home.ts
+++ b/packages/hydrooj/src/handler/home.ts
@@ -151,7 +151,7 @@ class HomeSecurityHandler extends Handler {
     }
 
     @param('currentPassword', Types.String)
-    @param('mail', Types.String, isEmail)
+    @param('mail', Types.Name, isEmail)
     async postChangeMail(domainId: string, current: string, email: string) {
         await this.limitRate('send_mail', 3600, 30);
         this.user.checkPassword(current);
@@ -191,7 +191,7 @@ class HomeSecurityHandler extends Handler {
 }
 
 class HomeSettingsHandler extends Handler {
-    @param('category', Types.String)
+    @param('category', Types.Name)
     async get(domainId: string, category: string) {
         const path = [
             ['Hydro', 'homepage'],
@@ -287,10 +287,10 @@ class HomeDomainCreateHandler extends Handler {
         this.response.template = 'domain_create.html';
     }
 
-    @param('id', Types.String)
-    @param('name', Types.String, isTitle)
-    @param('bulletin', Types.String, isContent)
-    @param('gravatar', Types.String, true, isEmail)
+    @param('id', Types.Name)
+    @param('name', Types.Title)
+    @param('bulletin', Types.Content)
+    @param('gravatar', Types.Content, true, isEmail)
     async post(_: string, id: string, name: string, bulletin: string, gravatar: string) {
         const doc = await domain.get(id);
         if (doc) throw new DomainAlreadyExistsError(id);
@@ -335,7 +335,7 @@ class HomeMessagesHandler extends Handler {
     }
 
     @param('uid', Types.Int)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postSend(domainId: string, uid: number, content: string) {
         const udoc = await user.getById('system', uid);
         if (!udoc) throw new UserNotFoundError(uid);
diff --git a/packages/hydrooj/src/handler/homework.ts b/packages/hydrooj/src/handler/homework.ts
index 6763fd8a3..4c6f4c83c 100644
--- a/packages/hydrooj/src/handler/homework.ts
+++ b/packages/hydrooj/src/handler/homework.ts
@@ -174,8 +174,8 @@ class HomeworkDetailProblemSubmitHandler extends HomeworkDetailProblemHandler {
 
     @param('tid', Types.ObjectID)
     @param('pid', Types.UnsignedInt)
-    @param('code', Types.String)
-    @param('lang', Types.String)
+    @param('code', Types.Content)
+    @param('lang', Types.Name)
     async post(domainId: string, tid: ObjectID, pid: number, code: string, lang: string) {
         await this.limitRate('add_record', 60, 5);
         const tsdoc = await contest.getStatus(domainId, tid, this.user._id, document.TYPE_HOMEWORK);
@@ -227,10 +227,10 @@ class HomeworkCreateHandler extends HomeworkHandler {
     @param('penaltySinceDate', Types.Date)
     @param('penaltySinceTime', Types.Time)
     @param('extensionDays', Types.Float)
-    @param('penaltyRules', Types.String, validatePenaltyRules, convertPenaltyRules)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
-    @param('pids', Types.String)
+    @param('penaltyRules', Types.Content, validatePenaltyRules, convertPenaltyRules)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
+    @param('pids', Types.Content)
     @param('rated', Types.Boolean)
     async post(
         domainId: string, beginAtDate: string, beginAtTime: string,
@@ -294,10 +294,10 @@ class HomeworkEditHandler extends HomeworkHandler {
     @param('penaltySinceDate', Types.Date)
     @param('penaltySinceTime', Types.Time)
     @param('extensionDays', Types.Float)
-    @param('penaltyRules', Types.String, validatePenaltyRules, convertPenaltyRules)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
-    @param('pids', Types.String)
+    @param('penaltyRules', Types.Content, validatePenaltyRules, convertPenaltyRules)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
+    @param('pids', Types.Content)
     @param('rated', Types.Boolean)
     async post(
         domainId: string, tid: ObjectID, beginAtDate: string, beginAtTime: string,
@@ -364,7 +364,7 @@ class HomeworkScoreboardHandler extends HomeworkHandler {
 
 class HomeworkScoreboardDownloadHandler extends HomeworkHandler {
     @param('tid', Types.ObjectID)
-    @param('ext', Types.String)
+    @param('ext', Types.Name)
     async get(domainId: string, tid: ObjectID, ext: string) {
         const getContent = {
             csv: (rows) => `\uFEFF${rows.map((c) => (c.map((i) => i.value).join(','))).join('\n')}`,
diff --git a/packages/hydrooj/src/handler/import.syzoj.ts b/packages/hydrooj/src/handler/import.syzoj.ts
index eb43f6b1e..d06f6be78 100644
--- a/packages/hydrooj/src/handler/import.syzoj.ts
+++ b/packages/hydrooj/src/handler/import.syzoj.ts
@@ -220,10 +220,10 @@ class ProblemImportSYZOJHandler extends Handler {
         return docId;
     }
 
-    @post('url', Types.String, true)
-    @post('pid', Types.String, true, isPid)
+    @post('url', Types.Content, true)
+    @post('pid', Types.Name, true, isPid)
     @post('hidden', Types.Boolean)
-    @post('prefix', Types.String, true)
+    @post('prefix', Types.Name, true)
     @post('start', Types.UnsignedInt, true)
     @post('end', Types.UnsignedInt, true)
     async post(
diff --git a/packages/hydrooj/src/handler/manage.ts b/packages/hydrooj/src/handler/manage.ts
index 6c23807cc..6bef43af3 100644
--- a/packages/hydrooj/src/handler/manage.ts
+++ b/packages/hydrooj/src/handler/manage.ts
@@ -102,8 +102,8 @@ class SystemScriptHandler extends SystemHandler {
         this.response.body.path.push(['manage_script', null]);
     }
 
-    @param('id', Types.String)
-    @param('args', Types.String, true)
+    @param('id', Types.Name)
+    @param('args', Types.Content, true)
     async post(domainId: string, id: string, raw = '{}') {
         if (!global.Hydro.script[id]) throw new ValidationError('id');
         const args = JSON.parse(raw);
@@ -189,7 +189,7 @@ class SystemUserImportHandler extends SystemHandler {
         this.response.template = 'manage_user_import.html';
     }
 
-    @param('users', Types.String)
+    @param('users', Types.Content)
     @param('draft', Types.Boolean)
     async post(domainId: string, _users: string, draft: boolean) {
         const users = _users.split('\n');
diff --git a/packages/hydrooj/src/handler/misc.ts b/packages/hydrooj/src/handler/misc.ts
index 8a7b5217f..ba42112db 100644
--- a/packages/hydrooj/src/handler/misc.ts
+++ b/packages/hydrooj/src/handler/misc.ts
@@ -36,7 +36,7 @@ class CheckInHandler extends Handler {
 }
 
 class SwitchLanguageHandler extends Handler {
-    @param('lang', Types.String)
+    @param('lang', Types.Name)
     async get(domainId: string, lang: string) {
         if (this.user.hasPriv(PRIV.PRIV_USER_PROFILE)) {
             this.session.viewLang = lang;
diff --git a/packages/hydrooj/src/handler/problem.ts b/packages/hydrooj/src/handler/problem.ts
index de62c4bad..8e83e7ffa 100644
--- a/packages/hydrooj/src/handler/problem.ts
+++ b/packages/hydrooj/src/handler/problem.ts
@@ -53,7 +53,7 @@ export class ProblemHandler extends Handler {
 
 export class ProblemMainHandler extends ProblemHandler {
     @param('page', Types.PositiveInt, true)
-    @param('q', Types.String, true)
+    @param('q', Types.Content, true)
     async get(domainId: string, page = 1, q = '') {
         this.response.template = 'problem_main.html';
         // eslint-disable-next-line @typescript-eslint/no-shadow
@@ -112,7 +112,7 @@ export class ProblemMainHandler extends ProblemHandler {
 
 export class ProblemCategoryHandler extends ProblemHandler {
     @param('page', Types.PositiveInt, true)
-    @param('category', Types.String, null, parseCategory)
+    @param('category', Types.Name, null, parseCategory)
     async get(domainId: string, page = 1, category: string[]) {
         this.response.template = 'problem_main.html';
         const q: any = { $and: [] };
@@ -143,7 +143,7 @@ export class ProblemCategoryHandler extends ProblemHandler {
 }
 
 export class ProblemRandomHandler extends ProblemHandler {
-    @param('category', Types.String, true, null, parseCategory)
+    @param('category', Types.Name, true, null, parseCategory)
     async get(domainId: string, category: string[] = []) {
         const q: FilterQuery<Pdoc> = category.length ? { $and: [] } : {};
         for (const tag of category) q.$and.push({ tag });
@@ -160,7 +160,7 @@ export class ProblemDetailHandler extends ProblemHandler {
     pdoc: Pdoc;
     udoc: User;
 
-    @route('pid', Types.String, true, null, parsePid)
+    @route('pid', Types.Name, true, null, parsePid)
     async _prepare(domainId: string, pid: number | string) {
         this.response.template = 'problem_detail.html';
         this.pdoc = await problem.get(domainId, pid, this.user._id);
@@ -210,7 +210,7 @@ export class ProblemDetailHandler extends ProblemHandler {
 }
 
 export class ProblemSubmitHandler extends ProblemDetailHandler {
-    @param('pid', Types.String, null, parsePid)
+    @param('pid', Types.Name, null, parsePid)
     async get(domainId: string, pid: string | number) {
         this.response.template = 'problem_submit.html';
         const rdocs = await record
@@ -232,8 +232,8 @@ export class ProblemSubmitHandler extends ProblemDetailHandler {
         };
     }
 
-    @param('lang', Types.String)
-    @param('code', Types.String)
+    @param('lang', Types.Name)
+    @param('code', Types.Content)
     async post(domainId: string, lang: string, code: string) {
         await this.limitRate('add_record', 60, 5);
         const rid = await record.add(domainId, this.pdoc.docId, this.user._id, lang, code, true);
@@ -250,9 +250,9 @@ export class ProblemSubmitHandler extends ProblemDetailHandler {
 }
 
 export class ProblemPretestHandler extends ProblemDetailHandler {
-    @param('lang', Types.String)
-    @param('code', Types.String)
-    @param('input', Types.String, true)
+    @param('lang', Types.Name)
+    @param('code', Types.Content)
+    @param('input', Types.Content, true)
     async post(domainId: string, lang: string, code: string, input = '') {
         await this.limitRate('add_record', 60, 5);
         const rid = await record.add(
@@ -270,7 +270,7 @@ export class ProblemPretestConnectionHandler extends ConnectionHandler {
     domainId: string;
     dispose: bus.Disposable;
 
-    @param('pid', Types.String)
+    @param('pid', Types.Name)
     async prepare(domainId: string, pid: string) {
         const pdoc = await problem.get(domainId, pid);
         if (!pdoc) throw new ProblemNotFoundError(domainId, pid);
@@ -327,12 +327,12 @@ export class ProblemEditHandler extends ProblemManageHandler {
         ];
     }
 
-    @route('pid', Types.String, null, parsePid)
-    @post('title', Types.String, isTitle)
-    @post('content', Types.String, isContent)
-    @post('pid', Types.String, isPid, true)
+    @route('pid', Types.Name, null, parsePid)
+    @post('content', Types.Title)
+    @post('content', Types.Content)
+    @post('pid', Types.Name, isPid, true)
     @post('hidden', Types.Boolean)
-    @post('tag', Types.String, true, null, parseCategory)
+    @post('tag', Types.Content, true, null, parseCategory)
     async post(
         domainId: string, pid: string | number, title: string, content: string,
         newPid: string = '', hidden = false, tag: string[] = [],
@@ -375,8 +375,8 @@ export class ProblemFilesHandler extends ProblemDetailHandler {
         this.response.body.links = links;
     }
 
-    @post('filename', Types.String)
-    @post('type', Types.String, true)
+    @post('filename', Types.Name)
+    @post('type', Types.Content, true)
     async postUploadFile(domainId: string, filename: string, type = 'testdata') {
         if (!this.request.files.file) throw new ValidationError('file');
         if (this.pdoc.owner !== this.user._id) this.checkPerm(PERM.PERM_EDIT_PROBLEM);
@@ -413,7 +413,7 @@ export class ProblemFilesHandler extends ProblemDetailHandler {
 
 export class ProblemFileDownloadHandler extends ProblemDetailHandler {
     @query('type', Types.Range(['additional_file', 'testdata']), true)
-    @param('filename', Types.String)
+    @param('filename', Types.Name)
     @param('noDisposition', Types.Boolean)
     async get(domainId: string, type = 'additional_file', filename: string, noDisposition = false) {
         if (type === 'testdata' && this.user._id !== this.pdoc.owner) this.checkPerm(PERM.PERM_READ_PROBLEM_DATA);
@@ -456,14 +456,14 @@ export class ProblemSolutionHandler extends ProblemDetailHandler {
         await bus.serial('handler/solution/get', this);
     }
 
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postSubmit(domainId: string, content: string) {
         this.checkPerm(PERM.PERM_CREATE_PROBLEM_SOLUTION);
         await solution.add(domainId, this.pdoc.docId, this.user._id, content);
         this.back();
     }
 
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     @param('psid', Types.ObjectID)
     async postEditSolution(domainId: string, content: string, psid: ObjectID) {
         let psdoc = await solution.get(domainId, psid);
@@ -483,7 +483,7 @@ export class ProblemSolutionHandler extends ProblemDetailHandler {
     }
 
     @param('psid', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postReply(domainId: string, psid: ObjectID, content: string) {
         this.checkPerm(PERM.PERM_REPLY_PROBLEM_SOLUTION);
         const psdoc = await solution.get(domainId, psid);
@@ -493,7 +493,7 @@ export class ProblemSolutionHandler extends ProblemDetailHandler {
 
     @param('psid', Types.ObjectID)
     @param('psrid', Types.ObjectID)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Content)
     async postEditReply(domainId: string, psid: ObjectID, psrid: ObjectID, content: string) {
         const [psdoc, psrdoc] = await solution.getReply(domainId, psid, psrid);
         if ((!psdoc) || psdoc.pid !== this.pdoc.docId) throw new SolutionNotFoundError(psid);
@@ -561,11 +561,11 @@ export class ProblemCreateHandler extends Handler {
         };
     }
 
-    @post('title', Types.String, isTitle)
-    @post('content', Types.String, isContent)
-    @post('pid', Types.String, true, isPid)
+    @post('content', Types.Title)
+    @post('content', Types.Content)
+    @post('pid', Types.Name, true, isPid)
     @post('hidden', Types.Boolean)
-    @post('tag', Types.String, true, null, parseCategory)
+    @post('tag', Types.Content, true, null, parseCategory)
     async post(domainId: string, title: string, content: string, pid: string, hidden = false, tag: string[] = []) {
         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);
diff --git a/packages/hydrooj/src/handler/record.ts b/packages/hydrooj/src/handler/record.ts
index 6b30042da..f3c91782d 100644
--- a/packages/hydrooj/src/handler/record.ts
+++ b/packages/hydrooj/src/handler/record.ts
@@ -18,9 +18,9 @@ const RecordHandler = contest.ContestHandlerMixin(Handler);
 
 class RecordListHandler extends RecordHandler {
     @param('page', Types.PositiveInt, true)
-    @param('pid', Types.String, true)
+    @param('pid', Types.Name, true)
     @param('tid', Types.ObjectID, true)
-    @param('uidOrName', Types.String, true)
+    @param('uidOrName', Types.Name, true)
     @param('allDomain', Types.Boolean, true)
     async get(domainId: string, page = 1, pid?: string, tid?: ObjectID, uidOrName?: string, all = false) {
         this.response.template = 'record_main.html';
diff --git a/packages/hydrooj/src/handler/remote.ts b/packages/hydrooj/src/handler/remote.ts
index 6df671289..ad521437b 100644
--- a/packages/hydrooj/src/handler/remote.ts
+++ b/packages/hydrooj/src/handler/remote.ts
@@ -50,7 +50,7 @@ export class ProblemSendHandler extends Handler {
         this.back();
     }
 
-    @post('token', Types.String)
+    @post('token', Types.Content)
     async postInfo(domainId: string, tokenId: string) {
         const data = await token.get(tokenId, token.TYPE_EXPORT);
         if (!data) throw new InvalidTokenError(tokenId);
@@ -60,7 +60,7 @@ export class ProblemSendHandler extends Handler {
         this.response.body = { pdocs: r, pids: data.pids };
     }
 
-    @post('token', Types.String, true)
+    @post('token', Types.Content, true)
     @post('pids', Types.Array)
     async postFetch(domainId: string, tokenId: string, pids: number[]) {
         pids = pids.map((i) => (+i ? +i : i));
diff --git a/packages/hydrooj/src/handler/training.ts b/packages/hydrooj/src/handler/training.ts
index 443cfa279..c78017ded 100644
--- a/packages/hydrooj/src/handler/training.ts
+++ b/packages/hydrooj/src/handler/training.ts
@@ -178,8 +178,8 @@ class TrainingCreateHandler extends Handler {
         this.response.body = { page_name: 'training_create', path };
     }
 
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
     @param('dag', Types.String, isContent)
     @param('description', Types.String, isDescription)
     async post(
@@ -224,8 +224,8 @@ class TrainingEditHandler extends Handler {
     }
 
     @param('tid', Types.ObjectID)
-    @param('title', Types.String, isTitle)
-    @param('content', Types.String, isContent)
+    @param('content', Types.Title)
+    @param('content', Types.Content)
     @param('dag', Types.String, isContent)
     @param('description', Types.String, isDescription)
     async post(
diff --git a/packages/hydrooj/src/model/discussion.ts b/packages/hydrooj/src/model/discussion.ts
index 8ce83d393..24492fee1 100644
--- a/packages/hydrooj/src/model/discussion.ts
+++ b/packages/hydrooj/src/model/discussion.ts
@@ -1,4 +1,5 @@
 import { FilterQuery, ObjectID } from 'mongodb';
+import { omit } from 'lodash';
 import problem from './problem';
 import * as contest from './contest';
 import * as training from './training';
@@ -63,24 +64,33 @@ export const typeDisplay = {
     [document.TYPE_HOMEWORK]: 'homework',
 };
 
-export function add(
+export async function add(
     domainId: string, parentType: number, parentId: ObjectID | number | string,
     owner: number, title: string, content: string,
     ip: string | null = null, highlight: boolean, pin: boolean,
 ): Promise<ObjectID> {
-    return document.add(
-        domainId, content, owner, document.TYPE_DISCUSSION,
-        null, parentType, parentId,
-        {
-            title,
-            ip,
-            nReply: 0,
-            highlight,
-            pin,
-            updateAt: new Date(),
-            views: 0,
-        },
+    const payload: Partial<Ddoc> = {
+        domainId,
+        content,
+        owner,
+        parentType,
+        parentId,
+        title,
+        ip,
+        nReply: 0,
+        highlight,
+        pin,
+        updateAt: new Date(),
+        views: 0,
+    };
+    await bus.serial('discussion/before-add', payload);
+    const res = await document.add(
+        payload.domainId, payload.content, payload.owner, document.TYPE_DISCUSSION,
+        null, payload.parentType, payload.parentId, omit(payload, ['domainId', 'content', 'owner', 'parentType', 'parentId']),
     );
+    payload.docId = res;
+    await bus.emit('discussion/add', payload);
+    return payload.docId;
 }
 
 // FIXME typings doesn't work
diff --git a/packages/hydrooj/src/service/bus.ts b/packages/hydrooj/src/service/bus.ts
index 863e20e44..b51e08c8a 100644
--- a/packages/hydrooj/src/service/bus.ts
+++ b/packages/hydrooj/src/service/bus.ts
@@ -9,7 +9,7 @@ import { Logger } from '../logger';
 import type {
     Mdoc, Pdoc, Rdoc, TrainingDoc, User,
 } from '../interface';
-import type { DomainDoc } from '../loader';
+import type { Ddoc, DomainDoc } from '../loader';
 import type { DocType } from '../model/document';
 import type { ProblemSolutionHandler } from '../handler/problem';
 import type { UserRegisterHandler } from '../handler/user';
@@ -70,11 +70,8 @@ export interface EventMap extends Record<string, any> {
     'handler/finish/UserRegister': (thisArg: UserRegisterHandler) => VoidReturn
     'handler/solution/get': (thisArg: ProblemSolutionHandler) => VoidReturn
 
-    'discussion/before-add': (
-        domainId: string, parentType: number, parentId: ObjectID | number | string,
-        owner: number, title: string, content: string,
-        ip: string | null, highlight: boolean, pin: boolean
-    ) => VoidReturn
+    'discussion/before-add': (payload: Partial<Ddoc>) => VoidReturn
+    'discussion/add': (payload: Partial<Ddoc>) => VoidReturn
 
     'problem/before-add': (doc: Partial<Pdoc>) => VoidReturn
     'problem/add': (doc: Partial<Pdoc>, docId: number) => VoidReturn
diff --git a/packages/hydrooj/src/service/server.ts b/packages/hydrooj/src/service/server.ts
index 36b5e05aa..dd46f37cc 100644
--- a/packages/hydrooj/src/service/server.ts
+++ b/packages/hydrooj/src/service/server.ts
@@ -30,6 +30,7 @@ import {
     NotFoundError, HydroError,
 } from '../error';
 import * as misc from '../lib/misc';
+import { isContent, isName, isTitle } from '../lib/validator';
 import user from '../model/user';
 import domain from '../model/domain';
 import * as system from '../model/system';
@@ -57,6 +58,9 @@ interface ParamOption {
 type Type = [Converter, Validator, boolean?];
 
 export interface Types {
+    Content: Type,
+    Name: Type,
+    Title: Type,
     String: Type,
     Int: Type,
     UnsignedInt: Type,
@@ -73,6 +77,9 @@ export interface Types {
 }
 
 export const Types: Types = {
+    Content: [(v) => v.toString(), isContent],
+    Name: [(v) => v.toString(), isName],
+    Title: [(v) => v.toString(), isTitle],
     String: [(v) => v.toString(), null],
     Int: [(v) => parseInt(v, 10), (v) => isSafeInteger(parseInt(v, 10))],
     UnsignedInt: [(v) => parseInt(v, 10), (v) => parseInt(v, 10) >= 0],