diff --git a/src/route/contents.ts b/src/route/contents.ts
index cf06b82..6f6243f 100644
--- a/src/route/contents.ts
+++ b/src/route/contents.ts
@@ -7,9 +7,6 @@ import {sendError} from './error_handler';
 
 const ContentIDHandler = (controller: ContentAccessor) => async (ctx: Context,next: Next)=>{
     const num = Number.parseInt(ctx.params['num']);
-    if (num === NaN){
-        return await next();
-    }
     let content = await controller.findById(num,true);
     if (content == undefined){
         sendError(404,"content does not exist.");
@@ -21,9 +18,6 @@ const ContentIDHandler = (controller: ContentAccessor) => async (ctx: Context,ne
 };
 const ContentTagIDHandler = (controller: ContentAccessor) => async (ctx: Context,next: Next)=>{
     const num = Number.parseInt(ctx.params['num']);
-    if (num === NaN){
-        return await next();
-    }
     let content = await controller.findById(num,true);
     if (content == undefined){
         sendError(404,"content does not exist.");
@@ -73,9 +67,6 @@ const CreateContentHandler = (controller : ContentAccessor) => async (ctx: Conte
 const AddTagHandler = (controller: ContentAccessor)=>async (ctx: Context, next: Next)=>{
     let tag_name = ctx.params['tag'];
     const num = Number.parseInt(ctx.params['num']);
-    if (num === NaN){
-        return await next();
-    }
     if(typeof tag_name === undefined){
         sendError(400,"??? Unreachable");
     }
@@ -92,9 +83,6 @@ const AddTagHandler = (controller: ContentAccessor)=>async (ctx: Context, next:
 const DelTagHandler = (controller: ContentAccessor)=>async (ctx: Context, next: Next)=>{
     let tag_name = ctx.params['tag'];
     const num = Number.parseInt(ctx.params['num']);
-    if (num === NaN){
-        return await next();
-    }
     if(typeof tag_name === undefined){
         sendError(400,"?? Unreachable");
     }
@@ -110,9 +98,6 @@ const DelTagHandler = (controller: ContentAccessor)=>async (ctx: Context, next:
 }
 const DeleteContentHandler = (controller : ContentAccessor) => async (ctx: Context, next: Next) => {
     const num = Number.parseInt(ctx.params['num']);
-    if (num === NaN){
-        return await next();
-    }
     const r = await controller.del(num);
     ctx.body = {"ret":r};
     ctx.type = 'json';
@@ -120,12 +105,13 @@ const DeleteContentHandler = (controller : ContentAccessor) => async (ctx: Conte
 export const getContentRouter = (controller: ContentAccessor)=>{
     const ret = new Router();
     ret.get("/search",ContentQueryHandler(controller));
-    ret.get("/:num",ContentIDHandler(controller));
+    ret.get("/:num(\\d+)",ContentIDHandler(controller));
+    //ret.get("/:num(\\d+)/:content_type");
     ret.post("/",CreateContentHandler(controller));
-    ret.get("/:num/tags",ContentTagIDHandler(controller));
-    ret.post("/:num/tags/:tag",AddTagHandler(controller));
-    ret.del("/:num/tags/:tag",DelTagHandler(controller));
-    ret.del("/:num",DeleteContentHandler(controller));
+    ret.get("/:num(\\d+)/tags",ContentTagIDHandler(controller));
+    ret.post("/:num(\\d+)/tags/:tag",AddTagHandler(controller));
+    ret.del("/:num(\\d+)/tags/:tag",DelTagHandler(controller));
+    ret.del("/:num(\\d+)",DeleteContentHandler(controller));
     //ret.get("/");
     return ret;
 }