TypeError: Cannot read property 'length' of undefined

[devopsadmin-james]

Hi there,

i have tried to implement oauth2 using this repo.

Everything went well till run node application with below command

node app.js

But when we hit browser below command
http://127.0.0.1:3000/authorize?response_type=code&scope=email%20address&client_id=wHsY4YI6K7gn2bYhsgPv4HB8Sw9bZ0JV
(client_id=wHsY4YI6K7gn2bYhsgPv4HB8Sw9bZ0JV : generated while creating client application)

we get this error: TypeError: Cannot read property 'length' of undefined

i have even tried this url in browser as well

http://127.0.0.1:3000/authorize?response_type=code&scope=myemail@gmail.com&client_id=wHsY4YI6K7gn2bYhsgPv4HB8Sw9bZ0JV

gettting same error.

Check below stack-trace

osboxes@osboxes:~/kong-oauth2-hello-world$ node app.js 
PROVISION_KEY is xE4QYq1PiW6L5645Y9u52xiP5Qu3jLUR
SERVICE_HOST is mockbin.org
KONG_ADMIN is http://127.0.0.1:8001
KONG_API is https://127.0.0.1:8443
API_PATH is /mock
SCOPES is {   "email": "Grant permissions to read your email address",   "address": "Grant permissions to read your address information",   "phone": "Grant permissions to read your mobile phone number" }
Running at Port 3000
/home/osboxes/kong-oauth2-hello-world/app.js:70
      if (json_response.data.length == 1) {
                             ^

TypeError: Cannot read property 'length' of undefined
    at Request._callback (/home/osboxes/kong-oauth2-hello-world/app.js:70:30)
    at Request.self.callback (/home/osboxes/kong-oauth2-hello-world/node_modules/request/request.js:197:22)
    at emitTwo (events.js:126:13)
    at Request.emit (events.js:214:7)
    at Request.<anonymous> (/home/osboxes/kong-oauth2-hello-world/node_modules/request/request.js:1050:14)
    at emitOne (events.js:121:20)
    at Request.emit (events.js:211:7)
    at IncomingMessage.<anonymous> (/home/osboxes/kong-oauth2-hello-world/node_modules/request/request.js:996:12)
    at emitNone (events.js:111:20)
    at IncomingMessage.emit (events.js:208:7)

How to resolve this error

Thanks & regards

[kele1997]

I met the same issue.
To sovle this, you need to know two things:

1. this app will send request to kong admin api, but this request is not send from the app's ip, but your browser's ip, so make sure your browser can send request to kong admin api successfully.
2. maybe you use the lastest kong , and this app seems does't update in time. so you can modify it by your self.

before modify

kong-oauth2-hello-world/app.js

Lines 70 to 76 in 4ffe961

	if (json_response.data.length == 1) {
	application_name = json_response.data[0].name;
	}
	}
	callback(application_name);
	});
	}

after modify

   if (json_response.data.length == 1) { 
+        console.log(json_response); // print json_response, if json_response =='{"message":"not found"}', it seems your browser can't send request to kong admin api
+        application_name = json_response[name];
-        application_name = json_response.data[0].name; 
       } 
     } 
     callback(application_name); 
   }); 
 } 

[josepereira1]

you should check first if json_response.data is not undefined, before invoke length, without this, server can fail:
if (json_response.data && json_response.data.length == 1) { application_name = json_response.data[0].name; }