I have a JavaScript application which is running in Node.js environment and communicates to its clients ( also in JavaScript ) using a ZeroMQ. The messages come on the server in JSON format.
The application code throws it out
Node.js SyntaxError: Unexpected token in JSON at position 0
when it is parsed using JSON.parse(). I'm unable to figure out the issue. I've verified the JSON using http://jsonlint.com
Any help with JSON.parse() is welcome.
Edited:01/10/17, 15:33
Here are the client and server JavaScript code files. You'll need to create the .js files, can't post such a big code.
The JSON data file is also provided.
You'll need to launch the server.js and client.js and then the server console will print out the exception for unrecognized character.
https://www.4shared.com/folder/6VFJqrgU/javascript.html
Stackoverflow imposes link posting restrictions so had to post one link with all the files.
Just for info, I'm a C++ programmer, so don't bother about the code formatting or style of programming. I had to do it for a project need.
Edit 02/10/17, 11:50: Well it turns out that it is the JSON.parse() method which is unable to parse the json. But, I added a .trim() call to the args[1].toString() and the error has moved downstream. Unexpected token o in JSON at position 10. I don't understand what is wrong!!
Edit 04/10/17: Here is the minimal code.
var fs = require('fs');
try
{
var event = fs.readFileSync('demoReport.json', 'utf8');
console.log(event);
var eventObj = JSON.parse(event);
var reportName = event["ReportName"];
var reportData = event["ReportData"];
console.log(reportData);
}
catch(error)
{
console.log("JSON parsing failed: " + error);
}
This is the json:
{"EventName":"ReportGenEvent","TemplateFileNameLocation":"File location","ReportFormat":".pdf","ReportName":"TestReport","ReportLocation":"report location","Locale":"French","ReportData":{"dateTime":"2017-09-29T00:05:22.824Z","streamName":"","measurementTime":"2017-04-01T01:13:25.000Z","durationSeconds":0.0,"outOfBand":false,"notFinal":false,"newMeasurement":false,"savedFileName":"","measurementType":"Unknown","analysisElapsedSeconds":1.3462,"analysisElapsedCPUSecs":0.0624004,"geometryID":"GEOM","geometryDescription":"","measurementUUID":"6060c80f-007c-4992-88f8-55e2200d99b7","backgroundUUID":"","measurementWorkflowID":"Measurement","instrumentProperties":{"classCode":8,"description":"","manufacturer":"","model":"","properties":"locationName=Home latitude=25 longitude=20 elevation=30","serialNumber":"product/1","versionInformation":"=V1.0"}}}
Thanks.
Related
Preamble
To start off, I'm not a developer; I'm just an analyst / product owner with time on their hands. While my team's actual developers have been busy finishing off projects before year-end I've been attempting to put together a very basic API server in Node.js for something we will look at next year.
I used Swagger to build an API spec and then used the Swagger code generator to get a basic Node.js server. The full code is near the bottom of this question.
The Problem
I'm coming across an issue when writing out to a log file using the fs module. I know that the ENOENT error is usually down to just specifying a path incorrectly, but the behaviour doesn't occur when I comment out the Swagger portion of the automatically generated code. (I took the logging code directly out of another tool I built in Node.js, so I'm fairly confident in that portion at least...)
When executing npm start, a few debugging items write to the console:
"Node Server Starting......
Current Directory:/mnt/c/Users/USER/Repositories/PROJECT/api
Trying to log data now!
Mock mode: disabled
PostgreSQL Pool created successfully
Your server is listening on port 3100 (http://localhost:3100)
Swagger-ui is available on http://localhost:3100/docs"
but then fs throws an ENOENT error:
events.js:174
throw er; // Unhandled 'error' event
^
Error: ENOENT: no such file or directory, open '../logs/logEvents2021-12-24.log'
Emitted 'error' event at:
at lazyFs.open (internal/fs/streams.js:277:12)
at FSReqWrap.args [as oncomplete] (fs.js:140:20)
Investigating
Now normally, from what I understand, this would just mean I've got the paths wrong. However, the file has actually been created and the first line of the log file has been written just fine
My next thought was that I must've set the fs flags incorrectly, but it was set to 'a' for append:
var logsFile = fs.createWriteStream(__logdir+"/logEvents"+dateNow()+'.log',{flags: 'a'},(err) =>{
console.error('Could not write new Log File to location: %s \nWith error description: %s',__logdir, err);
});
Removing Swagger Code
Now here's the weird bit: if I remove the Swagger code, the log files write out just fine and I don't get the fs exception!
This is the specific Swagger code:
// swaggerRouter configuration
var options = {
routing: {
controllers: path.join(__dirname, './controllers')
},
};
var expressAppConfig = oas3Tools.expressAppConfig(path.join(__dirname, '/api/openapi.yaml'), options);
var app = expressAppConfig.getApp();
// Initialize the Swagger middleware
http.createServer(app).listen(serverPort, function () {
console.info('Your server is listening on port %d (http://localhost:%d)', serverPort, serverPort);
console.info('Swagger-ui is available on http://localhost:%d/docs', serverPort);
}).on('error',console.error);
When I comment out this code, the log file writes out just fine.
The only thing I can think that might be happening is that somehow Swagger is modifying (?) the app's working directory so that fs no longer finds the same file?
Full Code
'use strict';
var path = require('path');
var fs = require('fs');
var http = require('http');
var oas3Tools = require('oas3-tools');
var serverPort = 3100;
// I am specifically tried using path.join that I found when investigating this issue, and referencing the app path, but to no avail
const __logdir = path.join(__dirname,'./logs');
//These are date and time functions I use to add timestamps to the logs
function dateNow(){
var dateNow = new Date().toISOString().slice(0,10).toString();
return dateNow
}
function rightNow(){
var timeNow = new Date().toTimeString().slice(0,8).toString();
return "["+timeNow+"] "
};
console.info("Node Server Starting......");
console.info("Current Directory: " + __dirname)
// Here I create the WriteStreams
var logsFile = fs.createWriteStream(__logdir+"/logEvents"+dateNow()+'.log',{flags: 'a'},(err) =>{
console.error('Could not write new Log File to location: %s \nWith error description: %s',__logdir, err);
});
var errorsFile = fs.createWriteStream(__logdir+"/errorEvents"+dateNow()+'.log',{flags: 'a'},(err) =>{
console.error('Could not write new Error Log File to location: %s \nWith error description: %s',__logdir, err);
});
// And create an additional console to write data out:
const Console = require('console').Console;
var logOut = new Console(logsFile,errorsFile);
console.info("Trying to log data now!") // Debugging logging
logOut.log("========== Server Startup Initiated ==========");
logOut.log(rightNow() + "Server Directory: "+ __dirname);
logOut.log(rightNow() + "Logs directory: "+__logdir);
// Here is the Swagger portion that seems to create the behaviour.
// It is unedited from the Swagger Code-Gen tool
// swaggerRouter configuration
var options = {
routing: {
controllers: path.join(__dirname, './controllers')
},
};
var expressAppConfig = oas3Tools.expressAppConfig(path.join(__dirname, '/api/openapi.yaml'), options);
var app = expressAppConfig.getApp();
// Initialize the Swagger middleware
http.createServer(app).listen(serverPort, function () {
console.info('Your server is listening on port %d (http://localhost:%d)', serverPort, serverPort);
console.info('Swagger-ui is available on http://localhost:%d/docs', serverPort);
}).on('error',console.error);
In case it helps, this is the project's file structure . I am running this project within a WSL instance in VSCode on Windows, same as I have with other projects using fs.
Is anyone able to help me understand why fs can write the first log line but then break once the Swagger code gets going? Have I done something incredibly stupid?
Appreciate the help, thanks!
Edit: Tried to fix broken images.
Found the problem with some help from a friend. The issue boiled down to a lack of understanding of how the Swagger module works in the background, so this will likely be eye-rollingly obvious to most, but keeping this post around in case anyone else comes across this down the line.
So it seems that as part of the Swagger initialisation, any scripts within the utils folder will also be executed. I would not have picked up on this if it wasn't pointed out to me that in the middle of the console output there was a reference to some PostgreSQL code, even though I had taken all reference to it out of the main index.js file.
That's when I realised that the error wasn't actually being generated from the code posted above: it was being thrown from to that folder.
So I guess the answer is don't add stuff to the utils folder, but if you do, always add a bunch of console logging...
I am getting an error that says SyntaxError: Unexpected token a in JSON at position 0
and I cannot find any information on what "a" means. I know that the JSON is not undefined.
Can anyone help me understand what is causing this error?
Here is the code block that is causing the error:
let db_creds = await getDBCredentials();
console.log(db_creds)
const pool = new Pool(JSON.parse(db_creds['SecretString']));
console.log(pool)
Unexpected Token < in JSON at Position 0. From time to time when working with JSON data, you might stumble into errors regarding JSON formatting. For instance, if you try to parse a malformed JSON with the JSON. ... json() method on the fetch object, it can result in a JavaScript exception being thrown.
What Is JSON and How to Handle an “Unexpected Token” Error
Well for me it was because the port was already in use and it must be sending HTML, you can try killing the port by running the below command in cmd(admin mode)
taskkill /F /IM node.exe
When I run my coffeescript test application I get this error"
2018-12-06 02:19:24,681 <NodeTest> [ERROR] [MainThread] node_test.run - NodeJS test for Node v7.9.0 did not pass. Exit status: 1
Std Out:
Std Error: /opt/node_js/conf.js:25
osVersion: 'MyOS 1.10.1.21
^^^^^^^^^^^^^^^^^
SyntaxError: Invalid or unexpected token
This is the contents of conf.js:
const require('https');
module.exports = {
// Endpoint
endpoint: 'https://123.456.789.876',
// creds
access: 'accessblablabla',
secret: 'secret blablabla',
// Other options
s3BucketEndpoint: false,
s3ForcePathStyle: true,
httpOptions: {
agent: new https.Agent({ca: '-----BEGIN CERTIFICATE-----'})
},
// OS version
myOsVersion: 'MyOS 1.10.1.21'
}
I can't understand why myOsVersion: '%s is any different compared with anything else in the file. Can anybody spot what I'm doing wrong?
I do not use MacOS at all but from my view, I think you should declare:
const https = require('https');
At the top of your code, because I see you use the instance of this (the new keyword). Hope this can help you a bit!
It turns out the problem was the space in the string.
As with #phix's comment, if I manually create the file there is no issue. I have a Python application which generates it. Perhaps it's including some hidden character or something.
Anyway, I only need the version number from the string so edited my Python code to look like this:
version = std_out.split()[1]
I'm working on a Python API to handle REST calls to MongoDB. The API is based on Kule (and thus includes Bottle and PyMongo modules). The front-end is built using node.js. I have been developing and testing on localhost with the API, front-end, and MongoDB on different ports.
I have set up the API and have been trying to get CRUD requests to work. I can get these to work from a Python script as well as from Javascript running on Apache server. However, when I add the same code to the front-end, GET works, but POST fails with a 500 error.
This POST code works on the Apache server:
var myrequest=new XMLHttpRequest();
myrequest.onreadystatechange=function(){
if (myrequest.readyState==4){
if (myrequest.status==201){
alert(myrequest.responseText);
} else{
alert("An error has occured making the request");
}
}
}
myrequest.open("POST", "http://localhost:8080/items", true);
myrequest.setRequestHeader("Content-type", "application/json;charset=UTF-8");
myrequest.send(JSON.stringify({'name' : 'Name', 'description' : 'Description'}));
When I add this to the front-end, I get the following traceback from Kule:
Traceback (most recent call last):
File "C:\Python27\lib\site-packages\bottle.py", line 764, in _handle
return route.call(**args)
File "C:\Python27\lib\site-packages\bottle.py", line 1625, in wrapper
rv = callback(*a, **ka)
File "C:\Python27\lib\site-packages\bottle.py", line 1575, in wrapper
rv = callback(*a, **ka)
File "C:\Python27\lib\site-packages\kule\kule.py", line 64, in post_list
inserted = collection.insert(request.json)
File "C:\Python27\lib\site-packages\pymongo\collection.py", line 351, in insert
docs = [self.__database._fix_incoming(doc, self) for doc in docs]
TypeError: 'NoneType' object is not iterable
127.0.0.1 - - [24/Jun/2014 07:53:40] "POST /scenarios HTTP/1.1" 500 50
So, what am I doing wrong? Why does the Javascript break in node.js? I have GET working, but POST fails. Why?
Thanks!
I found my error.
myrequest.setRequestHeader("Content-type", "application/json;charset=UTF-8");
"Content-type" should be "Content-Type" with an upercase "T".
Silly mistake. Left as a note to others.
I need to use LOAD DATA LOCAL INFILE using mysql-libmysqlclient in node. However I get an error
[Error: Query error #1148: The used command is not allowed with this MySQL version]
This does not happen running the same command from sequel pro so the issue is most likely with the connection used by mysql-libmysqlclient.
Anoyone know what parameters to send to mysql-libmysqlclient in order to fix this?
initializing connection:
secrets = stuff
mysql_db = mysql.createConnectionQueuedSync()
mysql_db.initSync()
mysql_db.realConnectSync secrets.host, secrets.user, secrets.password, secrets.database
mysql_db.connectError
module.exports = exports = mysql_db
Sending query:
mysql_db = require('./config/mysql_db')
sql_insert_into = "LOAD DATA local INFILE 'file_to_send.txt'
into table #{table.name}
FIELDS TERMINATED BY ';'
LINES TERMINATED by '\\n'
"
mysql_db.query sql_insert_into, (err, answer)->
console.log "sent " + sql_insert_into
The error I get:
[Error: Query error #1148: The used command is not allowed with this MySQL version]
Minor note: I program in coffee script but this shouldn't change anything
If LOAD DATA LOCAL is disabled, either in the server or the client, a client that attempts to issue such a statement receives the following error message:
ERROR 1148: The used command is not allowed with this MySQL version
You can refer MySql website link below for how to enable:
https://dev.mysql.com/doc/refman/5.5/en/load-data-local.html