I am using bluebird npm,I am getting the above error
I am calling three different function & doing some database operation, but I am getting this error.
If I tried with two functions, it is working but with three function it is throwing error, TypeError: Cannot read property 'call' of null.
If you go to bluebird/js/release/using.js and comment the line no 39 ;
If I comment this line, then this issue is not coming & all is working fine.
If you want more info please Click Here
This is main.js
var myModule = require('../lib/myModule');
var sync = require('deasync');
var id = 90;
var moduleObj = new moduleEntity(id);
console.log(moduleObj);
var id = 90;
var moduleObj = new moduleEntity(id);
console.log(moduleObj);
var id = 90;
var moduleObj = new moduleEntity(id);
console.log(moduleObj);
In MyModule.js
var deasync = require('deasync');
var dbEntity = require('../db/dbEntity');
module.exports = function (id) {
var outputEntity;
dbEntity(id, function(data){
outputEntity = data
});
while(outputEntity === undefined) { deasync.runLoopOnce();};
return outputEntity;
};
In dbEntery.js
var Promise = require("bluebird");
var getConnection = require('./dbcon');
module.exports = function (id,cb) {
var sql_getRecords = SELECT * from tanle_name;
Promise.using(getConnection, function (conn) {
return conn.query(sql_getRecords).then(function(data){
cb(data[0]);
})
});
};
Here is error stack trace
TypeError: Cannot read property 'call' of null
at FunctionDisposer.doDispose (/home/user/Projects/project_name/node_modules/bluebird/js/release/using.js:98:18)
at FunctionDisposer.Disposer.tryDispose (/home/user/Projects/project_name/node_modules/bluebird/js/release/using.js:78:20)
at iterator (/home/user/Projects/project_name/node_modules/bluebird/js/release/using.js:36:53)
at dispose (/home/user/Projects/project_name/node_modules/bluebird/js/release/using.js:48:9)
at /home/user/Projects/project_name/node_modules/bluebird/js/release/using.js:194:20
at PassThroughHandlerContext.finallyHandler (/home/user/Projects/project_name/node_modules/bluebird/js/release/finally.js:55:23)
at PassThroughHandlerContext.tryCatcher (/home/user/Projects/project_name/node_modules/bluebird/js/release/util.js:16:23)
at Promise._settlePromiseFromHandler (/home/user/Projects/project_name/node_modules/bluebird/js/release/promise.js:510:31)
at Promise._settlePromise (/home/user/Projects/project_name/node_modules/bluebird/js/release/promise.js:567:18)
at Promise._settlePromise0 (/home/user/Projects/project_name/node_modules/bluebird/js/release/promise.js:612:10)
at Promise._settlePromises (/home/user/Projects/project_name/node_modules/bluebird/js/release/promise.js:687:18)
at Async._drainQueue (/home/user/Projects/project_name/node_modules/bluebird/js/release/async.js:133:16)
at Async._drainQueues (/home/user/Projects/project_name/node_modules/bluebird/js/release/async.js:143:10)
at Immediate.Async.drainQueues (/home/user/Projects/project_name/node_modules/bluebird/js/release/async.js:17:14)
at runCallback (timers.js:651:20)
at tryOnImmediate (timers.js:624:5)
Bluebird version -- 3.5
Node Version -- v7.6.0
You provided no code examples so it's hard to give you any detailed answer but here are some things that you have to keep in mind when you get error like this.
TypeError: Cannot read property 'call' of null means that some code (also impossible to tell you which code because you didn't provide an example and full error stack trace) tries to bind some function to some this object and arguments using Function.prototype.call() - see:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/call
but instead of the function it got null.
Now you need to follow the stack trace and see which code is trying to call the function and where the null originated to fix your problem.
Note that it is null and not undefined so it must have been provided explicitly instead of just being a missing argument to a function call or a missing property on an object. This is an important hint that should let you diagnose the problem much easier.
Related
I try to use fs on a discordjs bot (v13) but I have a strange error.
I have literally 3 lines between the moment when I can console.log my fs object and the error :
// Get FS
const fs = require('fs');
// Recieves commands
client.on('interactionCreate', async interaction => {
console.log(fs); // OK
switch(interaction.commandName) {
// Get list of all maps for this server
case 'maps':
const pngfiles = fs.readdirSync('./maps/').filter(f => f.endsWith(".png")); // NOT OK !!!!!!!
response = "**List all maps available in this server:**\n\n\n"+pngfiles.join("\n")+"\n";
break;
}
});
And the error :
/home/chenille33/DPW/app.js:156
const pngfiles = fs.readdirSync('./maps/').filter(f => f.endsWith(".png"));
^
ReferenceError: Cannot access 'fs' before initialization
at Client.<anonymous> (/home/chenille33/DPW/app.js:156:34)
at Client.emit (node:events:527:28)
at InteractionCreateAction.handle (/home/chenille33/DPW/node_modules/discord.js/src/client/actions/InteractionCreate.js:74:12)
at module.exports [as INTERACTION_CREATE] (/home/chenille33/DPW/node_modules/discord.js/src/client/websocket/handlers/INTERACTION_CREATE.js:4:36)
at WebSocketManager.handlePacket (/home/chenille33/DPW/node_modules/discord.js/src/client/websocket/WebSocketManager.js:351:31)
at WebSocketShard.onPacket (/home/chenille33/DPW/node_modules/discord.js/src/client/websocket/WebSocketShard.js:444:22)
at WebSocketShard.onMessage (/home/chenille33/DPW/node_modules/discord.js/src/client/websocket/WebSocketShard.js:301:10)
at WebSocket.onMessage (/home/chenille33/DPW/node_modules/ws/lib/event-target.js:199:18)
at WebSocket.emit (node:events:527:28)
at Receiver.receiverOnMessage (/home/chenille33/DPW/node_modules/ws/lib/websocket.js:1137:20)
Node.js v18.0.0
What I've missed ? Thanks in advance.
That specific error implies that somewhere else in your function scope (not shown in the code in your question), you likely have const fs = ... or let fs = ... and are thus attempting to redefine fs in this function scope which is hiding the higher scoped fs.
The error means that you're trying to use the variable fs BEFORE its const fs = ... or let fs = ... definition in this scope have been executed. Unlike with var (where definitions are internally hoisted), you can't use a variable before its declaration with let or const.
Based on the bit of code we can see, I would guess you're doing this in one of the other case handlers in your switch statement or somewhere else in the function containing this switch statement. When you don't use braces to define a new scope for each case handler, then those are ALL within the same scope and all const or let definitions there can interfere with each other.
So, look for a redefinition of fs somewhere else in this function. And, if that isn't obvious to you, then post all the code for this function where the error occurs.
Here's a stand-alone example that reproduces that exact same error. This is the kind of thing you should be looking for:
let greeting = "hi";
const fs = require('fs');
switch (greeting) {
case "hi":
fs.readFileSync("temp.js");
console.log("got hi");
break;
case "goodbye":
const fs = require('fs'); // this redefinition causes the error
// when the "hi" case executes
console.log("got goodbye");
break;
default:
console.log("didn't match");
break;
}
// or a redefinition of fs here (in the same function) would also cause the error
When you run this, it gives this error:
ReferenceError: Cannot access 'fs' before initialization
Or, similarly, if you were defining fs somewhere else in the same function containing the switch statement, but after the switch statement. That would also cause the same problem.
Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 2 years ago.
Improve this question
I have no prior knowledge about backend related codes and all so I decided to start recent to learn a few things gradually so I decided to follow a tutorial and now I'm stuck with an error I've researched but cannot still fix.
I have this
const postsSchema = require('./posts')
const resolvers = [
postsSchema.resolvers
]
const typeDefs = [
postsSchema.schema
]
module.exports = {
resolvers,
typeDefs
}
const trendingPosts = require('./mocks/trending')
const featuredPosts = require('./mocks/featured')
const fs = require('fs')
const path = require('path')
module.exports = {
resolvers: {
Query: {
trendingPosts: () => trendingPosts,
featuredPosts: () => featuredPosts,
recentPosts: () => [
...trendingPosts,
...featuredPosts,
...featuredPosts
]
}
},
schema: fs.readFileSync(
path.resolve(
__dirname,
'./posts-schema.graphql'
)
).toString
}
This is my GraphQl
type Query {
trendingPosts: [Post]!
featuredPosts: [Post]!
recentPosts: [Post]!
}
type Post {
id: Int,
title: String
date: String
categories: [String]
author: String
description: String
image: String
}
I'm quite sure I followed the whole process in the tutorial but when I run node app, I get this error in the terminal
buffer.js:778
return this.utf8Slice(0, this.length);
^
TypeError: Cannot read property 'utf8Slice' of undefined
at toString (buffer.js:778:17)
at C:\Users\Natey\Desktop\Code Related\my-app\graphql\node_modules\#graphql-tools\schema\index.cjs.js:195:65
at Array.forEach (<anonymous>)
at concatenateTypeDefs (C:\Users\Natey\Desktop\Code Related\my-app\graphql\node_modules\#graphql-tools\schema\index.cjs.js:191:24)
at buildDocumentFromTypeDefinitions (C:\Users\Natey\Desktop\Code Related\my-app\graphql\node_modules\#graphql-tools\schema\index.cjs.js:231:46)
at buildSchemaFromTypeDefinitions (C:\Users\Natey\Desktop\Code Related\my-app\graphql\node_modules\#graphql-tools\schema\index.cjs.js:213:22)
at makeExecutableSchema (C:\Users\Natey\Desktop\Code Related\my-app\graphql\node_modules\#graphql-tools\schema\index.cjs.js:811:32)
at Object.<anonymous> (C:\Users\Natey\Desktop\Code Related\my-app\graphql\app.js:8:13)
at Module._compile (internal/modules/cjs/loader.js:1063:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
I need help please, I'll really appreciate it.
As #pzaenger pointed out .toString should be .toString()
Edit:
The key here is to learn to read your stack traces.
buffer.js:778 // This is a node module
return this.utf8Slice(0, this.length);
^
TypeError: Cannot read property 'utf8Slice' of undefined // This is sort of helpful, it's telling use something is trying to access a function utf8Slice of undefined
at toString (buffer.js:778:17) // buffer.js is trying to access utf8Slice on a this object at `toString`
// So now we know a buffer is trying to call utf8Slice on an undefined `this`
// at `toString`. Taking a quick look at your code we see fs.readFileSync(...)
// which gives us a buffer back and then `fs.readFileSync(...).toString`
// experince tells us that toString is a function not a property
I have been using pdf-merger-js to merge PDF files for a while now. I have used it with PDF files I have generated from HTML files and with PDF files I did not create.
Then I started getting the error:
Uncaught TypeError: Cannot read property 'compressed' of undefined
and the merger would fail. I tried different versions of node with the same results. The version that has been working is node v12.19.1.
/* /path/to/project/mpdf.js */
const PDFMerger = require('pdf-merger-js');
const path = require('path');
(async () => {
try {
const pdfs = ['pdf1.pdf','pdf2.pdf','pdf3.pdf','pdf4.pdf','pdf5.pdf'];
const merger = new PDFMerger();
pdfs.map(f => path.resolve(__dirname, "subfolder", f)
.forEach(pdf => merger.add(pdf));
//^^^Error occurs on this line
await merger.save('all-merged.pdf');
} catch( err ) {
console.log( err );
}
})();
Has any of you worked with pdf-merger-js and, have you encountered the above error? If so, how did you resolve the error?
Stack Trace
TypeError: Cannot read property 'compressed' of undefined
at parseObject (/path/to/project/node_modules/pdfjs/lib/object/reference.js:81:15)
at PDFReference.get [as object] (/path/to/project/node_modules/pdfjs/lib/object/reference.js:15:17)
at new ExternalDocument (/path/to/project/node_modules/pdfjs/lib/external.js:20:42)
at PDFMerger._addEntireDocument (/path/to/project/node_modules/pdf-merger-js/index.js:29:15)
at PDFMerger.add (/path/to/project/node_modules/pdf-merger-js/index.js:11:12)
at /path/to/project/app3.js:10:34
at Array.forEach (<anonymous>)
at /path/to/project/app3.js:10:12
at processTicksAndRejections (internal/process/task_queues.js:97:5)
Update
I have encountered another set of PDF files that are throwing a different error on the same line:
TypeError: Cannot read property 'object' of undefined
at new ExternalDocument (/path/to/project/node_modules/pdfjs/lib/external.js:20:42)
at PDFMerger._addEntireDocument (/path/to/project/node_modules/pdf-merger-js/index.js:29:15)
at PDFMerger.add (/path/to/project/node_modules/pdf-merger-js/index.js:11:12)
at /path/to/project/app3.js:10:34
at Array.forEach (<anonymous>)
at /path/to/project/app3.js:10:12
at processTicksAndRejections (internal/process/task_queues.js:97:5)
I got the same error whenever I used compressed PDFs for merging. Seems to be a bug in the underlying pdfjs library according to a Github issue in the pdf-merger-js repository.
Not the kind of answer I was looking for ....
If you flatten the files prior to merging them then the merging works fine. This seems to resolve the two errors I encountered.
I am using pdf-flatten just before merging as follows:
const fsp = require('fs').promises;
const flattener = require('pdf-flatten');
//....
const pdfs = ['pdf1.pdf','pdf2.pdf','pdf3.pdf','pdf4.pdf','pdf5.pdf'];
for(pdf of pdfs) {
const pdfB = await fsp.readFile(path.resolve(__dirname,"subfolder", pdf));
const pdfFlat = await flattener.flatten(pdfB, {density: 300});
await fsp.writeFile(path.resolve(__dirname,"subfolder", `flattened_${pdf}`), pdfFlat);
}
//....merge the flattened files:
//.... pdfs.map(p => `flattened_${p}`).....
Mongoose emits a stack trace for a cast error. I know how to prevent the Mongoose error - please do not answer how to prevent the error.
How can I stop Mongoose emitting stack trace errors in production?
Error: Argument passed in must be a single String of 12 bytes or a
string of 24 hex characters at new ObjectID
(c:\proj\fboapp\node_modules\mongoose\node_modules\bson\lib\bson\objectid.js:38:11)
at c:\proj\fboapp\routes\user\no_auth_user_api_routes.js:135:27 at
Layer.handle [as handle_request]
(c:\proj\fboapp\node_modules\express\lib\router\layer.js:95:5) at
next (c:\proj\fboapp\node_modules\express\lib\router\route.js:131:13)
at Route.dispatch
(c:\proj\fboapp\node_modules\express\lib\router\route.js:112:3) at
Layer.handle [as handle_request]
(c:\proj\fboapp\node_modules\express\lib\router\layer.js:95:5) at
c:\proj\fboapp\node_modules\express\lib\router\index.js:277:22 at
Function.process_params
(c:\proj\fboapp\node_modules\express\lib\router\index.js:330:12) at
next (c:\proj\fboapp\node_modules\express\lib\router\index.js:271:10)
at Function.handle
(c:\proj\fboapp\node_modules\express\lib\router\index.js:176:3) at
router (c:\proj\fboapp\node_modules\express\lib\router\index.js:46:12)
at Layer.handle [as handle_request]
(c:\proj\fboapp\node_modules\express\lib\router\layer.js:95:5) at
trim_prefix
(c:\proj\fboapp\node_modules\express\lib\router\index.js:312:13) at
c:\proj\fboapp\node_modules\express\lib\router\index.js:280:7 at
Function.process_params
(c:\proj\fboapp\node_modules\express\lib\router\index.js:330:12) at
next (c:\proj\fboapp\node_modules\express\lib\router\index.js:271:10)
Nodejs v0.12.3
Mongoose v4.4.3
Generally speaking, add try-catch block in the codes could be correct way to do it.
Here are my test codes without try-catch block in codes, then prevent stack trace. Refer to this module mongoose disable stack trace, also add some new errors are added into mongoose, and set Error.stackTraceLimit to 0 will disable stack trace collection.
index.js
const captureStackTrace = Error.captureStackTrace;
const CastError = module.parent.require('mongoose/lib/error/cast');
const VersionError = module.parent.require('mongoose/lib/error/version');
const ValidatorError = module.parent.require('mongoose/lib/error/validator');
const ValidationError = module.parent.require('mongoose/lib/error/validation');
const OverwriteModelError = module.parent.require('mongoose/lib/error/overwriteModel');
const MissingSchemaError = module.parent.require('mongoose/lib/error/missingSchema');
const DivergentArrayError = module.parent.require('mongoose/lib/error/divergentArray');
Error.captureStackTrace = function( that, params) {
if(that instanceof CastError ||
that instanceof VersionError ||
that instanceof ValidatorError ||
that instanceof ValidationError ||
that instanceof OverwriteModelError ||
that instanceof MissingSchemaError ||
that instanceof DivergentArrayError) {
Error.stackTraceLimit = 0;
} else if (typeof that !== 'undefined'){
captureStackTrace.apply(Error, arguments);
}
}
Error.captureStackTrace(new VersionError);
app.js
require('mongoose-disable-stack-trace');
var f = Foo({_id: new ObjectId('adss112'), key: '123'}); // invalid ObjectId
Output:
Error: Argument passed in must be a single String of 12 bytes or a string of 24
hex characters
c:\share\node\node_modules\mongoose\node_modules\mongodb\lib\server.js:283
process.nextTick(function() { throw err; }) ^
Error: Argument passed in must be a single String of 12 bytes or a string of 24
hex characters
I was confused about why errors were being rendered to the browser without an error handler, until I read the ExpressJS error handling documentation page.
Apparently there is a default error handler which is triggered when no error handler is specified.
Express comes with an in-built error handler, which takes care of any
errors that might be encountered in the app. This default
error-handling middleware function is added at the end of the
middleware function stack.
The best practice is to specify a custom error handler for production which does not output the stack trace to the browser. The default error handler always outputs the stack trace to the browser.
There is no need for try-catch blocks to route uncaught errors to the custom error handler, because Express will automatically route uncaught errors to the error handler. Also note: error handler middleware MUST specify all 4 arguments: err, req, res and next
An example of a custom error handler:
app.use(function(err, req, res, next) {
res.send('uncaught error in production');
});
I get the warning about not returning a created promise from Bluebird and I do not understand why and how I should rewrite my code.
(I have tried reading about the warning at Bluebird API page and the anti-pattern page as I suspect this is what I'm doing)
In my view.js file:
var express = require('express'),
router = express.Router(),
settings = myReq('config/settings'),
Sets = myReq('lib/Sets'),
log = myReq('lib/utils').getLogger('View');
router.get('/:setId/', function(req, res, next) {
var
setId = req.params.setId,
user = req.user,
set = new Sets(setId, user);
log.info('Got a request for set: ' + setId);
// The below line gives the warning mentioned
set.getSet().then(function(output) {
res.send(output);
}).error(function(e){
log.error(e.message, e.data);
res.send('An error occurred while handling set:' + e.message);
});
});
module.exports = router;
In my Sets.js file I have:
var
Promise = require('bluebird'),
OE = Promise.OperationalError,
settings = myReq('config/settings'),
UserData = myReq('lib/userData'),
log = myReq('lib/utils').getLogger('sets'),
errorToSend = false;
module.exports = function(setId, user) {
var
sets = myReq('lib/utils').getDb('sets');
return {
getSet : function() {
log.debug('Getting set')
return sets.findOneAsync({
setId:setId
}).then(function(set){
if ( set ) {
log.debug('got set from DB');
} else {
set = getStaticSet(setId);
if ( ! set ) {
throw new OE('Failed getting db records or static template for set: ' + setId );
}
log.debug('got static set');
}
log.debug('I am handling set')
if ( ! checkSet(set) ) {
var e = new OE('Failed checking set');
e.data = set;
throw e;
}
return {
view : getView(set),
logic : set.logic,
canEdit : true,
error : errorToSend
};
});
}
};
};
So the line in my view.js file with "set.getSet()" gives the warning about not returning the created promise. It seems like this script still does what I expect it to do, but I do not understand why I get the warning.
Stacktrace:
Warning: a promise was created in a handler but was not returned from it
at Object.getSet (C:\dev\infoscrn\lib\Sets.js:36:25)
at C:\dev\infoscrn\routes\view.js:39:20
at Layer.handle [as handle_request] (C:\dev\infoscrn\node_modules\express\lib\router\layer.js:82:5)
at next (C:\dev\infoscrn\node_modules\express\lib\router\route.js:110:13)
at Route.dispatch (C:\dev\infoscrn\node_modules\express\lib\router\route.js:91:3)
at Layer.handle [as handle_request] (C:\dev\infoscrn\node_modules\express\lib\router\layer.js:82:5)
at C:\dev\infoscrn\node_modules\express\lib\router\index.js:267:22
at param (C:\dev\infoscrn\node_modules\express\lib\router\index.js:340:14)
at param (C:\dev\infoscrn\node_modules\express\lib\router\index.js:356:14)
at Function.proto.process_params (C:\dev\infoscrn\node_modules\express\lib\router\index.js:400:3)
at next (C:\dev\infoscrn\node_modules\express\lib\router\index.js:261:10)
at Function.proto.handle (C:\dev\infoscrn\node_modules\express\lib\router\index.js:166:3)
at router (C:\dev\infoscrn\node_modules\express\lib\router\index.js:35:12)
at Layer.handle [as handle_request] (C:\dev\infoscrn\node_modules\express\lib\router\layer.js:82:5)
at trim_prefix (C:\dev\infoscrn\node_modules\express\lib\router\index.js:302:13)
at C:\dev\infoscrn\node_modules\express\lib\router\index.js:270:7
at Function.proto.process_params (C:\dev\infoscrn\node_modules\express\lib\router\index.js:321:12)
at next (C:\dev\infoscrn\node_modules\express\lib\router\index.js:261:10)
at C:\dev\infoscrn\node_modules\express\lib\router\index.js:603:15
at next (C:\dev\infoscrn\node_modules\express\lib\router\index.js:246:14)
First, try and update all your dependencies. There's been a recent version of Bluebird, which fixed an issue involving this warning.
Next, make sure you return from all your handlers.
Then, if you still get the warning (like I do) you can disable this specific warning. I chose to do so by setting BLUEBIRD_W_FORGOTTEN_RETURN=0 in my environment.
Don't disable warnings. They're there for a reason.
The typical pattern is that if your onfulfill or onreject handler causes a Promise to be constructed, it will return that Promise (or some chain derived from it) from the handler, so that the chain adopts the state of that Promise.
So Bluebird is keeping track of when it is running one of your handler functions, and also keeping track of when it's Promise constructor is called. If it determines that a Promise was created at any point while your handler is running (that includes anywhere down in the callstack), but that Promise was not returned from your handler, it issues this warning because it thinks you probably forgot to write the return statement.
So if you legitimately don't care about the Promise that was created inside the handler, all you have to do is explicitly return something from your handler. If you don't care about what is returned from your handler (i.e., if you don't care what value the Promise fulfills with), then simply return null. Whatever you return, the explicit return (specifically, a return value other than undefined) tells Bluebird that you think you know what you're doing, and it won't issue this warning.
Make sure that every place you have return statement which is the solution works for me.