I'm having issues with writing to a socket (with http) from a sqlite (sqlite3) libary in Node.JS
https://gist.github.com/RyanCopley/6004c3ce372e060bbf18
Lines 68 to 75, I have 4 attempts to write. Outside of the db.each, everything works in any context. INSIDE of it, it crashes miserably. I'm not entirely sure why, but I feel like there is a conflict between the two libraries
BTW I already know concatenating the SQL statement is bad :3
This is because the callback function in db.each is called asynchronously. This means that line 79: res.end() will be called before res.write("Found row!");, triggering an error.
I think what you want to do is something like this:
db.serialize(function() {
that.res.write("["); // works
db.each("SELECT * FROM messages WHERE channel = '"+q.chan+"' AND id > "+q.since+" ORDER BY id", function(err, row) {
res.write("Found row!"); //does not work
that.res.write("Found row!"); //does not work
console.log("Found row!");
});
res.write("]");//works
});
Related
My issue was, that with the default GetOptions (omitting the parameter), a request like the following could load seconds if not minutes if the client is offline:
await docRef.get()...
If I check if the client is offline and in this case purposefully change the Source to Source.cache, I have performance that is at least as good, if not better, than if the client was online.
Source _source = Source.serverAndCache;
try {
final result = await InternetAddress.lookup('example.com');
if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
_source = Source.serverAndCache;
}
} on SocketException catch (_) {
_source = Source.cache;
}
and then use this variable in the following way:
docRef.get(GetOptions(source: _source))
.then(...
This code works perfectly for me now, but I am not sure, if there are any cases in which using the code like this could raise issues.
Also it seems like a lot of boilerplate code (I refactored it into a function so I can use it in any Database methods but still...)
If there are no issues with this, why wouldn't this be the Firebase default, since after trying the server for an unpredictably long time it switches to cache anyways.
I have been struggling to find a solution for this and it seems that i'm doing something in the wrong way due to my limited knowladge, so here is the breakdown of the problem:
public void RegisterNewUser()
{
FetchRegisterInputValues();
if (CheckRegisterDataIntegrity())
{
_auth.CreateUserWithEmailAndPasswordAsync(_email, _password).ContinueWith(task => {
if (task.IsCanceled) {
Debug.LogError("CreateUserWithEmailAndPasswordAsync was canceled.");
return;
}
if (task.IsFaulted)
{
HandleRegistrationErrors(task.Exception);
return;
}
// Firebase user has been created.
Firebase.Auth.FirebaseUser newUser = task.Result;
Debug.LogFormat("Firebase user created successfully: {0} ({1})",
newUser.DisplayName, newUser.UserId);
});
}
else if (!CheckRegisterDataIntegrity())
{
HandleRegistrationErrors(new AggregateException("passwords do not match"));
}
}
above is the Registration function that I got straight from Firebase docs, it's very straightforward
the FetchRegisterInputValues(); function gets the email and passwords, the CheckRegisterDataIntegrity() compares the password with the password conformation in the form, and finally HandleRegistrationErrors(task.Exception); is meant to fire a popup panel to show the error,
this is how HandleRegistrationErrors(task.Exception); looks
private void HandleRegistrationErrors(AggregateException errMsg)
{
print("its here from the errors method " + errMsg.Message);
registerErrorPopup.OpenNotification();
registerErrorPopup.description = errMsg.Message;
}
it's using a UI asset from the asset store, the .OpenNotification(); starts the animation and pops it up, and then im just showing the message.
Now, I got two problems, the first is when there is an error encountered by Firebase and the if (task.IsFaulted) Condition is true, the HandleRegistrationErrors function should be called, right?. well that's exactly what happens, except only the print("it's here from the errors method " + errMsg.Message); line gets called and the rest of the function does not execute, I thought at first that its a problem with asset, but I tried doing it manually (created a native UI with unity and used SetActive() method to start the popUp), but again only print method executed, I think its because of the
CreateUserWithEmailAndPasswordAsync is Asynchronous and I should handle errors accordingly, but I really don't know how to go about it and there is no documentation that I could find.
The second problem is how to get the correct Error Message because of the task.Exception.Message always returns me a "One or more errors occurred". while the task.Exception itself gives the right message but it's not formatted correctly.
The first question is the easiest. To update your code with the minimal amount of effort, just replace ContinueWith with ContinueWithOnMainThread will force logic onto the main thread. Also, you should avoid calling task.Result if task.Exception is non-null as it will just raise the exception (see the related documentation).
For the threading related stuff: I go into much more detail about threading with Firebase and Unity here and you can read about the ContinueWithOnMainThread extension here.
For your second issue, the issue you're running into is that task.Exception is an AggregateException. I typically just attach a debugger and inspect this when debugging (or let Crashlytics analyze it in the field), and my UI state is only concerned about success or failure. If you want to inspect the error, the documentation I linked for AggregateException recommends doing something like:
task.Exception.Handle((e) => Debug.LogError($"Failed because {e}"));
Although I would play with .Flatten() or .GetBaseException() to see if those are easier to deal with.
I hope this helps!
--Patrick
I have a fairly simple Meteor application.
I tried to send newsletter to about 3000 users in my list and things went wrong. A random set of users got multiple emails (between 41 to 1).
I shut the server down as soon I noticed this behavior. around 1300 emails were sent to 210 users. I am trying to figure out what happened and why.
Here is the code flow:
SendNow (client clode) --> SendNow (server method) --> populateQue (server function) --> processQue(server function) --> sendEmails (server method)
Client side code :
'click .sendNow': function(){
/* code that forms data object */
Meteor.call('sendNow',data);
}
Server code : server/method.js
Meteor.methods({
'sendNow' : function(data){
if(userWithPermission()){
var done = populateQue(data);
if(done)
processQue();
return {'method':'sendNow','status':'ok'}
},
'sendEmails': function(data){
this.unblock();
var result = Mandrill.messages('send', data);// using external library
SentEmails.insert(data);//Save sent emails in a collection
}
});
Function on server : server/utils.js
populateQue = function(data) {
/* code to get all users in to array */
MessageQue.remove();//Remove all documents from the Que
for (var i=0; i<users.length; i++) {
MessageQue.insert({userId: users[i]._id});
}
return true;
}
processQue = function(){
var messageQue = MessageQue.find({}).fetch();
for(i=0; i < messageQue.length; i++){
Meteor.call('sendEmails', data);
MessageQue.remove({_id: messageQue[i]._id});//Remove sent emails from the Que
}
}
My first hunch was MessageQue got messed up as I am removing items while processQue is using it but i was wrong. I am unable to simulate this behavior again after few tests
Test 1 : replaced Mandrill.message('send',data) with Meteor._sleepForMs(1000); - Only one email/person was seen in SentEmails collection.
Test 2 : Put Mandrill in Test mode (had to use different API key) and re ran the code with couple of log statements. - Only one email/person was seen in SentEMails and also in Mandrill's interface.
It's definitely not external library. its somewhere in my code or in the way I understood meteor to work.
Only one thing I noticed is an error occurred while accessing SentEmails collection through another view code. I have a view that displays SentEmails on the client with date as filter.
Here is the error :
Exception from sub sentEmailDocs id 9LTq6mMD4xNcre4YX Error:
Exception while polling query
{
"collectionName":"sent_emails",
"selector":{"date":{"$gt":"2015-07-09T05:00:00.000Z","$lt":"2015-07-11T05:00:00.000Z"}},
"options":{"transform":null,"sort":{"date":-1}}
}:
Runner error: Overflow sort stage buffered data usage of 33565660 bytes exceeds internal limit of 33554432 bytes
Is this the smoking gun? Would this have caused the random behavior?
I have put couple checks to prevent this from happening but I am puzzled on what might have caused and why? I will be happy to provide more information. Thanks in advance to who ever is willing to spend few mins on this.
Shot in the dark here, but the remove method takes an object, otherwise it doesn't do anything. MessageQue.remove() probably didn't clear the queue. You need MessageQue.remove({}). Test the theory by doing an if (MessageQue.find().count() > 0)... after the remove.
If you're set on having a separate collection for the queue, and I'm not saying that's a bad thing, I'd set the _id to be the userId. That way you can't possibly send someone the same message twice.
I'm trying to inform the subscribers when a document is removed from a collection. I use this.removed(collection, id) when removed function of observeChanges is called:
Meteor.publish('tasks_listsPub', function(sUrl){
...
var self = this;
ocTasksLists.find().observeChanges({
added: function (sId, oFields) {
console.log('added:'+sId);
self.added('tasks_lists', sId, oFields);
},
removed: function (sId) {
console.log('removed:'+sId);
self.removed('tasks_lists', sId); //throws a exception but sometimes it works in the browser
},
changed: function(sId, oFields){
console.log('changed:'+sId);
self.changed('tasks_lists', sId, oFields);
}
});
var cVisibleTasksLists = ocTasksLists.find({_id: {$in: oWs.tasks_lists}});
return cVisibleTasksLists;
});
The problem is that server throws exception:
removed:K8BBys7WRH4tTQRBg
Exception in queued task: Error: Removed nonexistent document K8BBys7WRH4tTQRBg
at _.extend.removed (app/packages/livedata/livedata_server.js:181:17)
and the other browsers sometimes does not remove the deleted document. Any solution? Thx
You appear to be publishing two conflicting datasets within one publish function.
The self.added, self.removed, and self.changed functions inside the observeChanges is trying to keep the client updated with everything in ocTasksLists.
return cVisibleTasksLists; however is trying to only publish the subset of ocTasksLists that match your query.
These conflicting publish instructions lead to the client sometimes not having all documents that are removed from ocTasksLists - your error message results.
Whether you want the whole dataset or the subset either can be done just by returning the database cursor as you do in your last two lines. Removing the observeChanges function along with .added, .removed, and .changed functions will fix your error.
I'm doing a simple insert into a meteor collection that appears work, but leaves the collection empty.
The collection is defined properly on the server:
Meteor.publish("comments", function () {
return Comments.find();
});
Subscribed to properly in the client.js:
Meteor.subscribe("commments");
And set up properly on the model.js:
Comments = new Meteor.Collection("comments");
The insert code is as follows:
Meteor.methods({
addComment: function (options) {
check(options.post_id, String);
check(options.comment, NonEmptyString);
if (! this.userId)
throw new Meteor.Error(403, "You must be logged in to comment.");
if (options.comment.length > 1000)
throw new Meteor.Error(413, "Comment is too long");
var post = Posts.findOne(options.post_id);
if (! post)
throw new Meteor.Error(404, "No such post");
// add new comment
var timestamp = (new Date()).getTime();
console.log('Comment: ' + options.comment);
console.log('Post: ' + options.post_id);
console.log('UserId: ' + this.userId);
var saved = Comments.insert({
owner: this.userId,
post_id: options.post_id,
timestamp: timestamp,
text: options.comment});
console.log('Saved: ' + saved);
}
});
Once the insert is called, the console prints out the following:
Comment: Something
Post: xRjqaBBEMa6qjGnDm
UserId: SCz9e6zrpcQrKXYWX
Saved: FCxww9GsrDsjFQAGF
> Comments.find().count()
0
I have inserts into several other collections that work just fine (Posts being one of them as you can see the post ID in the code). In the docs ist said that if the insert errors out it will print to the console, but as you can see it appears to be working, yet is actually empty.
Thanks.
UPDATE: I did find that the data is being put into the database, but for some reason is not showing up. I'm not sure why the data is not being published properly since there are no filters on the find().
I'm not sure exactly what's wrong, but there's a few things to check here.
• First, this:
Meteor.publish("comments", function () {
return Comments.find();
});
directs the server to publish the Collection, but doesn't actually establish the collection server side.
You should have Comments = new Meteor.Collection("comments"); available on both the client and the server. I tend to put in a file called model.js like the examples tend to do.
• Second possibility, you don't have a subscribe function shown above, such as Meteor.subscribe("comments"); If you don't have a subscribe function, your client isn't going to know about it, even though it does exist in the collection.
You can test this theory by typing meteor mongo in the shell (with your Meteor app running), and db.comments.find() to see if your comments are actually in the database but not subscribed to.
Verify you do not have an error in your client code. With Meteor.call, if you do not initialize a variable you can have an error condition that will block reactive updating in your templates but continue to write fine to your console just before hand.
I've made that mistake which I talk about here:
http://doctormehmet.blogspot.com/2013/07/revoltdc-hackathon-20130622-iteration-3.html
Specifically I had something like
Template.mytemplate.helpers({
somevar: function({
if (some_session_var_set_by_a_call.party){
//do something
}
}
Now the somevar function gets called on render, before the Meteor.call returns. Therefore the variable some_session_var_set_by_a_call isn't set yet. The whole thing stops client side on the undefined error.