I want to build a website like Facebook style, and for start i am building a chat system using ajax. For now, all the messages that are sent to the chat system are saved in a xml file which looks like this:
<messages>
<message from="jhon" time="2:00">Hi!</message>
</messages>
My question is if it is fine to use the xml file like i do here, or a database is the solution. Can someone explain to me how to use xml in the right way also in the chat or a messages system if it is necessary at all?
Thank you!
I made an exercise (for school) that worked in a simular way:
<post>
<time>15:25</time>
<name>myUserName</name>
<message>testbla</message>
</post>
I used a PHP-script (provided by the teacher) to write in the file (in the format like before) each time there is a new message being sent by the user. While it was working well, there were a few problems I encountered:
In order to keep the chat updated, I had to reload the chat 3600 times per hour. This is no problem. However, because I was using XML, I had to download the file 3600x per hour, which is definitely not an elegant solution; with only a few messages, the site consumed about 20-40 MB data each hour. (you do the math!)
There were also issues with the special chars that conflicted to XML: <, > and &. I had to either escape them, remove them from the user input OR use CDATA to prevent XML from crashing due to syntax errors. (XML is very sensitive for this!) Additional difficulty was to prevent that others could send bad code. Generally, try to eliminate this while updating your XML-file.
With the above in mind, I would recommend searching for a more elegant solution than XML; JSON might be lighter to handle. Alternatively, MYSQL/PHP allow you to send only the last messages, so you don't have to send the whole file over and over again. (I don't have any PHP/MYSQL-expertise at this moment, so I cannot help you with that right now)
You asked how you could make your XML-chat happen. To give you some direction, I will give you some snippets of my code (with jQuery):
/* this function gets chat logs from XML and manipulate the content to a
div used for the chat-content. It is being evaluated each second by
an interval that calls the function each 1000 ms. (not included in this code) */
function getChatLogs() {
var chatLogs = "";
$.ajax({
url: "chat_log.xml",
success: function(data) {
$(data).find("post").each(function() {
var timeMessage = $(this).find("time").text();
var nameSender = $(this).find("name").text();
var contentMessage = $(this).find("message").text();
chatLogs += "<article><time>" + timeMessage + "</time> <strong>" + nameSender + "</strong> <p>" + contentMessage+ "</p></article>";
});
$("#chat").html(chatLogs);
}
});
}
/* this function handles messages being send by the user */
function sendInput(keyCode) {
if(keyCode === 13 && $("#post").val() != "") {
var name = localStorage.getItem("username"); // I used localstorage fo username
var time = currentTime();
var message = $("#post").val();
$.ajax({
type: "POST",
url: "save.php",
data: {"name": name, "time": time, "message": message},
success: function(data) {
$("#post").val(""); // (clear the chat-input)
}
});
}
}
Bonus tip: you XML-file MUST be well formed. You can easily check if this is the case by opening the XML-file straight in Chrome. If there are issues, it will give an error.
Related
const TeleBot = require('telebot');
const bot = new TeleBot({
token: 'i9NhrhCQGq7rxaA' // Telegram Bot API token.
});
bot.on(/^([Hh]ey|[Hh]oi|[Hh]a*i)$/, function (msg) {
return bot.sendMessage(msg.from.id, "Hello Commander");
});
var Historiepics = ['Schoolfotos/grr.jpg', 'Schoolfotos/boe.jpg',
'Schoolfotos/tobinsexy.jpg'];
console.log('Historiepics')
console.log(Math.floor(Math.random() * Historiepics.length));
var foto = Historiepics[(Math.floor(Math.random() * Historiepics.length))];
bot.on(/aap/, (msg) => {
return bot.sendPhoto(msg.from.id, foto);
});
bot.start();
The result I'm getting from this is just one picture everytime, but if I ask for another random picture it keeps showing me the same one without change.
I recently figured this out, so I'll drop an answer for anyone that runs into this issue.
The problem is with Telegram's cache. They cache images server side so that they don't have to do multiple requests to the same url. This protects them from potentially getting blacklisted for too many requests, and makes things snappier.
Unfortunately if you're using an API like The Cat API this means you will be sending the same image over and over again. The simplest solution is just to somehow make the link a little different every time. This is most easily accomplished by including the current epoch time as a part of the url.
For your example with javascript this can be accomplished with the following modifications
bot.on(/aap/, (msg) => {
let epoch = (new Date).getTime();
return bot.sendPhoto(msg.from.id, foto + "?time=" + epoch);
});
Or something similar. The main point is, as long as the URL is different you won't receive a cached result. The other option is to download the file and then send it locally. This is what Telebot does if you pass the serverDownload option into sendPhoto.
I really love the DropZoneJS component and am currently wrapping it in an EmberJS component (you can see demo here). In any event, the wrapper works just fine but I wanted to listen in on one of Dropzone's events and introspect the file contents (not the meta info like size, lastModified, etc.). The file type I'm dealing with is an XML file and I'd like to look "into" it to validate before sending it.
How can one do that? I would have thought the contents would hang off of the file object that you can pick up on many of the events but unless I'm just missing something obvious, it isn't there. :(
This worked for me:
Dropzone.options.PDFDrop = {
maxFilesize: 10, // Mb
accept: function(file, done) {
var reader = new FileReader();
reader.addEventListener("loadend", function(event) { console.log(event.target.result);});
reader.readAsText(file);
}
};
could also use reader.reaAsBinaryString() if binary data!
Ok, I've answer my own question and since others appear interested I'll post my answer here. For a working demo of this you can find it here:
https://ui-dropzone.firebaseapp.com/demo-local-data
In the demo I've wrapped the Dropzone component in the EmberJS framework but if you look at the code you'll find it's just Javascript code, nothing much to be afraid of. :)
The things we'll do are:
Get the file before the network request
The key thing we need become familiar with is the HTML5 API. Good news is it is quite simple. Take a look at this code and maybe that's all you need:
/**
* Replaces the XHR's send operation so that the stream can be
* retrieved on the client side instead being sent to the server.
* The function name is a little confusing (other than it replaces the "send"
* from Dropzonejs) because really what it's doing is reading the file and
* NOT sending to the server.
*/
_sendIntercept(file, options={}) {
return new RSVP.Promise((resolve,reject) => {
if(!options.readType) {
const mime = file.type;
const textType = a(_textTypes).any(type => {
const re = new RegExp(type);
return re.test(mime);
});
options.readType = textType ? 'readAsText' : 'readAsDataURL';
}
let reader = new window.FileReader();
reader.onload = () => {
resolve(reader.result);
};
reader.onerror = () => {
reject(reader.result);
};
// run the reader
reader[options.readType](file);
});
},
https://github.com/lifegadget/ui-dropzone/blob/0.7.2/addon/mixins/xhr-intercept.js#L10-L38
The code above returns a Promise which resolves once the file that's been dropped into the browser has been "read" into Javascript. This should be very quick as it's all local (do be aware that if you're downloading really large files you might want to "chunk" it ... that's a more advanced topic).
Hook into Dropzone
Now we need to find somewhere to hook into in Dropzone to read the file contents and stop the network request that we no longer need. Since the HTML5 File API just needs a File object you'll notice that Dropzone provides all sorts of hooks for that.
I decided on the "accept" hook because it would give me the opportunity to download the file and validate all in one go (for me it's mainly about drag and dropping XML's and so the content of the file is a part of the validation process) and crucially it happens before the network request.
Now it's important you realise that we're "replacing" the accept function not listening to the event it fires. If we just listened we would still incur a network request. So to **overload* accept we do something like this:
this.accept = this.localAcceptHandler; // replace "accept" on Dropzone
This will only work if this is the Dropzone object. You can achieve that by:
including it in your init hook function
including it as part of your instantiation (e.g., new Dropzone({accept: {...})
Now we've referred to the "localAcceptHandler", let me introduce it to you:
localAcceptHandler(file, done) {
this._sendIntercept(file).then(result => {
file.contents = result;
if(typeOf(this.localSuccess) === 'function') {
this.localSuccess(file, done);
} else {
done(); // empty done signals success
}
}).catch(result => {
if(typeOf(this.localFailure) === 'function') {
file.contents = result;
this.localFailure(file, done);
} else {
done(`Failed to download file ${file.name}`);
console.warn(file);
}
});
}
https://github.com/lifegadget/ui-dropzone/blob/0.7.2/addon/mixins/xhr-intercept.js#L40-L64
In quick summary it does the following:
read the contents of the file (aka, _sendIntercept)
based on mime type read the file either via readAsText or readAsDataURL
save the file contents to the .contents property of the file
Stop the send
To intercept the sending of the request on the network but still maintain the rest of the workflow we will replace a function called submitRequest. In the Dropzone code this function is a one liner and what I did was replace it with my own one-liner:
this._finished(files,'locally resolved, refer to "contents" property');
https://github.com/lifegadget/ui-dropzone/blob/0.7.2/addon/mixins/xhr-intercept.js#L66-L70
Provide access to retrieved document
The last step is just to ensure that our localAcceptHandler is put in place of the accept routine that dropzone supplies:
https://github.com/lifegadget/ui-dropzone/blob/0.7.2/addon/components/drop-zone.js#L88-L95
using the FileReader() solution is working amazingly good for me:
Dropzone.autoDiscover = false;
var dz = new Dropzone("#demo-upload",{
autoProcessQueue:false,
url:'upload.php'
});
dz.on("drop",function drop(e) {
var files = [];
for (var i = 0; i < e.dataTransfer.files.length; i++) {
files[i] = e.dataTransfer.files[i];
}
var reader = new FileReader();
reader.onload = function(event) {
var line = event.target.result.split('\n');
for ( var i = 0; i < line.length; i++){
console.log(line);
}
};
reader.readAsText(files[files.length-1]);
I am working on New web application which is Using Web API as Business Layer and Knock out Js as client side frame work to binding. I have a requirement like Pass the certain search criteria to Web API Controller and get the Data from DB and Create and Send the Excel/MS-Word file on the fly as a downloadable content.
I am new to both the Web API and Knock out, I am searching on the Net and get partial solution and I am looking here to get more optimal solution for this use case.
Below is my code:
Client:
function GetExcelFile() {
var $downloadForm = $("<form method='POST'>")
.attr("action", baseUrl + "api/FileHandler/GetExcelFileTest")
.attr("target", "_blank")
$("body").append($downloadForm);
$downloadForm.submit();
$downloadForm.remove();
}
On Button Click having this code snippet to create a form on the fly and Get response from Web API.
Web API Code:
[HttpPost]
public HttpResponseMessage GetExcelFileTest()
{
var response = new HttpResponseMessage();
//Create the file in Web App Physical Folder
string fileName = Guid.NewGuid().ToString() + ".xls";
string filePath = HttpContext.Current.Server.MapPath(String.Format("~/FileDownload/{0}", fileName));
StringBuilder fileContent = new StringBuilder();
//Get Data here
DataTable dt = GetData();
if (dt != null)
{
string str = string.Empty;
foreach (DataColumn dtcol in dt.Columns)
{
fileContent.Append(str + dtcol.ColumnName);
str = "\t";
}
fileContent.Append("\n");
foreach (DataRow dr in dt.Rows)
{
str = "";
for (int j = 0; j < dt.Columns.Count; j++)
{
fileContent.Append(str + Convert.ToString(dr[j]));
str = "\t";
}
fileContent.Append("\n");
}
}
// write the data into Excel file
using (StreamWriter sw = new StreamWriter(fileName.ToString(), false))
{
sw.Write(fileContent.ToString());
}
IFileProvider FileProvider = new FileProvider();
//Get the File Stream
FileStream fileStream = FileProvider.Open(filePath);
//Set response
response.Content = new StreamContent(fileStream);
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
response.Content.Headers.ContentDisposition.FileName = fileName;
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/ms-excel");
response.Content.Headers.ContentLength = fileStream.Length;
//Delete the file
//if(File.Exists(filePath))
//{
// File.Delete(filePath);
//}
return response;
}
Using this code I am able to download an Excel File. Still I have some more open questions to make this code optimal.
Q1) I need to Pass view model(Search Criteria) to API Controller Using the dynamically create form ? (OR) Any better ways to get Excel file from Web API.
Q2) I am sure it's not a good way to create Excel file in Physical folder and Get FileStream and send as a respone. How to do on the fly ? OR any other optimal ways.
Please suggest me to do better ways.. Thanks
Q1) You can quite easily pass the view-model, but it's also similarly easy to pull that information from the posted form.
Passing the view-model
If you want to pass the view-model to a WebAPI method then remember that said method must take as a parameter an object with the same properties. So if the object that you wish to post back always has the same properties then it's trivial to build a server-side class with the same properties and receive an instance of that class.
To post back this client-side object you can do something like this (uses jQuery, which I see you're already using):
$.ajax({
contentType: "application/json",
data: my-view-model.toJSON(),
type: "POST",
url: baseUrl + "api/FileHandler/GetExcelFileTest" });
I haven't attached any success or error handlers here because the JavaScript isn't concerned with the return, but you might wish to add some handlers in case an exception is thrown in your WebAPI method. I recommend doing that by adding the following to the above $.ajax() call:
statusCode: {
500: function(jqXhr, textStatus, errorThrown) {
},
[other HTTP error codes]
}
[Read the documentation for the $.ajax() call here.]
One additional tip here: when you call my-view-model.toJSON() (or self.toJSON(), if called from within your view-model) Knockout will first of all determine if your view-model contains a toJSON() method. If so, it will use this method; if not then it will call the browser's implementation of this function. However, the browser's implementation of this function will serialise everything, which can be particularly length if you have, for example, long select lists in your view-model. Therefore, if you wish only to send back a subset of the view-model's properties then define your own toJSON function on your view-model like so:
var toJSON = function() {
return {
Property1: ...,
Property2: ...
};
}
[Read more about converting a view-model to JSON here.]
Posting the form as-is
If you don't wish to expend the effort to do the view-model wiring then you can just post the form exactly like you have in your question. You can then retrieve the values from the form by using
Request.Form["my-field"];
Q2)
You're probably right in pointing out that it's not wise to create the Excel file in the physical folder. However, as far as I'm aware (interested if someone says otherwise) you'll have to use a 3rd-party library for this. Microsoft do offer an Office automation library but I have a suspicion that you also need Office to be installed at the same location.
Creating Excel spreadsheets dynamically is something I've done several times but for the actual creation I use Aspose.Cells, which requires a license. Although I do create a physical version and then delete it, I believe Aspose.Cells may allow you to create it as a stream. But take a look around, there are certainly other libraries which offer Excel automation.
Returning the File from the Server
Calling $.ajax({...}) alone won't allow you to present the user with a "Save as..." dialog. What I do in this situation - and this won't work if you wish to store the generated file only in memory (FileStream, for example) and not on the file system - is to respond to the $.ajax({...}) call with a filename for the generated file.
The next step is to direct the user towards that filename.
So I have something like this in my JavaScript:
$.ajax({
dataType: "json",
type: "GET", // you'll probably want POST in your case
url: ...,
success: function(response) {
if (response && response.Uri && response.Uri.length) {
window.location.href = [root URL] + response.Uri;
}
}
});
But don't be alarmed by this redirect. That window.location.href points directly to a folder on the server, no controller needed. Because the browser then receives a file it presents the "Save as..." dialog while remaining on the same webpage.
So I'm building a multipart form uploader over ajax on node.js, and sending progress events back to the client over socket.io to show the status of their upload. Everything works just fine until I have multiple clients trying to upload at the same time. Originally what would happen is while one upload is going, when a second one starts up it begins receiving progress events from both of the forms being parsed. The original form does not get affected and it only receives progress updates for itself. I tried creating a new formidable form object and storing it in an array along with the socket's session id to try to fix this, but now the first form stops receiving events while the second form gets processed. Here is my server code:
var http = require('http'),
formidable = require('formidable'),
fs = require('fs'),
io = require('socket.io'),
mime = require('mime'),
forms = {};
var server = http.createServer(function (req, res) {
if (req.url.split("?")[0] == "/upload") {
console.log("hit upload");
if (req.method.toLowerCase() === 'post') {
socket_id = req.url.split("sid=")[1];
forms[socket_id] = new formidable.IncomingForm();
form = forms[socket_id];
form.addListener('progress', function (bytesReceived, bytesExpected) {
progress = (bytesReceived / bytesExpected * 100).toFixed(0);
socket.sockets.socket(socket_id).send(progress);
});
form.parse(req, function (err, fields, files) {
file_name = escape(files.upload.name);
fs.writeFile(file_name, files.upload, 'utf8', function (err) {
if (err) throw err;
console.log(file_name);
})
});
}
}
});
var socket = io.listen(server);
server.listen(8000);
If anyone could be any help on this I would greatly appreciate it. I've been banging my head against my desk for a few days trying to figure this one out, and would really just like to get this solved so that I can move on. Thank you so much in advance!
Can you try putting console.log(socket_id);
after form = forms[socket_id]; and
after progress = (bytesReceived / bytesExpected * 100).toFixed(0);, please?
I get the feeling that you might have to wrap that socket_id in a closure, like this:
form.addListener(
'progress',
(function(socket_id) {
return function (bytesReceived, bytesExpected) {
progress = (bytesReceived / bytesExpected * 100).toFixed(0);
socket.sockets.socket(socket_id).send(progress);
};
})(socket_id)
);
The problem is that you aren't declaring socket_id and form with var, so they're actually global.socket_id and global.form rather than local variables of your request handler. Consequently, separate requests step over each other since the callbacks are referring to the globals rather than being proper closures.
rdrey's solution works because it bypasses that problem (though only for socket_id; if you were to change the code in such a way that one of the callbacks referenced form you'd get in trouble). Normally you only need to use his technique if the variable in question is something that changes in the course of executing the outer function (e.g. if you're creating closures within a loop).
I am trying to use the multiple upload attribute of HTML5 to upload files.
I know it wouldn't work with IE and fall back to single file upload.
also I found some invalid html tag like min max allows opera to do the same.
I am trying to do the following:
The browse button be capable of selecting multiple files.
But the ajax should send files one by one.
My scenario is something like this:
the user selects 5 files and starts the upload . Now the ajax should firstfile send the first file, then second, and so on.
The server side script does something with the file and returns some data.
now as soon as one file upload is completed it must render that part of the result.
So as the user selects images and starts uploading the results come out as soon as each file is uploaded (and not after all the files are uploaded).
I tried something like this :
function handleFiles(files)
{ alert(files.length); //properly returns the number of files selected
for (var i = 0; i < files.length; i++) {
new FileUpload(files[i])
}
}
function FileUpload(file) {
var reader = new FileReader();
var xhr = new XMLHttpRequest();
this.xhr = xhr;
xhr.open("POST", "portfolio/add_media");
reader.onload = function(evt) {
xhr.sendAsBinary(evt.target.result);
};
reader.readAsBinaryString(file);
}
after reading the tutorial at mozilla but I end up with missing params.
. so can some one suggest me a clean solution to this
Some more details :
When I pass a single file ( with no multiple attribute ) my server recieves :
"image"=>[# < ActionDispatch::Http::UploadedFile:0x10d55be8
#tempfile=#< File:C:/Users/Gaurav/AppData/Local/Temp/RackMultipart20110701-1916-2ly4k2-0>,
#headers="Content-Disposition:
form-data; name=\"picture[image][]\";
filename=\"Desert.jpg\"\r\nContent-Type:
image/jpeg\r\n",
#content_type="image/jpeg",
#original_filename="Desert.jpg">]}}
But when I use multiple attribute and send using xhr I am able to get only one file param. How do I get the rest of the params ? esp the action dispatch thingy
You are simply sending the file data to the server, without encoding it in any way. For the server to know how to process it you need to encode your data properly (multipart/form-data encoding). Easiest way is using a FormData object: https://developer.mozilla.org/En/Using_XMLHttpRequest#Sending_files_using_a_FormData_object. Only that instead of data.append("CustomField", "This is some extra data") you would write data.append("file1", event.target.result).