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  • ASP.Net MVC - bulk / batch insert with through controller

    - by user610358
    guys, I need to make a view which will support bulk insert. In my mvc app, I am using repository patern with entity framework for. I am only having problem on how I will going to retrive the values of the model. There will be multiple model inpouts inside the view. I am sure that I am going to use foreach or for loop but how I am going to retrive the input values form view into controller. any help would be appreciated. thanks.

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  • Traversable => Java Iterator

    - by Andres
    I have a Traversable, and I want to make it into a Java Iterator. My problem is that I want everything to be lazily done. If I do .toIterator on the traversable, it eagerly produces the result, copies it into a List, and returns an iterator over the List. I'm sure I'm missing something simple here... Here is a small test case that shows what I mean: class Test extends Traversable[String] { def foreach[U](f : (String) => U) { f("1") f("2") f("3") throw new RuntimeException("Not lazy!") } } val a = new Test val iter = a.toIterator

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  • Silverlight/WPF: Retreiving the size of a `UIElement` once it has been rendered on screen

    - by ondesertverge
    I have the following simple piece of code: var canvas = new Canvas(); foreach (var ztring in strings) { var textblock = new TextBlock(); textblock.Text = ztring; panel.Children.Add(textblock); textblock.Measure(infiniteSize); } At this point I would expect any of the size properties (Height/Width, ActualHeight/ActualWidth, DesiredSize, RenderSize) to give me the size of the textblock. None of them do. ActualHeight always gives 16.0 no matter what size font. ActualWidth changes according to the text length but not the font size. I change the font size on the parent container and not the TextBlock itself. I feel like I am missing some basic element of understanding the manipulation of silverlight elements from within the codebehind. The question is: how do I get the real actual pixel size of my TextBlock?

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  • Finding the attributes on the properties of an instance of a class

    - by Dan
    Given an instance of a class I want to set properties on attributes at runtime. So I tried this, but as far as I can tell this finds the attributes on the class not the instance, so any changes I make to the attribute properties have no effect. var properties = myObject.GetType().GetProperties(); foreach (object prop in properties) { var attribute =prop.GetCustomAttributes(typeof(MyAttribute), true)[0]; //attribute.MyProp do some stuff } If I try using type descriptor like below, there is no way of getting to the attributes on the properties. var myObject= (MyClass) object; PropertyDescriptorCollection props = TypeDescriptor.GetProperties(myObject); //There is no props[0].GetCustomAttributes(

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  • magento success page variables

    - by user1799790
    I am trying to capture some magento success page variables to pass to our advertising company. So far I have got this but the variables are not outputting anything: <?php $items = $order->getItemsCollection(); foreach ($items as $item) { $price="'".$item->getPrice()."', "; $qty="'".$item->getQty()."', "; $sku="'".$item->getSku()."', "; } ?> The data needs to be in the format: 'price1', 'price2', 'price3' 'qty1', 'qty2', 'qty3' 'sku1', 'sku2', 'sku3'

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  • how to insert page view of a node in another page in drupal

    - by sprugman
    I have a list of node ids and I want to display the 'page' view of each one. For various reasons, I don't want to do this with views, and don't think I should need a module. Just an API call to theme('node'). Something like: $nids = array(3,4,5); foreach ($nids as $nid) { $node = node_load($nid); $result .= theme('node', $node); } but I'm not getting back the full page view of the node. I added this to my node-[type].tpl.php file: if ($page) print "PAGE MODE "; else print "NOT PAGE "; if ($teaser) print "TEASER MODE "; else print "NOT TEASER "; and got: NOT PAGE NOT TEASER I seem to be in some kind of limbo. I suspect there's an argument that I add to the theme function, but the terms are all so general (theme, teaser, page, node), I'm having trouble with my google-fu.

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  • How to save checkbox checked values in Database

    - by user1298215
    How to save checkbox values in database. Below is my view code. @foreach (var item in Model) { @Html.CheckBox("statecheck", (IEnumerable<SelectListItem>)ViewData["StatesList"]) @Html.DisplayFor(modelItem => item.state_name) </br> } <input class="ASPbutton" type="submit" value="submit"/> Below is My controller. public ActionResult States() { ViewData["StatesList"] = new SelectList(am.FindUpcomingStates().ToList(), "state_id", "state_Name"); return View(); } My model is public IQueryable<state> FindUpcomingStates() { return from state in Adm.states orderby state.state_name select state; } After clicking submit button checked item state_id will be saved into database. I wrote like below in Controller, but i got true or false values, i want state_id [AcceptVerbs(HttpVerbs.Post)] public ActionResult States(string _stateName, char[] statecheck, FormCollection formvalues) { statecheck = Request.Form["statecheck"].ToArray(); ViewData["StatesList"] = new SelectList(am.FindUpcomingStates222().ToList(), "state_id", "state_id", _stateName); }

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  • How to find the formula of best case and worst case of my algorithm?

    - by rachel7660
    I was given a task. Write an algorithm so that, the input of 2 lists of data, will have at least one in common. So, this is my algorithm: (I write the code in php) $arrayA = array('5', '6', '1', '2', '7'); $arrayB = array('9', '2', '1', '8', '3'); $arrayC = array(); foreach($arrayA as $val){ if(in_array($val, $arrayB)){ array_push($arrayC, $val); } } Thats my own algo, not sure if its a good one. So, based on my algorithm, how to find the formula of best case and worst case (big O)? Note: Please do let me know, if my algorithm is wrong. My goal is " input of 2 lists of data, will have at least one in common."

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  • How can I kill a Perl system call after a timeout?

    - by Fergal
    I've got a Perl script I'm using for running a file processing tool which is started using backticks. The problem is that occasionally the tool hangs and It needs to be killed in order for the rest of the files to be processed. Whats the best way best way to apply a timeout after which the parent script will kill the hung process? At the moment I'm using: foreach $file (@FILES) { $runResult = `mytool $file >> $file.log`; } But when mytool hangs after n seconds I'd like to be able to kill it and continue to the next file.

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  • A Better way? Finding ASP.NET controls, finding their id

    - by CSharp
    I have a method that finds all the controls, iterates through them, determines if they are a textbox,drop down list, etc.. retrieves their ID name, and depending on the ID name it will set a boolean statement (thus I would know if that section of the form is complete, and will email to a certain group of people) unfortunetly this is done with too many if statements and was wondering if I could get some help making this more manageable protected void getEmailGroup() { Control[] allControls = FlattenHierachy(Page); foreach (Control control in allControls) { if (control.ID != null) { if (control is TextBox) { TextBox txt = control as TextBox; if (txt.Text != "") { if (control.ID.StartsWith("GenInfo_")) { GenInfo = true; } if (control.ID.StartsWith("EmpInfo_")) { EmpInfo = true; } } } if (control is DropDownList) { DropDownList lb = control as DropDownList; if (lb.SelectedIndex != -1) { if (control.ID.StartsWith("GenInfo_")) { GenInfo = true; } if (control.ID.StartsWith("EmpInfo_")) { EmpInfo = true; } } } } } }

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  • parsing a xml to get some values

    - by Joan Silverstone
    Hello, i have this xml: http://www.managerleague.com/export_data.pl?data=transfers&output=xml&hide_header=0 These are player sales from a browser game. I want to save some fields from these sales. I am fetching that xml with curl and storing on my server. Then do the following: $xml_str = file_get_contents('salespage.xml'); $xml = new SimpleXMLElement($xml_str); $items = $xml->xpath('*/transfer'); print_r($items); foreach($items as $item) { echo $item['buyerTeamname'], ': ', $item['sellerTeamname'], "\n"; } The array is empty and i cant seem to get anything from it. What am i doing wrong?

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  • Type casting Collections using Conversion Operators

    - by Vyas Bharghava
    The below code gives me User-defined conversion must convert to or from enclosing type, while snippet #2 doesn't... It seems that a user-defined conversion routine must convert to or from the class that contains the routine. What are my alternatives? Explicit operator as extension method? Anything else? public static explicit operator ObservableCollection<ViewModel>(ObservableCollection<Model> modelCollection) { var viewModelCollection = new ObservableCollection<ViewModel>(); foreach (var model in modelCollection) { viewModelCollection.Add(new ViewModel() { Model = model }); } return viewModelCollection; } Snippet #2 public static explicit operator ViewModel(Model model) { return new ViewModel() {Model = model}; } Thanks in advance!

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  • How to batch retrieve documents with mongoDB?

    - by edude05
    Hello everyone, I have an application that queries data from a mongoDB using the mongoDB C# driver something like this: public void main() { foreach (int i in listOfKey) { list.add(getObjectfromDB(i); } } public myObject getObjFromDb(int primaryKey) { document query = new document(); query["primKey"] = primaryKey; document result= mongo["myDatabase"]["myCollection"].findOne(query); return parseObject(result); } On my local (development) machine to get 100 object this way takes less than a second. However, I recently moved the database to a server on the internet, and this query takes about 30 seconds to execute for the same number of object. Furthermore, looking at the mongoDB log, it seems to open about 8-10 connections to the DB to perform this query. So what I'd like to do is have the query the database for an array of primaryKeys and get them all back at once, then do the parsing in a loop afterwards, using one connection if possible. How could I optimize my query to do so? Thanks, --Michael

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  • How to properly override Drupal imagecache presets

    - by volocuga
    Say I need to override defaul presets, provided by Ubercart module. This is what I wrote: function config_imagecache() { $presets = array( array( 'presetname' => 'product', 'actions' => array( array( 'action' => 'imagecache_crop', 'data' => array('width' => 300, 'height' => ''), 'weight' => 0, 'module' => 'imagecache', ), array( 'action' => 'canvasactions_canvas2file', 'data' => array('xpos' => 'center', 'ypos' => 'center', 'path' => 'actions/pad_300_300.gif', 'dimensions' => 'background',), 'weight' => 1, 'module' => 'imagecache_canvasactions', ), ), ), array( 'presetname' => 'uc_thumbnail', 'actions' => array( array( 'action' => 'imagecache_scale', 'data' => array('width' => 55, 'height' => 55, 'upscale' => 0), 'weight' => 0, 'module' => 'imagecache', ), array( 'action' => 'canvasactions_canvas2file', 'data' => array('xpos' => 'center','ypos' => 'center', 'path' => 'actions/pad_60_60.gif','dimensions' => 'background'), 'weight' => 1, 'module' => 'imagecache_canvasactions', ), ), ), array( 'presetname' => 'product_full', 'actions' => array( array( 'action' => 'imagecache_scale', 'data' => array('width' => 600, 'height' => 600, 'upscale' => 0), 'weight' => 0, 'module' => 'imagecache', ), ), ), array( 'presetname' => 'product_list', 'actions' => array( array( 'action' => 'imagecache_scale', 'data' => array('width' => 100, 'height' => 100, 'upscale' => 0), 'weight' => 0, 'module' => 'imagecache', ), array( 'action' => 'canvasactions_canvas2file', 'data' => array('xpos' => 'center', 'ypos' => 'center', 'path' => 'actions/pad_100_100.jpg','dimensions' => 'background',), 'weight' => 1, 'module' => 'imagecache_canvasactions', ), ), ), array( 'presetname' => 'uc_category', 'actions' => array( array( 'action' => 'imagecache_scale', 'data' => array('width' => 100, 'height' => 100, 'upscale' => 0), 'weight' => 0, 'module' => 'imagecache', ), array( 'action' => 'canvasactions_canvas2file', 'data' => array('xpos' => 'center', 'ypos' => 'center', 'path' => 'actions/pad_100_100.gif', 'dimensions' => 'background',), 'weight' => 1, 'module' => 'imagecache_canvasactions', ), ), ), array( 'presetname' => 'cart', 'actions' => array( array( 'action' => 'imagecache_scale', 'data' => array('width' => 50, 'height' => 50, 'upscale' => 0), 'weight' => 0, 'module' => 'imagecache', ), array( 'action' => 'canvasactions_canvas2file', 'data' => array('xpos' => 'center', 'ypos' => 'center', 'path' => 'actions/pad_60_60.gif', 'dimensions' => 'background',), 'weight' => 1, 'module' => 'imagecache_canvasactions', ), ), ), ); foreach ($presets as $preset) { drupal_write_record('imagecache_preset', $preset); foreach ($preset['actions'] as $action) { $action['presetid'] = $preset['presetid']; drupal_write_record('imagecache_action', $action); } } imagecache_presets(true); cache_clear_all('imagecache:presets', 'cache'); } I can see in imagecache UI the settings was applied, but really images disappeared at all. Nothing works now. Where is the mistake?

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  • Trim email list into domain list

    - by hanjaya
    The function below is part of a script to trim email list from a file into domain list and removes duplicates. /* define a function that can accept a list of email addresses */ function getUniqueDomains($list) { // iterate over list, split addresses and add domain part to another array $domains = array(); foreach ($list as $l) { $arr = explode("@", $l); $domains[] = trim($arr[1]); } // remove duplicates and return return array_unique($domains); } What does $domains[] = trim($arr[1]); mean? Specifically the $arr[1]. What does [1] mean in this context? How come variable $arr becomes an array variable?

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  • c#: sms appears to have been sent, but stuck in phone outbox

    - by I__
    i wrote code to send an SMS using my gsm phone which is attached to the computer through com port. the code is below. the problem is i do see that it is in the outbox of the phone and it actually appears to have been sent, but when i contact the recipient they say that i have not received the message. i test the phone, and i create and send a message using only the phone and it works perfectly, however when i do this with my code, it APPEARS to have been sent, and i am getting all the correct AT COMMAND responses from the phone, but the message is actually NOT sent. here is the code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; using System.IO.Ports; namespace WindowsFormsApplication1 { public partial class Form1 : Form { SerialPort serialPort1; int m_iTxtMsgState = 0; const int NUM_MESSAGE_STATES = 4; const string RESERVED_COM_1 = "COM1"; const string RESERVED_COM_4 = "COM4"; public Form1() { InitializeComponent(); this.Closing += new CancelEventHandler(Form1_Closing); } private void Form1_Load(object sender, EventArgs e) { serialPort1 = new SerialPort(GetUSBComPort()); if (serialPort1.IsOpen) { serialPort1.Close(); } serialPort1.Open(); //ThreadStart myThreadDelegate = new ThreadStart(ReceiveAndOutput); //Thread myThread = new Thread(myThreadDelegate); //myThread.Start(); this.serialPort1.DataReceived += new SerialDataReceivedEventHandler(sp_DataReceived); } private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e) { serialPort1.Close(); } private void SendLine(string sLine) { serialPort1.Write(sLine); sLine = sLine.Replace("\u001A", ""); consoleOut.Text += sLine; } public void DoWork() { ProcessMessageState(); } public void ProcessMessageState() { switch (m_iTxtMsgState) { case 0: m_iTxtMsgState = 1; SendLine("AT\r\n"); //NOTE: SendLine must be the last thing called in all of these! break; case 1: m_iTxtMsgState = 2; SendLine("AT+CMGF=1\r\n"); break; case 2: m_iTxtMsgState = 3; SendLine("AT+CMGW=" + Convert.ToChar(34) + "+9737387467" + Convert.ToChar(34) + "\r\n"); break; case 3: m_iTxtMsgState = 4; SendLine("A simple demo of SMS text messaging." + Convert.ToChar(26)); break; case 4: m_iTxtMsgState = 5; break; case 5: m_iTxtMsgState = NUM_MESSAGE_STATES; break; } } private string GetStoredSMSID() { return null; } /* //i dont think this part does anything private void serialPort1_DataReceived_1(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) { string response = serialPort1.ReadLine(); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); } */ void sp_DataReceived(object sender, SerialDataReceivedEventArgs e) { try { Thread.Sleep(500); char[] msg; msg = new char[613]; int iNumToRead = serialPort1.BytesToRead; serialPort1.Read(msg, 0, iNumToRead); string response = new string(msg); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); serialPort1.DiscardInBuffer(); if (m_iTxtMsgState == 4) { int pos_cmgw = response.IndexOf("+CMGW:"); string cmgw_num = response.Substring(pos_cmgw + 7, 4); SendLine("AT+CMSS=" + cmgw_num + "\r\n"); //stop listening to messages received } if (m_iTxtMsgState < NUM_MESSAGE_STATES) { ProcessMessageState(); } } catch { } } private void button1_Click(object sender, EventArgs e) { m_iTxtMsgState = 0; DoWork(); } private void button2_Click(object sender, EventArgs e) { string[] sPorts = SerialPort.GetPortNames(); foreach (string port in sPorts) { consoleOut.Text += port + "\r\n"; } } private string GetUSBComPort() { string[] sPorts = SerialPort.GetPortNames(); foreach (string port in sPorts) { if (port != RESERVED_COM_1 && port != RESERVED_COM_4) { return port; } } return null; } }

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  • PHP Simple XML Parse Attributes

    - by jwzk
    I have an XML file with data stored like this: <myxml> <item name="column18">88744544</item> <item name="column11">47884994</item> <item name="column3">44788894</item> </myxml> I need to first check (and be sure that) column11 is defined (there is no particular order), and then get its value. Using simple XML is not seeming to work too well. I have the following, but the value is missing. <?php if (count($xml->myxml->item) > 0) { foreach ($xml->myxml->item as $item) { var_dump($item->attributes()); } } ?>

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  • A Better way? C# finding controls, finding their id,

    - by CSharp
    I have a method that finds all the controls, iterates through them, determines if they are a textbox,drop down list, etc.. retrieves their ID name, and depending on the ID name it will set a boolean statement (thus I would know if that section of the form is complete, and will email to a certain group of people) unfortunetly this is done with too many if statements and was wondering if I could get some help making this more manageable ` protected void getEmailGroup() { Control[] allControls = FlattenHierachy(Page); foreach (Control control in allControls) { if (control.ID != null) { if (control is TextBox) { TextBox txt = control as TextBox; if (txt.Text != "") { if (control.ID.StartsWith("GenInfo_")) { GenInfo = true; } if (control.ID.StartsWith("EmpInfo_")) { EmpInfo = true; } } } if (control is DropDownList) { DropDownList lb = control as DropDownList; if (lb.SelectedIndex != -1) { if (control.ID.StartsWith("GenInfo_")) { GenInfo = true; } if (control.ID.StartsWith("EmpInfo_")) { EmpInfo = true; } } } } } }`.

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  • Is both approach same ?

    - by Harikrishna
    I have one datatable which is not bindided and records are coming from the file by parsing it in the datatable dynamically every time. Now there is three columns in the datatable Marks1,Marks2 and FinalMarks. And their types is decimal. Now for making addition of columns Marks1 and Marks2 's records and store it into FinalMarks column,For that what I do is : datatableResult.Columns["FinalMarks"].Expression="Marks1+Marks2"; It's works properly. It can be done in other way also is foreach (DataRow r in datatableResult.Rows) { r["FinalMarks"]=Convert.ToDecimal(r["Marks1"])+Convert.ToDecimal(r["Marks2"]); } Now I don't know that which is the best way to do this means performance wise. Is first approach same as second approach in background means is both approach same or what?

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  • Converting code to perl sub, but not sure I'm doing it right

    - by Ben Dauphinee
    I'm working from a question I posted earlier (here), and trying to convert the answer to a sub so I can use it multiple times. Not sure that it's done right though. Can anyone provide a better or cleaner sub? sub search_for_key { my ($args) = @_; foreach $row(@{$args->{search_ary}}){ print "@$row[0] : @$row[1]\n"; } my $thiskey = NULL; my @result = map { $args->{search_ary}[$_][0] } # Get the 0th column... grep { @$args->{search_in} =~ /$args->{search_ary}[$_][1]/ } # ... of rows where the 0 .. $#array; # first row matches $thiskey = @result; print "\nReturning: " . $thiskey . "\n"; return $thiskey; } search_for_key({ 'search_ary' => $ref_cam_make, 'search_in' => 'Canon EOS Rebel XSi' });

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  • Property changing null whilst updating a value.

    - by dinesh
    retreiveing the Data object through a class which is partial class in linq to sql. i am using the same object model to update the changes. but proprertychanging is always null for this object. An anonoymoustype has been converted into strong object type. This strong type is updated again. any one can expalin reason for this? Sample Code: var questions = from Question in _db.CheckListInstanceQuestionDataSource join Question in _db.QuestionDataSource on CheckListInstanceQuestion.UI_QuestionID equals Question.UI_QuestionID where CheckListInstanceQuestion.UI_CheckListInstanceID == instanceID && CheckListInstanceForm.UI_TemplateCheckListFormID == selectedFormID orderby CheckListInstanceQuestion.IN_Order, CheckListInstanceQuestion.VC_Code select new { Question .UI_QuestionID, Question.VC_Description, }; ICollection checkListQuestions = new List(); foreach (var question in questions) { checkListQuestions.Add(new CheckListInstanceQuestion { UI_QuestionID = question.UI_QuestionID, VC_Description = question.VC_Description, });

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  • How can I print N array elements with delimiters per line?

    - by Mark B
    I have an array in Perl I want to print with space delimiters between each element, except every 10th element which should be newline delimited. There aren't any spaces in the elements if that matters. I've written a function to do it with for and a counter, but I wondered if there's a better/shorter/canonical Perl way, perhaps a special join syntax or similar. My function to illustrate: sub PrintArrayWithNewlines { my $counter = 0; my $newlineIndex = shift @_; foreach my $item (@_) { ++$counter; print "$item"; if($counter == $newlineIndex) { $counter = 0; print "\n"; } else { print " "; } } }

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  • Need help setting up json array

    - by torr
    A database query returns several rows which I loop through as follows: foreach ($query->result() as $row) { $data[$row->post_id]['post_id'] = $row->post_id; $data[$row->post_id]['post_type'] = $row->post_type; $data[$row->post_id]['post_text'] = $row->post_text; } If I json_encode the resulting array ($a['stream']) I get { "stream": { "1029": { "post_id": "1029", "post_type": "1", "post_text": "bla1", }, "1029": { "post_id": "1030", "post_type": "3", "post_text": "bla2", }, "1029": { "post_id": "1031", "post_type": "2", "post_text": "bla3", } } } But the json should actually look like this: { "stream": { "posts": [{ "post_id": "1029", "post_type": "1", "post_text": "bla1", }, { "post_id": "1030", "post_type": "3", "post_text": "bla2", }, { "post_id": "1031", "post_type": "2", "post_text": "bla3", }] } } How should I build my array to get this json right?

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  • Index out of bounds exception in c#

    - by Naga
    I have the following code in my program which is throwing index out of bound exception at line yearList.SetValue(years[count], count); protected void invoiceYear_DataBound(object sender, EventArgs e) { //invoiceYear.SelectedItem.Value= GetYearRange(); String[] years = GetYearRange().Split(new char[] { '[', ',', ']',' ' }); ListItem [] yearList = new ListItem[]{}; System.Diagnostics.Debug.WriteLine("years-->" + years.Length); for (int i = 0; i < years.Length; i++) { System.Diagnostics.Debug.WriteLine("years-->" + years.GetValue(i)); } int count = 0; foreach (String str in years) { if (string.IsNullOrEmpty(str)) System.Diagnostics.Debug.WriteLine("empty"); else { yearList.SetValue(years[count], count); count++; } } //System.Diagnostics.Debug.WriteLine("yearList-->" + yearList.GetValue(0)); //invoiceYear.Items.AddRange(yearList); }

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  • Is multithreading the right way to go for my case?

    - by Julien Lebosquain
    Hello, I'm currently designing a multi-client / server application. I'm using plain good old sockets because WCF or similar technology is not what I need. Let me explain: it isn't the classical case of a client simply calling a service; all clients can 'interact' with each other by sending a packet to the server, which will then do some action, and possible re-dispatch an answer message to one or more clients. Although doable with WCF, the application will get pretty complex with hundreds of different messages. For each connected client, I'm of course using asynchronous methods to send and receive bytes. I've got the messages fully working, everything's fine. Except that for each line of code I'm writing, my head just burns because of multithreading issues. Since there could be around 200 clients connected at the same time, I chose to go the fully multithreaded way: each received message on a socket is immediately processed on the thread pool thread it was received, not on a single consumer thread. Since each client can interact with other clients, and indirectly with shared objects on the server, I must protect almost every object that is mutable. I first went with a ReaderWriterLockSlim for each resource that must be protected, but quickly noticed that there are more writes overall than reads in the server application, and switched to the well-known Monitor to simplify the code. So far, so good. Each resource is protected, I have helper classes that I must use to get a lock and its protected resource, so I can't use an object without getting a lock. Moreover, each client has its own lock that is entered as soon as a packet is received from its socket. It's done to prevent other clients from making changes to the state of this client while it has some messages being processed, which is something that will happen frequently. Now, I don't just need to protect resources from concurrent accesses. I must keep every client in sync with the server for some collections I have. One tricky part that I'm currently struggling with is the following: I have a collection of clients. Each client has its own unique ID. When a client connects, it must receive the IDs of every connected client, and each one of them must be notified of the newcomer's ID. When a client disconnects, every other client must know it so that its ID is no longer valid for them. Every client must always have, at a given time, the same clients collection as the server so that I can assume that everybody knows everybody. This way if I'm sending a message to client #1 telling "Client #2 has done something", I know that it will always be correctly interpreted: Client 1 will never wonder "but who is Client 2 anyway?". My first attempt for handling the connection of a new client (let's call it X) was this pseudo-code (remember that newClient is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("newClient with id X has connected"); } } clients.Add(newClient); newClient.Send("the list of other clients"); } Now imagine that in the same time, another client has sent a packet that translates into a message that must be broadcasted to every connected client, the pseudo-code will be something like this (remember that the current client - let's call it Y - is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("something"); } } } An obvious deadlock occurs here: on one thread X is locked, the clients lock has been entered, started looping through the clients, and at one moment must get Y's lock... which is already acquired on the second thread, itself waiting for the clients collection lock to be released! This is not the only case like this in the server application. There are other collections which must be kept in sync with the clients, some properties on a client can be changed by another one, etc. I tried other types of locks, lock-free mechanisms and a bunch of other things. Either there were obvious deadlocks when I'm using too much locks for safety, or obvious race conditions otherwise. When I finally find a good middle point between the two, it usually comes with very subtle race conditions / dead locks and other multi-threading issues... my head hurts very quickly since for any single line of code I'm writing I have to review almost the whole application to ensure everything will behave correctly with any number of threads. So here's my final question: how would you resolve this specific case, the general case, and more importantly: aren't I going the wrong way here? I have little problems with the .NET framework, C#, simple concurrency or algorithms in general. Still, I'm lost here. I know I could use only one thread processing the incoming requests and everything will be fine. However, that won't scale well at all with more clients... But I'm thinking more and more to go this simple way. What do you think? Thanks in advance to you, StackOverflow people which have taken the time to read this huge question. I really had to explain the whole context if I want to get some help.

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