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• Looking for best practise for writing a serial device communication app in C#

  - by cdotlister

  I am pretty new to serial comms, but would like advise on how to best achieve a robust application which speak to and listens to a serial device. I have managed to make use of System.IO.serialport, and successfully connected to, sent data to and recieved from my device. The way things work is this. My application connects to the Com Port and opens the port.... I then connect my device to the com port, and it detects a connectio to the PC, so sends a bit of text. it's really just copyright info, as well as the version of the firmware. I don't do anything with that, except display it in my 'activity' window. The device then waits. I can then query information, but sending a command such as 'QUERY PARAMETER1'. It then replies with something like: 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n' I then process that. I can then update it by sending 'SET PARAMETER1 12345', and it will reply with 'QUERY PARAMETER1\r\n\r\n12345\r\n\r\n'. All pretty basic. So, what I have done is created a Communication Class. this call is called in it's own thread, and sends data back to the main form... and also allows me to send messages to it. Sending data is easy. Recieving is a bit more tricky. I have employed the use of the datarecieved event, and when ever data comes in, I echo that to my screen. My problem is this: When I send a command, I feel I am being very dodgy in my handling. What I am doing is, lets say I am sending 'QUERY PARAMETER1'. I send the command to the device, I then put 'PARAMETER1' into a global variable, and I do a Thread.Sleep(100). On the data recieved, I then have a bit of logic that checks the incoming data, and sees if the string CONTAINS the value in the gloabl variable. As the reply may be 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n', it sees that it contains my parameter, parses the string, and returns the value I am looking for, but placing it into another global variable. My sending method was sleeping for 100ms. It then wakes, and checks the returned global variable. If it has data... then I'm happy, and I process the data. Problem is... if the sleep is too short.. it will fail. And I feel it's flakey.. putting stuff into variables.. then waiting... The other option is to use ReadLine instead, but that's very blocking. So I remove the datarecieved method, and instead... just send the data... then call ReadLine(). That may give me better results. There's no time, except when we connect initially, that data comes from the device, without me requesting it. So, maybe readline will be simpler and safer? Is this known as 'Blocking' reads? Also, can I set a timeout? Hopefully someone can guide me.

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• Web Services c#, Sending notifications Clients

  - by Diode

  I want to send a notification (say a string) to subscribers(subscribers ip addresses are in a database on the server side) by calling another method. when ever I call that method the output becomes error-some. [WebMethod] public string GetGroupPath(string emailAddress, string password, string ipAddress) { //SqlDataAdapter dbadapter = null; DataSet returnDS = new DataSet(); string groupName = null; string groupPath = null; SqlConnection dbconn = new SqlConnection("Server = localhost;Database=server;User ID = admin;Password = password;Trusted_Connection=false;"); dbconn.Open(); SqlCommand cmd = new SqlCommand(); string getGroupName = "select users.groupname from users where emailaddress = "+"'"+ emailAddress+"'"+ " and "+ "users.password = " + "'" +password+"'"; cmd.CommandText = getGroupName; cmd.Connection = dbconn; SqlDataReader reader = null; try { reader = cmd.ExecuteReader(); while (reader.Read()) { groupName = reader["groupname"].ToString(); } } catch (Exception) { groupPath = "Invalied"; } dbconn.Close(); dbconn.Open(); if (groupName != null) { string getPath = "select groups.grouppath from groups where groupname = " + "'" + groupName + "'"; cmd.CommandText = getPath; cmd.Connection = dbconn; try { reader = cmd.ExecuteReader(); while (reader.Read()) { groupPath = reader["grouppath"].ToString(); } } catch { groupPath = "Invalied"; } } else groupPath = "Invalied"; dbconn.Close(); if (groupPath != "Invalied") { dbconn.Open(); string getPath = "update users set users.ipaddress = "+"'"+ipAddress+"'"+" where users.emailaddress = " + "'" + emailAddress + "'"; cmd.CommandText = getPath; cmd.Connection = dbconn; cmd.ExecuteNonQuery(); dbconn.Close(); } NotifyUsers(); //NotifyUsers nu = new NotifyUsers(); //List<string> ipList = new List<string>(); //ipList.Add("192.168.56.1"); //nu.Notify(); return groupPath; } private void NotifyUsers() { Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); byte[] ipb = Encoding.ASCII.GetBytes("255.255.255.255"); IPAddress ipAddress = new IPAddress(ipb); IPEndPoint endPoint = new IPEndPoint(ipAddress, 15000); string notification = "new_update"; byte[] sendBuffer = Encoding.ASCII.GetBytes(notification); sock.SendTo(sendBuffer, endPoint); sock.Close(); } This is what has to be basically done. in the server side I have a listening thread and it gets notification when the server sends data( assume for now the database contains client ip address). then ever I call the web method it gives a error "invalid IPAddress" atline byte[] ipb = Encoding.ASCII.GetBytes("255.255.255.255"); thank you :) since this is my first ever post please be kind enough to give me a better feedback too :) thaks

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• sendto: Network unreachable

  - by devin

  Hello. I have two machines I'm testing my code on, one works fine, the other I'm having some problems and I don't know why it is. I'm using an object (C++) for the networking part of my project. On the server side, I do this: (error checking removed for clarity) res = getaddrinfo(NULL, port, &hints, &server)) < 0 for(p=server; p!=NULL; p=p->ai_next){ fd = socket(p->ai_family, p->ai_socktype, p->ai_protocol); if(fd<0){ continue; } if(bind(fd, p->ai_addr, p->ai_addrlen)<0){ close(fd); continue; } break; } This all works. I then make an object with this constructor net::net(int fd, struct sockaddr *other, socklen_t *other_len){ int counter; this->fd = fd; if(other != NULL){ this->other.sa_family = other->sa_family; for(counter=0;counter<13;counter++) this->other.sa_data[counter]=other->sa_data[counter]; } else cerr << "Networking error" << endl; this->other_len = *other_len; } void net::gsend(string s){ if(sendto(this->fd, s.c_str(), s.size()+1, 0, &(this->other), this->other_len)<0){ cerr << "Error Sending, " << s << endl; cerr << strerror(errno) << endl; } return; } string net::grecv(){ stringstream ss; string s; char buf[BUFSIZE]; buf[BUFSIZE-1] = '\0'; if(recvfrom(this->fd, buf, BUFSIZE-1, 0, &(this->other), &(this->other_len))<0){ cerr << "Error Recieving\n"; cerr << strerror(errno) << endl; } // convert to c++ string and if there are multiple trailing ';' remove them ss << buf; s=ss.str(); while(s.find(";;", s.size()-2) != string::npos) s.erase(s.size()-1,1); return s; } So my problem is, is that on one machine, everything works fine. On another, everything works fine until I call my server's gsend() function. In which I get a "Error: Network Unreachable." I call gercv() first before calling gsend() too. Can anyone help me? I would really appreciate it.

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• iphone web service access

  - by malleswar

  Hi, I have .net webservice methods login and summary. After getting the result from login, I need to show second view and need to call summary method. I am following this tutorial. http://icodeblog.com/2008/11/03/iphone-programming-tutorial-intro-to-soap-web-services/ I created two new classes loginaccess.h and loginaccess.m. @implementation LoginAccess @synthesize ResultString,webData, soapResults, xmlParser; -(NSString*)LoginCheck:(NSString*)userName:(NSString*)pwd { NSString *soapMessage = [NSString stringWithFormat: @"\n" "\n" "\n" "\n" "%@" "%@" "" "\n" "\n",userName,pwd ]; NSLog(soapMessage); NSURL *url = [NSURL URLWithString:@"http://www.XXXXXXXXX.com/service.asmx"]; NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url]; NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]]; [theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"]; [theRequest addValue: @"http://XXXXXXXXm/Login" forHTTPHeaderField:@"SOAPAction"]; [theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"]; [theRequest setHTTPMethod:@"POST"]; [theRequest setHTTPBody: [soapMessage dataUsingEncoding:NSUTF8StringEncoding]]; NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; if( theConnection ) { webData = [[NSMutableData data] retain]; } else { NSLog(@"theConnection is NULL"); } //[nameInput resignFirstResponder]; return ResultString; } -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { [webData setLength: 0]; } -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [webData appendData:data]; } -(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { NSLog(@"ERROR with theConenction"); [connection release]; [webData release]; } -(void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"DONE. Received Bytes: %d", [webData length]); NSString *theXML = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding]; NSLog(theXML); [theXML release]; if( xmlParser ) { [xmlParser release]; } xmlParser = [[NSXMLParser alloc] initWithData: webData]; [xmlParser setDelegate: self]; [xmlParser setShouldResolveExternalEntities: YES]; [xmlParser parse]; [connection release]; [webData release]; } -(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *) namespaceURI qualifiedName:(NSString *)qName attributes: (NSDictionary *)attributeDict { if( [elementName isEqualToString:@"LoginResult"]) { if(!soapResults) { soapResults = [[NSMutableString alloc] init]; } recordResults = TRUE; } } -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { if( recordResults ) { [soapResults appendString: string]; } } -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { if( [elementName isEqualToString:@"LoginResult"]) { recordResults = FALSE; ResultString = soapResults; NSLog(@"Login"); [VariableStore setStr:ResultString]; NSLog(soapResults); [soapResults release]; soapResults = nil; } } @end I am calling LoginCheck method and based on result I want to show the second view. Here after finishing of the button touch down event, it enter into did end element, so I am always getting nil value. If I use the same code controller it works fine as I push second view controller in didendelement. Please give me some samples to place the web service calls in differnt class and how to call them in viewcontrollers. Regards, Malleswar

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• Updating D3 column chart with different values and different data sizes

  - by mbeasley

  Background I am attempting to create a reusable chart object with D3.js. I have setup a chart() function that will produce a column chart. On a click event on any of the columns, the chart will update with a new random data array that will contain a random number of data points (i.e. the original chart could have 8 columns, but upon update, could have 20 columns or 4 columns). Problem Say I have 8 data points (and thus 8 columns) in my original dataset. When I update the chart with random data, the columns appropriately adjust their height to the new values - but new bars aren't added. Additionally, while the width of the columns appropriately adjust to accommodate the width of the container and the new number of data points, if that number of data points is less than the original set, then some of those columns from the original dataset will linger until the number of data points is greater than or equal than the original. My end goal is to have new data dynamically added or old data outside of the range of the new data count dynamically removed. I've created a jsfiddle of the behavior. You may have to click the columns a couple of times to see the behavior I'm describing. Additionally, I've pasted my code below. Thanks in advance! function chart(config) { // set default options var defaultOptions = { selector: '#chartZone', class: 'chart', id: null, data: [1,2,6,4, 2, 6, 7, 2], type: 'column', width: 200, height: 200, callback: null, interpolate: 'monotone' }; // fill in unspecified settings in the config with the defaults var settings = $.extend(defaultOptions, config); function my() { // generate chart with this function var w = settings.width, h = settings.height, barPadding = 3, scale = 10, max = d3.max(settings.data); var svg = d3.select(settings.selector) // create the main svg container .append("svg") .attr("width",w) .attr("height",h); var y = d3.scale.linear().range([h, 0]), yAxis = d3.svg.axis().scale(y).ticks(5).orient("left"), x = d3.scale.linear().range([w, 0]); y.domain([0, max]).nice(); x.domain([0, settings.data.length - 1]).nice(); var rect = svg.selectAll("rect") .data(settings.data) .enter() .append("rect") .attr("x", function(d,i) { return i * (w / settings.data.length); }) .attr("y", function(d) { return h - h * (d / max); }) .attr("width", w / settings.data.length - barPadding) .attr("height", function(d) { return h * (d / max); }) .attr("fill", "rgb(90,90,90)"); svg.append("svg:g") .attr("class", "y axis") .attr("transform", "translate(-4,0)") .call(yAxis); svg.on("click", function() { var newData = [], maxCap = Math.round(Math.random() * 100); for (var i = 0; i < Math.round(Math.random()*100); i++) { var newNumber = Math.random() * maxCap; newData.push(Math.round(newNumber)); } newMax = d3.max(newData); y.domain([0, newMax]).nice(); var t = svg.transition().duration(750); t.select(".y.axis").call(yAxis); rect.data(newData) .transition().duration(750) .attr("height", function(d) { return h * (d / newMax); }) .attr("x", function(d,i) { return i * (w / newData.length); }) .attr("width", w / newData.length - barPadding) .attr("y", function(d) { return h - h * (d / newMax); }); }); } my(); return my; } var myChart = chart();

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• No data when attempting to get JSONP data from cross domain PHP script

  - by Alex

  I am trying to pull latitude and longitude values from another server on a different domain using a singe id string. I am not very familiar with JQuery, but it seems to be the easiest way to go about getting around the same origin problem. I am unable to use iframes and I cannot install PHP on the server running this javascript, which is forcing my hand on this. My queries appear to be going through properly, but I am not getting any results back. I was hoping someone here might have an idea that could help, seeing as I probably wouldn't recognize most obvious errors here. My javascript function is: var surl = "http://...omitted.../pull.php"; var idnum = 5a; //in practice this is defined above alert("BEFORE"); $.ajax({ url: surl, data: {id: idnum}, dataType: "jsonp", jsonp : "callback", jsonp: "jsonpcallback", success: function (rdata) { alert(rdata.lat + ", " + rdata.lon); } }); alert("BETWEEN"); function jsonpcallback(rtndata) { alert("CALLED"); alert(rtndata.lat + ", " + rtndata.lon); } alert("AFTER"); When my javascript is run, the BEFORE, BETWEEN and AFTER alerts are displayed. The CALLED and other jsonpcallback alerts are not shown. Is there another way to tell if the jsoncallback function has been called? Below is the PHP code I have running on the second server. I added the count table to my database just so that I can tell when this script is run. Every time I call the javascript, count has had an extra item inserted and the id number is correct. <?php header("content-type: application/json"); if (isset($_GET['id']) || isset($_POST['id'])){ $db_handle = mysql_connect($server, $username, $password); if (!$db_handle) { die('Could not connect: ' . mysql_error()); } $db_found = mysql_select_db($database, $db_handle); if ($db_found) { if (isset($_POST['id'])){ $SQL = sprintf("SELECT * FROM %s WHERE loc_id='%s'", $loctable, mysql_real_escape_string($_POST['id'])); } if (isset($_GET['id'])){ $SQL = sprintf("SELECT * FROM %s WHERE loc_id='%s'", $loctable, mysql_real_escape_string($_GET['id'])); } $result = mysql_query($SQL, $db_handle); $db_field = mysql_fetch_assoc($result); $rtnjsonobj -> lat = $db_field["lat"]; $rtnjsonobj -> lon = $db_field["lon"]; if (isset($_POST['id'])){ echo $_POST['jsonpcallback']. '('. json_encode($rtnjsonobj) . ')'; } if (isset($_GET['id'])){ echo $_GET['jsonpcallback']. '('. json_encode($rtnjsonobj) . ')'; } $SQL = sprintf("INSERT INTO count (bullshit) VALUES ('%s')", $_GET['id']); $result = mysql_query($SQL, $db_handle); $db_field = mysql_fetch_assoc($result); } mysql_close($db_handle); } else { $rtnjsonobj -> lat = 404; $rtnjsonobj -> lon = 404; echo $_GET['jsonpcallback']. '('. json_encode($rtnjsonobj) . ')'; }?> I am not entirely sure if the jsonp returned by this PHP is correct. When I go directly to the PHP script without including any parameters, I do get the following. ({"lat":404,"lon":404}) The callback function is not included, but that much can be expected when it isn't included in the original call. Does anyone have any idea what might be going wrong here? Thanks in advance!

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• Magento Onepage Success Conversion Tracking Design Pattern

  - by user1734954

  My intent is to track conversions through multiple channels by inserting third party javascript (for example google analytics, optimizely, pricegrabber etc.) into the footer of onepage success . I've accomplished this by adding a block to the footer reference inside of the checkout success node within local.xml and everything works appropriately. My questions are more about efficiency and extensibility. It occurred to me that it would be better to combine all of the blocks into a single block reference and then use a various methods acting on a single call to the various related models to provide the data needed for insertion into the javascript for each of the conversion tracking scripts. Some examples of the common data that conversion tracking may rely on(pseudo): Order ID , Order Total, Order.LineItem.Name(foreach) and so on Currently for each of the scripts I've made a call to the appropriate model passing the customers last order id as the load value and the calling a get() assigning the return value to a variable and then iterating through the data to match the values with the expectations of the given third party service. All of the data should be pulled once when checkout is complete each third party services may expect different data in different formats Here is an example of one of the conversion tracking template files which loads at the footer of checkout success. $order = Mage::getModel('sales/order')->loadByIncrementId(Mage::getSingleton('checkout/session')->getLastRealOrderId()); $amount = number_format($order->getGrandTotal(),2); $customer = Mage::helper('customer')->getCustomer()->getData(); ?> <script type="text/javascript"> popup_email = '<?php echo($customer['email']);?>'; popup_order_number = '<?php echo $this->getOrderId() ?>'; </script> <!-- PriceGrabber Merchant Evaluation Code --> <script type="text/javascript" charset="UTF-8" src="https://www.pricegrabber.com/rating_merchrevpopjs.php?retid=<something>"></script> <noscript><a href="http://www.pricegrabber.com/rating_merchrev.php?retid=<something>" target=_blank> <img src="https://images.pricegrabber.com/images/mr_noprize.jpg" border="0" width="272" height="238" alt="Merchant Evaluation"></a></noscript> <!-- End PriceGrabber Code --> Having just a single piece of code like this is not that big of a deal, but we are doing similar things with a number of different third party services. Pricegrabber is one of the simpler examples. A more sophisticated tracking service expects a comma separated list of all of the product names, ids, prices, categories , order id etc. I would like to make it all more manageable so my idea to do the following: combine all of the template files into a single file Develop a helper class or library to deliver the data to the conversion template Goals Include Extensibility Minimal Model Calls Minimal Method Calls The Questions 1. Is a Mage helper the best route to take? 2. Is there any design pattern you may recommend for the "helper" class? 3. Why would this the design pattern you've chosen be best for this instance?

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• Looking for best practise for writing a serial device communication app

  - by cdotlister

  I am pretty new to serial comms, but would like advise on how to best achieve a robust application which speak to and listens to a serial device. I have managed to make use of System.IO.SerialPort, and successfully connected to, sent data to and recieved from my device. The way things work is this. My application connects to the Com Port and opens the port.... I then connect my device to the com port, and it detects a connection to the PC, so sends a bit of text. it's really just copyright info, as well as the version of the firmware. I don't do anything with that, except display it in my 'activity' window. The device then waits. I can then query information, but sending a command such as 'QUERY PARAMETER1'. It then replies with something like: 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n' I then process that. I can then update it by sending 'SET PARAMETER1 12345', and it will reply with 'QUERY PARAMETER1\r\n\r\n12345\r\n\r\n'. All pretty basic. So, what I have done is created a Communication Class. this call is called in it's own thread, and sends data back to the main form... and also allows me to send messages to it. Sending data is easy. Recieving is a bit more tricky. I have employed the use of the datarecieved event, and when ever data comes in, I echo that to my screen. My problem is this: When I send a command, I feel I am being very dodgy in my handling. What I am doing is, lets say I am sending 'QUERY PARAMETER1'. I send the command to the device, I then put 'PARAMETER1' into a global variable, and I do a Thread.Sleep(100). On the data received, I then have a bit of logic that checks the incoming data, and sees if the string CONTAINS the value in the global variable. As the reply may be 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n', it sees that it contains my parameter, parses the string, and returns the value I am looking for, but placing it into another global variable. My sending method was sleeping for 100ms. It then wakes, and checks the returned global variable. If it has data... then I'm happy, and I process the data. Problem is... if the sleep is too short.. it will fail. And I feel it's flaky.. putting stuff into variables.. then waiting... The other option is to use ReadLine instead, but that's very blocking. So I remove the data received method, and instead... just send the data... then call ReadLine(). That may give me better results. There's no time, except when we connect initially, that data comes from the device, without me requesting it. So, maybe ReadLine will be simpler and safer? Is this known as 'Blocking' reads? Also, can I set a timeout? Hopefully someone can guide me.

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• Help in building an 16 bit os

  - by Barshan Das

  I am trying to build an old 16 bit dos like os. My bootloader code: ; This is not my code. May be of Fritzos. I forgot the source. ORG 7c00h jmp Start drive db 0 msg db " Loader Initialization",0 msg2 db "ACos Loaded",0 print: lodsb cmp al, 0 je end mov ah, 0Eh int 10h jmp print end: ret Start: mov [ drive ], dl ; Get the floppy OS booted from ; Update the segment registers xor ax, ax ; XOR ax mov ds, ax ; Mov AX into DS mov si,msg call print ; Load Kernel. ResetFloppy: mov ax, 0x00 ; Select Floppy Reset BIOS Function mov dl, [ drive ] ; Select the floppy ADos booted from int 13h ; Reset the floppy drive jc ResetFloppy ; If there was a error, try again. ReadFloppy: mov bx, 0x9000 ; Load kernel at 9000h. mov ah, 0x02 ; Load disk data to ES:BX mov al, 17 ; Load two floppy head full's worth of data. mov ch, 0 ; First Cylinder mov cl, 2 ; Start at the 2nd Sector to load the Kernel mov dh, 0 ; Use first floppy head mov dl, [ drive ] ; Load from the drive kernel booted from. int 13h ; Read the floppy disk. jc ReadFloppy ; Error, try again. ; Clear text mode screen mov ax, 3 int 10h ;print starting message mov si,msg2 call print mov ax, 0x0 mov ss, ax mov sp, 0xFFFF jmp 9000h ; This part makes sure the bootsector is 512 bytes. times 510-($-$$) db 0 ;bootable sector signature dw 0xAA55 My example kernel code: asm(".code16\n"); void putchar(char); int main() { putchar('A'); return 0; } void putchar(char val) { asm("movb %0, %%al\n" "movb $0x0E, %%ah\n" "int $0x10\n" : :"r"(val) ) ; } This is how I compile it : nasm -f bin -o ./bin/boot.bin ./source/boot.asm gcc -nostdinc -fno-builtin -I./include -c -o ./bin/kernel.o ./source/kernel.c ld -Ttext=0x9000 -o ./bin/kernel.bin ./bin/kernel.o -e 0x0 dd if=/dev/zero of=./bin/empty.bin bs=1440K count=1 cat ./bin/boot.bin ./bin/kernel.bin ./bin/empty.bin|head -c 1440K > ./bin/os rm ./bin/empty.bin and I run it in virtual machine. When I make the putchar function ( in kernel code ) for constant value ....i.e like this: void putchar() { char val = 'A'; asm("movb %0, %%al\n" "movb $0x0E, %%ah\n" "int $0x10\n" : :"r"(val) ) ; } then it works fine. But when I pass argument to it ( That is in the previous code ) , then it prints a space for any character. What should I do?

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• BFS Shortest Path: Edge weight either 1 or 2

  - by Hackster

  I am trying to implement a shortest path algorithm using BFS. That is I am trying to find the shortest path from a specified vertex to every other vertex. However, its a special case where all edge weights are either 1 or 2. I know it could be done with Dijkstra's algorithm but I must use Breadth First Search. So far I have a working version of BFS that searches first for a vertex connected with an edge of weight 1. If it cannot find it, then returns a vertex connected with an edge of weight 2. After thinking about it, this is not the correct way to find the shortest path. The problem is I cannot think of any reasoning why BFS would work with weights 1 or 2, as opposed to any weight. Here is the code: public void addEdge(int start, int end, int weight) { adjMat[start][end] = 1; adjMat[end][start] = 1; edge_weight[start][end] = weight; edge_weight[end][start] = weight; } // ------------------------------------------------------------- public void bfs() // breadth-first search { // begin at vertex 0 vertexList[0].wasVisited = true; // mark it displayVertex(0); // display it theQueue.insert(0); // insert at tail int v2; while( !theQueue.isEmpty() ) // until queue empty, { int v1 = theQueue.remove(); // remove vertex at head // until it has no unvisited neighbors while( (v2=getAdjUnvisitedVertex(v1)) != -1 ){// get one, vertexList[v2].wasVisited = true; // mark it displayVertex(v2); // display it theQueue.insert(v2); // insert it } } // end while(queue not empty) // queue is empty, so we're done for(int j=0; j<nVerts; j++) // reset flags vertexList[j].wasVisited = false; } // end bfs() // ------------------------------------------------------------- // returns an unvisited vertex adj to v -- ****WITH WEIGHT 1**** public int getAdjUnvisitedVertex(int v) { for (int j = 0; j < nVerts; j++) if (adjMat[v][j] == 1 && vertexList[j].wasVisited == false && edge_weight[v][j] == 1){ //System.out.println("Vertex found with 1:"+ vertexList[j].label); return j; } for (int k = 0; k < nVerts; k++) if (adjMat[v][k] == 1 && vertexList[k].wasVisited == false && edge_weight[v][k] == 2){ //System.out.println("Vertex found with 2:"+vertexList[k].label); return k; } return -1; } // end getAdjUnvisitedVertex() // ------------------------------------------------------------- } //////////////////////////////////////////////////////////////// public class BFS{ public static void main(String[] args) { Graph theGraph = new Graph(); theGraph.addVertex('A'); // 0 (start for bfs) theGraph.addVertex('B'); // 1 theGraph.addVertex('C'); // 2 theGraph.addEdge(0, 1,2); // AB theGraph.addEdge(1, 2,1); // BC theGraph.addEdge(2, 0,1); // AD System.out.print("Visits: "); theGraph.bfs(); // breadth-first search System.out.println(); } // end main() } The problem then is, that I don't know why BFS can work for the shortest path problem with edges of weight 1 or 2 as opposed to any edges of any weight. Any help is appreciated. Thanks!

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• ANT: ways to include libraries and license issues

  - by Eric Tobias

  I have been trying to use Ant to compile and ready a project for distribution. I have encountered several problems along the way that I have been finally able to solve but the solution leaves me very unsatisfied. First, let me explain the set-up of the project and its dependencies. I have a project, lets call it Primary which depends on a couple of libraries such as the fantastic Guava. It also depends on another project of mine, lets call it Secondary. The Secondary project also features some dependencies, for example, JDOM2. I have referenced the Jar I build with Ant in Primary. Let me give you the interesting bits of the build.xml so you can get a picture of what I am doing: <project name="Primary" default="all" basedir="."> <property name='build' location='dist' /> <property name='application.version' value='1.0'/> <property name='application.name' value='Primary'/> <property name='distribution' value='${application.name}-${application.version}'/> <path id='compile.classpath'> <fileset dir='libs'> <include name='*.jar'/> </fileset> </path> <target name='compile' description='Compile source files.'> <javac includeantruntime="false" srcdir="src" destdir="bin"> <classpath refid='compile.classpath'/> </javac> <target> <target name='jar' description='Create a jar file for distribution.' depends="compile"> <jar destfile='${build}/${distribution}.jar'> <fileset dir="bin"/> <zipgroupfileset dir="libs" includes="*.jar"/> </jar> </target> The Secodnary project's build.xml is nearly identical except that it features a manifest as it needs to run: <target name='jar' description='Create a jar file for distribution.' depends="compile"> <jar destfile='${dist}/${distribution}.jar' basedir="${build}" > <fileset dir="${build}"/> <zipgroupfileset dir="libs" includes="*.jar"/> <manifest> <attribute name="Main-Class" value="lu.tudor.ssi.kiss.climate.ClimateChange"/> </manifest> </jar> </target> After I got it working, trying for many hours to not include that dependencies as class files but as Jars, I don't have the time or insight to go back and try to figure out what I did wrong. Furthermore, I believe that including these libraries as class files is bad practice as it could give rise to licensing issues while not packaging them and merely including them in a directory along the build Jar would most probably not (And if it would you could choose not to distribute them yourself). I think my inability to correctly assemble the class path, I always received NoClassDefFoundError for classes or libraries in the Primary project when launching Second's Jar, is that I am not very experienced with Ant. Would I require to specify a class path for both projects? Specifying the class path as . should have allowed me to simply add all dependencies to the same folder as Secondary's Jar, should it not?

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• WCF service is not getting called

  - by Cheranga

  I have a web solution and I have a WCF service project inside it. We need to support "cookieless". so in the web.config, it's set as <sessionState mode="SQLServer" sqlConnectionString="Data Source=ds;Initial Catalog=db;User Id=uid;Password=pwd" allowCustomSqlDatabase="true" cookieless="true" timeout="720" regenerateExpiredSessionId="false"/> The WCF service will be supporting sessions, so we have also set "aspNetCompatibilityEnabled" to true in web.config. <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true"/> The service and interfaces are as follows, [ServiceContract(SessionMode=SessionMode.Allowed)] public interface ICDOCService { } [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class CDOCService : ICDOCService { } The problem we are facing is we cannot access the service from any client application. (web app, WCF test client) The following error is showing, when we access it via WCF Test client, Failed to invoke the service. Possible causes: The service is offline or inaccessible; the client-side configuration does not match the proxy; the existing proxy is invalid. Refer to the stack trace for more detail. You can try to recover by starting a new proxy, restoring to default configuration, or refreshing the service. The content type text/html; charset=UTF-8 of the response message does not match the content type of the binding (multipart/related; type="application/xop+xml"). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly. The first 1024 bytes of the response were: <HTML> <HEAD> <link rel="alternate" type="text/xml" href="http://localhost:53721/Services/CDOCService.svc?disco"/> <STYLE type="text/css">#content{ FONT-SIZE: 0.7em; PADDING-BOTTOM: 2em; MARGIN-LEFT: 30px}BODY{MARGIN-TOP: 0px; MARGIN-LEFT: 0px; COLOR: #000000; FONT-FAMILY: Verdana; BACKGROUND-COLOR: white}P{MARGIN-TOP: 0px; MARGIN-BOTTOM: 12px; COLOR: #000000; FONT-FAMILY: Verdana}PRE{BORDER-RIGHT: #f0f0e0 1px solid; PADDING-RIGHT: 5px; BORDER-TOP: #f0f0e0 1px solid; MARGIN-TOP: -5px; PADDING-LEFT: 5px; FONT-SIZE: 1.2em; PADDING-BOTTOM: 5px; BORDER-LEFT: #f0f0e0 1px solid; PADDING-TOP: 5px; BORDER-BOTTOM: #f0f0e0 1px solid; FONT-FAMILY: Courier New; BACKGROUND-COLOR: #e5e5cc}.heading1{MARGIN-TOP: 0px; PADDING-LEFT: 15px; FONT-WEIGHT: normal; FONT-SIZE: 26px; MARGIN-BOTTOM: 0px; PADDING-BOTTOM: 3px; MARGIN-LEFT: -30px; WIDTH: 100%; COLOR: #ffffff; PADDING-TOP: 10px; FONT-FAMILY: Tahoma; BACKGROUND-COLOR: #003366}.intro{MARGIN-LEFT: -15px} </STYLE> <TITLE>CDOCService Service</TITLE></HEAD><BODY><DIV id="content"><P '. Server stack trace: at System.ServiceModel.Channels.HttpChannelUtilities.ValidateRequestReplyResponse(HttpWebRequest request, HttpWebResponse response, HttpChannelFactory factory, WebException responseException, ChannelBinding channelBinding) at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout) at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout) at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout) at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout) at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs) at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation) at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message) Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at ICDOCService.GetCDOCCount(String institutionID, String mrnID, String userID, String callingSystemID, String securityToken) at CDOCServiceClient.GetCDOCCount(String institutionID, String mrnID, String userID, String callingSystemID, String securityToken)

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• Chinese Characters in email sent via PHP not showing up.

  - by rye

  hi All, a funny problem. I send mail via PHP from my testing server with Chinese chars in it and it sends perfectly. Encoding is utf-8. When I upload the same PHP file to another server and try to send from there, the e-mail will look 90% fine in one mail client (web-based mail actually, gmail), but in my mail client (Apple Mail) it's all gibberish even when I try changing the encoding in the mail client. I'm stuck here because everything works fine on one server, but not on another so I'm not sure where to start looking for solutions. What's even more puzzling is that on the production server, the mail looks somewhat ok (strange case of some characters not showing) but in other mail apps it looks like garbage. any idea where I can start looking to solve this? thanks for any help here! Regards.. php script $books = json_decode ($_POST['books']); $body = ' ?? ' . $_POST['name'] . ',?????????,????????,???????? '; $iLen = count($books); for ($i = 0; $i ' . $book-title . '' . $book-author . ''; $body .= '??: ' . $book-synopsis . ''; $body .= '???: ' . $book-age . ''; $body .= '??: ' . $book-setting . ''; $body .= '??: ' . $book-purpose . ''; $body .= '???: ' . $book-call . ''; $body .= '???: ' . $book-publisher . ''; } $body .= ' ????,Name '; $headers = 'MIME-Version: 1.0' . "\r\n"; $headers .= 'Content-type: text/html; charset=utf-8' . "\r\n"; $headers .= 'From: Name ' . "\r\n"; $ok = mail ($_POST['email'], '???????:???????????', $body, $headers); result ä? å¥? ryan, 以丗æ?¯ä? ä»/å–œä’ ç?Œç«?,ç»?å–©å–?è®”æ??亗è¯=稗,昕蜙æ±?ç°=䒜籟å?ŸåŸ? ç‘?ç‘?ævŒæ?˜å¤°çv±ä? 麜å?—å¸8é?·å°p, å±±å§? Synopsis: ç?—å?¯çv±ç°=å°?å?‰å®?å®?æ•/ä’v牨å®8痬瘒ç°=戒åp?å‚‘å?‰åœvåœv说å®8æ?˜å¤°çv±å®8ã•? Age Group: 4 - 6 å”™ Setting: ç=¤ä?„ Purpose: ä»·å•pè§?å‚‘ä¿8è¿?五å–?ç°=æ=ƒæ8? Call no: JP MAC Publisher: 麜å?—å¸8é?·å°p, å±±å§?. ç‘?ç‘?ævŒæ?˜å¤°çv±ä? .丅海 : 尌咴å=¿ç«¥åOºç˜vç¤=, 2005.

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• How can I determine/use $(this) in js callback script

  - by Rabbott

  I am using Rails and jQuery, making an ajax call initiated by clicking a link. I setup my application.js file to look like the one proposed here and it works great. The problem I'm having is how can I use $(this) in my say.. update.js.erb file to represent the link I clicked? I don't want to have to assign an ID to every one, then recompile that id in the callback script.. EDIT To give a simple example of something similar to what I'm trying to do (and much easier to explain): If a user clicks on a link, that deletes that element from a list, the controller would handle the callback, and the callback (which is in question here) would delete the element I clicked on, so in the callback delete.js.erb would just say $(this).fadeOut(); This is why I want to use $(this) so that I dont have to assign an ID to every element (which would be the end of the world, just more verbose markup) application.js jQuery.ajaxSetup({ 'beforeSend': function(xhr) {xhr.setRequestHeader("Accept", "text/javascript,application/javascript,text/html")} }) function _ajax_request(url, data, callback, type, method) { if (jQuery.isFunction(data)) { callback = data; data = {}; } return jQuery.ajax({ type: method, url: url, data: data, success: callback, dataType: type }); } jQuery.extend({ put: function(url, data, callback, type) { return _ajax_request(url, data, callback, type, 'PUT'); }, delete_: function(url, data, callback, type) { return _ajax_request(url, data, callback, type, 'DELETE'); } }); jQuery.fn.submitWithAjax = function() { this.unbind('submit', false); this.submit(function() { $.post(this.action, $(this).serialize(), null, "script"); return false; }) return this; }; // Send data via get if <acronym title="JavaScript">JS</acronym> enabled jQuery.fn.getWithAjax = function() { this.unbind('click', false); this.click(function() { $.get($(this).attr("href"), $(this).serialize(), null, "script"); return false; }) return this; }; // Send data via Post if <acronym title="JavaScript">JS</acronym> enabled jQuery.fn.postWithAjax = function() { this.unbind('click', false); this.click(function() { $.post($(this).attr("href"), $(this).serialize(), null, "script"); return false; }) return this; }; jQuery.fn.putWithAjax = function() { this.unbind('click', false); this.click(function() { $.put($(this).attr("href"), $(this).serialize(), null, "script"); return false; }) return this; }; jQuery.fn.deleteWithAjax = function() { this.removeAttr('onclick'); this.unbind('click', false); this.click(function() { $.delete_($(this).attr("href"), $(this).serialize(), null, "script"); return false; }) return this; }; // This will "ajaxify" the links function ajaxLinks(){ $('.ajaxForm').submitWithAjax(); $('a.get').getWithAjax(); $('a.post').postWithAjax(); $('a.put').putWithAjax(); $('a.delete').deleteWithAjax(); } show.html.erb <%= link_to 'Link Title', article_path(a, :sentiment => Article::Sentiment['Neutral']), :class => 'put' %> The combination of the two things will call update.js.erb in rails, the code in that file is used as the callback of the ajax ($.put in this case) update.js.erb // user feedback $("#notice").html('<%= flash[:notice] %>'); // update the background color $(this OR e.target).attr("color", "red");

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• hosting simple python scripts in a container to handle concurrency, configuration, caching, etc.

  - by Justin Grant

  My first real-world Python project is to write a simple framework (or re-use/adapt an existing one) which can wrap small python scripts (which are used to gather custom data for a monitoring tool) with a "container" to handle boilerplate tasks like: fetching a script's configuration from a file (and keeping that info up to date if the file changes and handle decryption of sensitive config data) running multiple instances of the same script in different threads instead of spinning up a new process for each one expose an API for caching expensive data and storing persistent state from one script invocation to the next Today, script authors must handle the issues above, which usually means that most script authors don't handle them correctly, causing bugs and performance problems. In addition to avoiding bugs, we want a solution which lowers the bar to create and maintain scripts, especially given that many script authors may not be trained programmers. Below are examples of the API I've been thinking of, and which I'm looking to get your feedback about. A scripter would need to build a single method which takes (as input) the configuration that the script needs to do its job, and either returns a python object or calls a method to stream back data in chunks. Optionally, a scripter could supply methods to handle startup and/or shutdown tasks. HTTP-fetching script example (in pseudocode, omitting the actual data-fetching details to focus on the container's API): def run (config, context, cache) : results = http_library_call (config.url, config.http_method, config.username, config.password, ...) return { html : results.html, status_code : results.status, headers : results.response_headers } def init(config, context, cache) : config.max_threads = 20 # up to 20 URLs at one time (per process) config.max_processes = 3 # launch up to 3 concurrent processes config.keepalive = 1200 # keep process alive for 10 mins without another call config.process_recycle.requests = 1000 # restart the process every 1000 requests (to avoid leaks) config.kill_timeout = 600 # kill the process if any call lasts longer than 10 minutes Database-data fetching script example might look like this (in pseudocode): def run (config, context, cache) : expensive = context.cache["something_expensive"] for record in db_library_call (expensive, context.checkpoint, config.connection_string) : context.log (record, "logDate") # log all properties, optionally specify name of timestamp property last_date = record["logDate"] context.checkpoint = last_date # persistent checkpoint, used next time through def init(config, context, cache) : cache["something_expensive"] = get_expensive_thing() def shutdown(config, context, cache) : expensive = cache["something_expensive"] expensive.release_me() Is this API appropriately "pythonic", or are there things I should do to make this more natural to the Python scripter? (I'm more familiar with building C++/C#/Java APIs so I suspect I'm missing useful Python idioms.) Specific questions: is it natural to pass a "config" object into a method and ask the callee to set various configuration options? Or is there another preferred way to do this? when a callee needs to stream data back to its caller, is a method like context.log() (see above) appropriate, or should I be using yield instead? (yeild seems natural, but I worry it'd be over the head of most scripters) My approach requires scripts to define functions with predefined names (e.g. "run", "init", "shutdown"). Is this a good way to do it? If not, what other mechanism would be more natural? I'm passing the same config, context, cache parameters into every method. Would it be better to use a single "context" parameter instead? Would it be better to use global variables instead? Finally, are there existing libraries you'd recommend to make this kind of simple "script-running container" easier to write?

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• Launching an Activity from a Service

  - by nldev

  When I am trying to launch a call activity from a Service, I get a NullPointerException. Here is my code: Intent callIntent = new Intent(Intent.ACTION_CALL); callIntent.setData(Uri.parse("tel:" + number)); callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); startActivity(callIntent); I get the exception on the startActivity line. I tried to use getApplication.startActivity and getApplicationContext.startActivity but no luck. Any ideas? edit : Maybe some usefull info: I am trying to create a service that will run on the background and scan sensor data, when a certain signal is given i would like to maken an automated call to a number. edit : full adb error code: 03-31 09:04:10.214: ERROR/AndroidRuntime(1896): Uncaught handler: thread main exiting due to uncaught exception 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): java.lang.RuntimeException: Unable to instantiate service dfz.epilepsiedetector.services.DetectionService: java.lang.NullPointerException 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2668) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.app.ActivityThread.access$3100(ActivityThread.java:116) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1846) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.os.Handler.dispatchMessage(Handler.java:99) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.os.Looper.loop(Looper.java:123) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.app.ActivityThread.main(ActivityThread.java:4203) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at java.lang.reflect.Method.invokeNative(Native Method) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at java.lang.reflect.Method.invoke(Method.java:521) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at dalvik.system.NativeStart.main(Native Method) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): Caused by: java.lang.NullPointerException 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.content.ContextWrapper.getPackageName(ContextWrapper.java:120) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.content.ComponentName.<init>(ComponentName.java:75) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.content.Intent.<init>(Intent.java:2302) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at dfz.epilepsiedetector.services.DetectionService.<init>(DetectionService.java:35) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at java.lang.Class.newInstanceImpl(Native Method) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at java.lang.Class.newInstance(Class.java:1472) 03-31 09:04:10.226: ERROR/AndroidRuntime(1896): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2665) edit Trimmed class code: `public class DetectionService extends IntentService implements SensorEventListener { private SensorManager mSensorManager; private Sensor mAccelerometer; private boolean hasSeizure = false; private final int POLLS_PER_SECOND = 10; public DetectionService() { super("EpilepsionDetectionService"); //mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); // mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); /*Intent callIntent = new Intent(Intent.ACTION_CALL); callIntent.setData(Uri.parse("tel:" + "+31648363944")); callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);*/ Intent callIntent = new Intent(DetectionService.this, InformationActivity.class); callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); getApplication().startActivity(callIntent); //((Activity) getContext()).startActivity(callIntent); }`

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• MVC multi page form losing session

  - by Bryan

  I have a multi-page form that's used to collect leads. There are multiple versions of the same form that we call campaigns. Some campaigns are 3 page forms, others are 2 pages, some are 1 page. They all share the same lead model and campaign controller, etc. There is 1 action for controlling the flow of the campaigns, and a separate action for submitting all the lead information into the database. I cannot reproduce this locally, and there are checks in place to ensure users can't skip pages. Session mode is InProc. This runs after every POST action which stores the values in session: protected override void OnActionExecuted(ActionExecutedContext filterContext) { base.OnActionExecuted(filterContext); if (this.Request.RequestType == System.Net.WebRequestMethods.Http.Post && this._Lead != null) ParentStore.Lead = this._Lead; } This is the Lead property within the controller: private Lead _Lead; /// <summary> /// Gets the session stored Lead model. /// </summary> /// <value>The Lead model stored in session.</value> protected Lead Lead { get { if (this._Lead == null) this._Lead = ParentStore.Lead; return this._Lead; } } ParentStore class: public static class ParentStore { internal static Lead Lead { get { return SessionStore.Get<Lead>(Constants.Session.Lead, new Lead()); } set { SessionStore.Set(Constants.Session.Lead, value); } } Campaign POST action: [HttpPost] public virtual ActionResult Campaign(Lead lead, string campaign, int page) { if (this.Session.IsNewSession) return RedirectToAction("Campaign", new { campaign = campaign, page = 0 }); if (ModelState.IsValid == false) return View(GetCampaignView(campaign, page), this.Lead); TrackLead(this.Lead, campaign, page, LeadType.Shared); return RedirectToAction("Campaign", new { campaign = campaign, page = ++page }); } The problem is occuring between the above action, and before the following Submit action executes: [HttpPost] public virtual ActionResult Submit(Lead lead, string campaign, int page) { if (this.Session.IsNewSession || this.Lead.Submitted || !this.LeadExists) return RedirectToAction("Campaign", new { campaign = campaign, page = 0 }); lead.AddCustomQuestions(); MergeLead(campaign, lead, this.AdditionalQuestionsType, false); if (ModelState.IsValid == false) return View(GetCampaignView(campaign, page), this.Lead); var sharedLead = this.Lead.ToSharedLead(Request.Form.ToQueryString(false)); //Error occurs here and sends me an email with whatever values are in the form collection. EAUtility.ProcessLeadProxy.SubmitSharedLead(sharedLead); this.Lead.Submitted = true; VisitorTracker.DisplayConfirmationPixel = true; TrackLead(this.Lead, campaign, page, LeadType.Shared); return RedirectToAction(this.ConfirmationView); } Every visitor to our site gets a unique GUID visitorID. But when these error occurs there is a different visitorID between the Campaign POST and the Submit POST. Because we track each form submission via the TrackLead() method during campaign and submit actions I can see session is being lost between calls, despite the OnActionExecuted firing after every POST and storing the form in session. So when there are errors, we get half the form under one visitorID and the remainder of the form under a different visitorID. Luckily we use a third party service which sends an API call every time a form value changes which uses it's own ID. These IDs are consistent between the first half of the form, and the remainder of the form, and the only way I can save the leads from the lost session issues. I should also note that this works fine 99% of the time. EDIT: I've modified my code to explicitly store my lead object in TempData and used the TempData.Keep() method to persist the object between subsequent requests. I've only deployed this behavior to 1 of my 3 sites but so far so good. I had also tried storing my lead objects in Session directly in the controller action i.e., Session.Add("lead", this._Lead); which uses HTTPSessionStateBase, attempting to circumvent the wrapper class, instead of HttpContext.Current.Session which uses HTTPSessionState. This modification made no difference on the issue, as expected.

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• C++ Serial Port Question

  - by Pfeffer

  Problem: I have a hand held device that scans those graphic color barcodes on all packaging. There is a track device that I can use that will slide the device automatically. This track device functions by taking ascii code through a serial port. I need to get this thing to work in FileMaker on a Mac. So no terminal programs, etc... What I've got so far: I bought a Keyspan USB/Serial adapter. Using a program called ZTerm I was successful in sending commands to the device. Example: "C,7^M^J" I was also able to do the same thing in Terminal using this command: screen /dev/tty.KeySerial1 57600 and then type in the same command above(but when I typed in I just hit Control-M and Control-J for the carriage return and line feed) Now I'm writing a plug-in for FileMaker(in C++ of course). I want to get what I did above happen in C++ so when I install that plug-in in FileMaker I can just call one of those functions and have the whole process take place right there. I'm able to connect to the device, but I can't talk to it. It is not responding to anything. I've tried connecting to the device(successfully) using these: FILE *comport; if ((comport = fopen("/dev/tty.KeySerial1", "w")) == NULL){...} and int fd; fd = open("/dev/tty.KeySerial1", O_RDWR | O_NOCTTY | O_NDELAY); This is what I've tried so far in way of talking to the device: fputs ("C,7^M^J",comport); or fprintf(comport,"C,7^M^J"); or char buffer[] = { 'C' , ',' , '7' , '^' , 'M' , '^' , 'J' }; fwrite (buffer , 1 , sizeof(buffer) , comport ); or fwrite('C,7^M^J', 1, 1, comport); Questions: When I connected to the device from Terminal and using ZTerm, I was able to set my baud rate of 57600. I think that may be why it isn't responding here. But I don't know how to do it here.... Does any one know how to do that? I tried this, but it didn't work: comport->BaudRate = 57600; There are a lot of class solutions out there but they all call these include files like termios.h and stdio.h. I don't have these and, for whatever reason, I can't find them to download. I've downloaded a few examples but there are like 20 files in them and they're all calling other files I can't find(like the ones listed above). Do I need to find these and if so where? I just don't know enough about C++ Is there a website where I can download libraries?? Another solution might be to put those terminal commands in C++. Is there a way to do that? So this has been driving me crazy. I'm not a C++ guy, I only know basic programming concepts. Is anyone out there a C++ expert? I ideally I'd like this to just work using functions I already have, like those fwrite, fputs stuff. Thanks!

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• How to implement this .NET client and PHP server synchronization scenario?

  - by pbean

  I have a PHP webserver and a .NET mobile application. The .NET application needs data from a database, which is provided (for now) by the php webserver. I'm fairly new to this kind of scenario so I'm not sure what the best practices are. I ran into a couple of problems and I am not certain how to overcome them. For now, I have the following setup. I run a PHP SOAP server which has a couple of operations which simply retrieve data from the database. For this web service I have created a WSDL file. In Visual Studio I added a web reference to my project using the WSDL file and it generated some classes for it. I simply call something like "MyWebService.GetItems();" and I get an array of items in my .NET application, which come straight from the database. Next I also serialize all these retrieved objects to local (permanent) storage. I face a couple of challenges which I don't know how to resolve properly. The idea is for the mobile client to synchronize the data once (at the start of the day), before working, and then use the local storage throughout the day, and synchronize it back at the end of the day. At the moment all data is downloaded through SOAP, and not a subset (only what is needed). How would I know which new information should be sent to the client? Only the server knows what is new, but only the client knows for sure which data it already has. I seem to be doing double work now. The data which is transferred with SOAP basically already are serialized objects. But at the moment I first retrieve all objects through SOAP and the .NET framework automatically deserializes it. Then I serialize all data again myself. It would be more efficient to simply download it to storage, and then deserialize it. The mobile device does not have a lot of memory. In my test data this is not really a problem, but with potentially tenths of thousands of records I can imagine this will become a problem. Currently when I call the SOAP method, it loads all data into memory (as an array) but as described above perhaps it would be better to have it stored into storage directly, and only retrieve from storage the objects that are needed. But how would I store this? An array would serialize to one big XML (or binary) file from which I cannot choose which objects to load. Would I make (possible tenths of thousands) separate files? Also at the end of the day when I want to send the changes back to the server, how would I know which objects to send... since they're not in memory? I hope my troubles are clear and I hope you are able to help me figure out how to implement this the best way. :) Some things are already fixed (like using .NET on the mobile device, using PHP and having a MySQL database server) but other things can most certainly be changed (like using SOAP).

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• Templated function with two type parameters fails compile when used with an error-checking macro

  - by SirPentor

  Because someone in our group hates exceptions (let's not discuss that here), we tend to use error-checking macros in our C++ projects. I have encountered an odd compilation failure when using a templated function with two type parameters. There are a few errors (below), but I think the root cause is a warning: warning C4002: too many actual parameters for macro 'BOOL_CHECK_BOOL_RETURN' Probably best explained in code: #include "stdafx.h" template<class A, class B> bool DoubleTemplated(B & value) { return true; } template<class A> bool SingleTemplated(A & value) { return true; } bool NotTemplated(bool & value) { return true; } #define BOOL_CHECK_BOOL_RETURN(expr) \ do \ { \ bool __b = (expr); \ if (!__b) \ { \ return false; \ } \ } while (false) \ bool call() { bool thing = true; // BOOL_CHECK_BOOL_RETURN(DoubleTemplated<int, bool>(thing)); // Above line doesn't compile. BOOL_CHECK_BOOL_RETURN((DoubleTemplated<int, bool>(thing))); // Above line compiles just fine. bool temp = DoubleTemplated<int, bool>(thing); // Above line compiles just fine. BOOL_CHECK_BOOL_RETURN(SingleTemplated<bool>(thing)); BOOL_CHECK_BOOL_RETURN(NotTemplated(thing)); return true; } int _tmain(int argc, _TCHAR* argv[]) { call(); return 0; } Here are the errors, when the offending line is not commented out: 1>------ Build started: Project: test, Configuration: Debug Win32 ------ 1>Compiling... 1>test.cpp 1>c:\junk\temp\test\test\test.cpp(38) : warning C4002: too many actual parameters for macro 'BOOL_CHECK_BOOL_RETURN' 1>c:\junk\temp\test\test\test.cpp(38) : error C2143: syntax error : missing ',' before ')' 1>c:\junk\temp\test\test\test.cpp(38) : error C2143: syntax error : missing ';' before '{' 1>c:\junk\temp\test\test\test.cpp(41) : error C2143: syntax error : missing ';' before '{' 1>c:\junk\temp\test\test\test.cpp(48) : error C2143: syntax error : missing ';' before '{' 1>c:\junk\temp\test\test\test.cpp(49) : error C2143: syntax error : missing ';' before '{' 1>c:\junk\temp\test\test\test.cpp(52) : error C2143: syntax error : missing ';' before '}' 1>c:\junk\temp\test\test\test.cpp(54) : error C2065: 'argv' : undeclared identifier 1>c:\junk\temp\test\test\test.cpp(54) : error C2059: syntax error : ']' 1>c:\junk\temp\test\test\test.cpp(55) : error C2143: syntax error : missing ';' before '{' 1>c:\junk\temp\test\test\test.cpp(58) : error C2143: syntax error : missing ';' before '}' 1>c:\junk\temp\test\test\test.cpp(60) : error C2143: syntax error : missing ';' before '}' 1>c:\junk\temp\test\test\test.cpp(60) : fatal error C1004: unexpected end-of-file found 1>Build log was saved at "file://c:\junk\temp\test\test\Debug\BuildLog.htm" 1>test - 12 error(s), 1 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Any ideas? Thanks!

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• "FOR UPDATE" v/s "LOCK IN SHARE MODE" : Allow concurrent threads to read updated "state" value of locked row

  - by shadesco

  I have the following scenario: User X logs in to the application from location lc1: call it Ulc1 User X (has been hacked, or some friend of his knows his login credential, or he just logs in from a different browser on his machine,etc.. u got the point) logs in at the same time from location lc2: call it Ulc2 I am using a main servlet which : - gets a connection from database pooling - sets autocommit to false - executes a command that goes through app layers: if all successful, set autocommit to true in a "finally" statement, and closes connection. Else if an exception happens, rollback(). In my database (mysql/innoDb) i have a "history" table, with row columns: id(primary key) |username | date | topic | locked The column "locked" has by default value "false" and it serves as a flag that marks if a specific row is locked or not. Each row is specific to a user (as u can see from the username column) So back to the scenario: --Ulc1 sends the command to update his history from the db for date "D" and topic "T". --Ulc2 sends the same command to update history from the db for the same date "D" and same topic "T" at the exact same time. I want to implement an mysql/innoDB locking system that will enable whichever thread arriving to do the following check: Is column "locked" for this row true or not? if true, return a message to the user that " he is already updating the same data from another location" if not true (ie not locked) : flag it as locked and update then reset locked to false once finished. Which of these two mysql locking techniques, will actually allow the 2nd arriving thread from reading the "updated" value of the locked column to decide wt action to take?Should i use "FOR UPDATE" or "LOCK IN SHARE MODE"? This scenario explains what i want to accomplish: - Ulc1 thread arrives first: column "locked" is false, set it to true and continue updating process - Ulc2 thread arrives while Ulc1's transaction is still in process, and even though the row is locked through innoDb functionalities, it doesn't have to wait but in fact reads the "new" value of column locked which is "true", and so doesn't in fact have to wait till Ulc1 transaction commits to read the value of the "locked" column(anyway by that time the value of this column will already have been reset to false). I am not very experienced with the 2 types of locking mechanisms, what i understand so far is that LOCK IN SHARE MODE allow other transaction to read the locked row while FOR UPDATE doesn't even allow reading. But does this read gets on the updated value? or the 2nd arriving thread has to wait the first thread to commit to then read the value? Any recommendations about which locking mechanism to use for this scenario is appreciated. Also if there's a better way to "check" if the row has been locked (other than using a true/false column flag) please let me know about it. thank you SOLUTION (Jdbc pseudocode example based on @Darhazer's answer) Table : [ id(primary key) |username | date | topic | locked ] connection.setautocommit(false); //transaction-1 PreparedStatement ps1 = "Select locked from tableName for update where id="key" and locked=false); ps1.executeQuery(); //transaction 2 PreparedStatement ps2 = "Update tableName set locked=true where id="key"; ps2.executeUpdate(); connection.setautocommit(true);// here we allow other transactions threads to see the new value connection.setautocommit(false); //transaction 3 PreparedStatement ps3 = "Update tableName set aField="Sthg" where id="key" And date="D" and topic="T"; ps3.executeUpdate(); // reset locked to false PreparedStatement ps4 = "Update tableName set locked=false where id="key"; ps4.executeUpdate(); //commit connection.setautocommit(true);

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• Haskell: monadic takeWhile?

  - by Mark Rushakoff

  I have some functions written in C that I call from Haskell. These functions return IO (CInt). Sometimes I want to run all of the functions regardless of what any of them return, and this is easy. For sake of example code, this is the general idea of what's happening currently: Prelude> let f x = print x >> return x Prelude> mapM_ f [0..5] 0 1 2 3 4 5 Prelude> I get my desired side effects, and I don't care about the results. But now I need to stop execution immediately after the first item that doesn't return my desired result. Let's say a return value of 4 or higher requires execution to stop - then what I want to do is this: Prelude> takeWhile (<4) $ mapM f [0..5] Which gives me this error: <interactive:1:22: Couldn't match expected type `[b]' against inferred type `IO a' In the first argument of `mapM', namely `f' In the second argument of `($)', namely `mapM f ([0 .. 5])' In the expression: takeWhile (< 4) $ mapM f ([0 .. 5]) And that makes sense to me - the result is still contained in the IO monad, and I can't just compare two values contained in the IO monad. I know this is precisely the purpose of monads -- chaining results together and discarding operations when a certain condition is met -- but is there an easy way to "wrap up" the IO monad in this case to stop executing the chain upon a condition of my choosing, without writing an instance of MonadPlus? Can I just "unlift" the values from f, for the purposes of the takeWhile? Is this a solution where functors fit? Functors haven't "clicked" with me yet, but I sort of have the impression that this might be a good situation to use them. Update: @sth has the closest answer to what I want - in fact, that's almost exactly what I was going for, but I'd still like to see whether there is a standard solution that isn't explicitly recursive -- this is Haskell, after all! Looking back on how I worded my question, now I can see that I wasn't clear enough about my desired behavior. The f function I used above for an example was merely an example. The real functions are written in C and used exclusively for their side effects. I can't use @Tom's suggestion of mapM_ f (takeWhile (&lt;4) [0..5]) because I have no idea whether any input will really result in success or failure until executed. I don't actually care about the returned list, either -- I just want to call the C functions until either the list is exhausted or the first C function returns a failure code. In C-style pseudocode, my behavior would be: do { result = function_with_side_effects(input_list[index++]); } while (result == success && index < max_index); So again, @sth's answer performs the exact behavior that I want, except that the results may (should?) be discarded. A dropWhileM_ function would be equivalent for my purposes. Why isn't there a function like that or takeWhileM_ in Control.Monad? I see that there was a similar discussion on a mailing list, but it appears that nothing has come of that.

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• Ajax post not posting email address ?

  - by jeitjet

  UPDATE: It will not work in Firefox, but will work on any other browser. I even tried loading Firefox in safe mode (disabling all plugins, etc.) and still no worky. :( I'm trying to do an AJAX post (on form submission) to a separate PHP file, which works fine without trying to send an email address through the post. I'm fairly new to AJAX and pretty familiar with PHP. Here's my form and ajax call <form class="form" method="POST" name="settingsNotificationsForm"> <div class="clearfix"> <label>Email <em>*</em><small>A valid email address</small></label><input type="email" required="required" name="email" id="email" /> </div> <div class="clearfix"> <label>Email Notification<small>...when a new subscriber joins</small></label><input type="checkbox" name="subscribe_notifications" id="subscribe_notifications"> Receive an email notification with phone number when someone new subscribes to 'BIZDEMO' </div> <div class="clearfix"> <label>Email Notification<small>...when a subscriber cancels</small></label><input type="checkbox" name="unsubscribe_notifications" id="unsubscribe_notifications"> Receive an email notification with phone number when someone new unsubscribes to 'BIZDEMO' </div> <div class="action clearfix top-margin"> <button class="button button-gray" type="submit" id="notifications_submit"><span class="accept"></span>Save</button> </div> </form> and AJAX call: <script type="text/javascript"> jQuery(document).ready(function () { $("#notifications_submit").click(function() { var keyword_value = '<?php echo $keyword; ?>'; var email_address = $("input#email").val(); var subscribe_notifications_value = $("input#subscribe_notifications").attr('checked'); var unsubscribe_notifications_value = $("input#unsubscribe_notifications").attr('checked'); var data_values = { keyword : keyword_value, email : email_address, subscribe_notifications : subscribe_notifications_value, unsubscribe_notifications : unsubscribe_notifications_value }; $.ajax({ type: "POST", url: "../includes/ajax/update_settings.php", data: data_values, success: alert('Settings updated successfully!'), }); }); }); and receiving page: <?php include_once ("../db/db_connect.php"); $keyword = FILTER_INPUT(INPUT_POST, 'keyword' ,FILTER_SANITIZE_STRING); $email = FILTER_INPUT(INPUT_POST, 'email' ,FILTER_SANITIZE_EMAIL); $subscribe_notifications = FILTER_INPUT(INPUT_POST, 'subscribe_notifications' ,FILTER_SANITIZE_STRING); $unsubscribe_notifications = FILTER_INPUT(INPUT_POST, 'unsubscribe_notifications' ,FILTER_SANITIZE_STRING); $table = 'keyword_options'; $data_values = array('email' => $email, 'sub_notify' => $subscribe_notifications, 'unsub_notify' => $unsubscribe_notifications); foreach ($data_values as $name=>$value) { // See if keyword is already in database table $filter = array('keyword' => $keyword); $result = $db->find($table, $filter); if (count($result) > 0 && $new != true) { $where = array('keyword' => $keyword, 'keyword_meta' => $name); $data = array('keyword_value' => $value); $db->update($table, $where, $data); } else { $data = array('keyword' => $keyword, 'keyword_meta' => $name, 'keyword_value' => $value); $db->create($table, $data); $new = true; // If this is a new record, always go to else statement } } unset($value); Here are some weird things that happen: When I only enter text into the email field, (i.e. - abc), it works fine, posts correctly, etc. When I enter a bogus email address with the "." before the "@", it works fine When I enter a validated email address (with the "." after the "@"), the post fails. Ideas?

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• Fragment method and socket.io

  - by Tolgay Toklar

  I have a method,this method updates an array list in fragment.I can call this method in main activity like this public void getFromUser(String message) { addMessageToFragment("ok"); } public void addMessageToFragment(String message) { Log.w("Step 1",message); frgObj.addMessageToList("asd"); } getFromUser is calling from fragment(when user presses the button) this is working as well.But I am using socket.io in my app,when I try to call this method from socket.io,app is not working. public void on(String event, IOAcknowledge ack, Object... args) { try{ addMessageToFragment("ok"); } catch (JSONException e) {} } When this callback function calls,app is giving this errors: 08-19 11:57:24.813: W/System.err(4962): io.socket.SocketIOException: Exception was thrown in on(String, JSONObject[]). 08-19 11:57:24.813: W/System.err(4962): Message was: 5:::{"name":"listele","args":[{"mesaj":"123","gonderen":"781722165-tolgay007-DKSMIcIYGahPuKXriM83","alici":"tolgay007","blck_id":"781722165-tolgay007","out_username":"Anony-781722","ars_status":1,"longinf":"3aqghef","a_status":1}]} 08-19 11:57:24.813: W/System.err(4962): at io.socket.IOConnection.transportMessage(IOConnection.java:702) 08-19 11:57:24.813: W/System.err(4962): at io.socket.WebsocketTransport.onMessage(WebsocketTransport.java:82) 08-19 11:57:24.813: W/System.err(4962): at org.java_websocket.client.WebSocketClient.onWebsocketMessage(WebSocketClient.java:361) 08-19 11:57:24.813: W/System.err(4962): at org.java_websocket.WebSocketImpl.deliverMessage(WebSocketImpl.java:565) 08-19 11:57:24.813: W/System.err(4962): at org.java_websocket.WebSocketImpl.decodeFrames(WebSocketImpl.java:331) 08-19 11:57:24.813: W/System.err(4962): at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:152) 08-19 11:57:24.813: W/System.err(4962): at org.java_websocket.client.WebSocketClient.interruptableRun(WebSocketClient.java:247) 08-19 11:57:24.823: W/System.err(4962): at org.java_websocket.client.WebSocketClient.run(WebSocketClient.java:193) 08-19 11:57:24.823: W/System.err(4962): at java.lang.Thread.run(Thread.java:841) 08-19 11:57:24.823: W/System.err(4962): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6094) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewRootImpl.focusableViewAvailable(ViewRootImpl.java:2800) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.ViewGroup.focusableViewAvailable(ViewGroup.java:650) 08-19 11:57:24.823: W/System.err(4962): at android.view.View.setFlags(View.java:8878) 08-19 11:57:24.823: W/System.err(4962): at android.view.View.setFocusableInTouchMode(View.java:6114) 08-19 11:57:24.823: W/System.err(4962): at android.widget.AdapterView.checkFocus(AdapterView.java:718) 08-19 11:57:24.823: W/System.err(4962): at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:813) 08-19 11:57:24.823: W/System.err(4962): at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:6280) 08-19 11:57:24.823: W/System.err(4962): at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37) 08-19 11:57:24.823: W/System.err(4962): at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50) 08-19 11:57:24.823: W/System.err(4962): at android.widget.ArrayAdapter.notifyDataSetChanged(ArrayAdapter.java:286) 08-19 11:57:24.823: W/System.err(4962): at com.impact.ribony.ConversationFragment.addMessageToList(ConversationFragment.java:91) 08-19 11:57:24.823: W/System.err(4962): at com.impact.ribony.MainActivity.addMessageToFragment(MainActivity.java:344) 08-19 11:57:24.823: W/System.err(4962): at com.impact.ribony.MainActivity$2.on(MainActivity.java:183) 08-19 11:57:24.823: W/System.err(4962): at io.socket.IOConnection.on(IOConnection.java:908) 08-19 11:57:24.883: W/System.err(4962): at io.socket.IOConnection.transportMessage(IOConnection.java:697) I didn't understand this error.What can be cause this error ?

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• nil object in view when building objects on two different associations

  - by Shako

  Hello all. I'm relatively new to Ruby on Rails so please don't mind my newbie level! I have following models: class Paintingdescription < ActiveRecord::Base belongs_to :paintings belongs_to :languages end class Paintingtitle < ActiveRecord::Base belongs_to :paintings belongs_to :languages end class Painting < ActiveRecord::Base has_many :paintingtitles, :dependent => :destroy has_many :paintingdescriptions, :dependent => :destroy has_many :languages, :through => :paintingdescriptions has_many :languages, :through => :paintingtitles end class Language < ActiveRecord::Base has_many :paintingtitles, :dependent => :nullify has_many :paintingdescriptions, :dependent => :nullify has_many :paintings, :through => :paintingtitles has_many :paintings, :through => :paintingdescriptions end In my painting new/edit view, I would like to show the painting details, together with its title and description in each of the languages, so I can store the translation of those field. In order to build the languagetitle and languagedescription records for my painting and each of the languages, I wrote following code in the new method of my Paintings_controller.rb: @temp_languages = @languages @languages.size.times{@painting.paintingtitles.build} @painting.paintingtitles.each do |paintingtitle| paintingtitle.language_id = @temp_languages[0].id @temp_languages.slice!(0) end @temp_languages = @languages @languages.size.times{@painting.paintingdescriptions.build} @painting.paintingdescriptions.each do |paintingdescription| paintingdescription.language_id = @temp_languages[0].id @temp_languages.slice!(0) end In form partial which I call in the new/edit view, I have <% form_for @painting, :html => { :multipart => true} do |f| %> ... <% languages.each do |language| %> <p> <%= label language, language.name %> <% paintingtitle = @painting.paintingtitles[counter] %> <% new_or_existing = paintingtitle.new_record? ? 'new' : 'new' %> <% prefix = "painting[#{new_or_existing}_title_attributes][]" %> <% fields_for prefix, paintingtitle do |paintingtitle_form| %> <%= paintingtitle_form.hidden_field :language_id%> <%= f.label :title %><br /> <%= paintingtitle_form.text_field :title%> <% end %> <% paintingdescription = @painting.paintingdescriptions[counter] %> <% new_or_existing = paintingdescription.new_record? ? 'new' : 'new' %> <% prefix = "painting[#{new_or_existing}_title_attributes][]" %> <% fields_for prefix, paintingdescription do |paintingdescription_form| %> <%= paintingdescription_form.hidden_field :language_id%> <%= f.label :description %><br /> <%= paintingdescription_form.text_field :description %> <% end %> </p> <% counter += 1 %> <% end %> ... <% end %> But, when running the code, ruby encounters a nil object when evaluating paintingdescription.new_record?: You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.new_record? However, if I change the order in which I a) build the paintingtitles and painting descriptions in the paintings_controller new method and b) show the paintingtitles and painting descriptions in the form partial then I get the nil on the paintingtitles.new_record? call. I always get the nil for the objects I build in second place. The ones I build first aren't nil in my view. Is it possible that I cannot build objects for 2 different associations at the same time? Or am I missing something else? Thanks in advance!

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