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  • Best way to carry & modify a variable through various instances and functions?

    - by bobsoap
    I'm looking for the "best practice" way to achieve a message / notification system. I'm using an OOP-based approach for the script and would like to do something along the lines of this: if(!$something) $messages->add('Something doesn\'t exist!'); The add() method in the messages class looks somewhat like this: class messages { public function add($new) { $messages = $THIS_IS_WHAT_IM_LOOKING_FOR; //array $messages[] = $new; $THIS_IS_WHAT_IM_LOOKING_FOR = $messages; } } In the end, there is a method in which reads out $messages and returns every message as nicely formatted HTML. So the questions is - what type of variable should I be using for $THIS_IS_WHAT_IM_LOOKING_FOR? I don't want to make this use the database. Querying the db every time just for some messages that occur at runtime and disappear after 5 seconds just seems like overkill. Using global constants for this is apparently worst practice, since constants are not meant to be variables that change over time. I don't even know if it would work. I don't want to always pass in and return the existing $messages array through the method every time I want to add a new message. I even tried using a session var for this, but that is obviously not suited for this purpose at all (it will always be 1 pageload too late). Any suggestions? Thanks!

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  • How to avoid geometric slowdown with large Linq transactions?

    - by Shaul
    I've written some really nice, funky libraries for use in LinqToSql. (Some day when I have time to think about it I might make it open source... :) ) Anyway, I'm not sure if this is related to my libraries or not, but I've discovered that when I have a large number of changed objects in one transaction, and then call DataContext.GetChangeSet(), things start getting reaalllly slooowwwww. When I break into the code, I find that my program is spinning its wheels doing an awful lot of Equals() comparisons between the objects in the change set. I can't guarantee this is true, but I suspect that if there are n objects in the change set, then the call to GetChangeSet() is causing every object to be compared to every other object for equivalence, i.e. at best (n^2-n)/2 calls to Equals()... Yes, of course I could commit each object separately, but that kinda defeats the purpose of transactions. And in the program I'm writing, I could have a batch job containing 100,000 separate items, that all need to be committed together. Around 5 billion comparisons there. So the question is: (1) is my assessment of the situation correct? Do you get this behavior in pure, textbook LinqToSql, or is this something my libraries are doing? And (2) is there a standard/reasonable workaround so that I can create my batch without making the program geometrically slower with every extra object in the change set?

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  • How to deal with a Java serialized object whose package changed?

    - by Alex
    I have a Java class that is stored in an HttpSession object that's serialized and transfered between servers in a cluster environment. For the purpose of this explanation, lets call this class "Person". While in the process of improving the code, this class was moved from "com.acme.Person" to "com.acme.entity.Person". Internally, the class remains exactly the same (same fields, same methods, same everything). The problem is that we have two sets of servers running the old code and the new code at the same time. The servers with the old code have serialized HttpSession object and when the new code unserializes it, it throws a ClassNotFoundException because it can't find the old reference to com.acme.Person. At this point, it's easy to deal with this because we can just recreate the object using the new package. The problem then becomes that the HttpSession in the new servers, will serialize the object with the new reference to com.acme.entity.Person, and when this is unserialized in the servers running the old code, another exception will be thrown. At this point, we can't deal with this exception anymore. What's the best strategy to follow for this kind of cases? Is there a way to tell the new servers to serialize the object with the reference to the old package and unserialize references to the old package to the new one? How would we transition to using the new package and forgetting about the old one once all servers run the new code?

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  • MySQL: Limit rows linked to each joined row

    - by SolidSnakeGTI
    Hello, Specifications: MySQL 4.1+ I've certain situation that requires certain result set from MySQL query, let's see the current query first & then ask my question: SELECT thread.dateline AS tdateline, post.dateline AS pdateline, MIN(post.dateline) FROM thread AS thread LEFT JOIN post AS post ON(thread.threadid = post.threadid) LEFT JOIN forum AS forum ON(thread.forumid = forum.forumid) WHERE post.postid != thread.firstpostid AND thread.open = 1 AND thread.visible = 1 AND thread.replycount >= 1 AND post.visible = 1 AND (forum.options & 1) AND (forum.options & 2) AND (forum.options & 4) AND forum.forumid IN(1,2,3) GROUP BY post.threadid ORDER BY tdateline DESC, pdateline ASC As you can see, mainly I need to select dateline of threads from 'thread' table, in addition to dateline of the second post of each thread, that's all under the conditions you see in the WHERE CLAUSE. Since each thread has many posts, and I need only one result per thread, I've used GROUP BY CLAUSE for that purpose. This query will return only one post's dateline with it's related unique thread. My questions are: How to limit returned threads per each forum!? Suppose I need only 5 threads -as a maximum- to be returned for each forum declared in the WHERE CLAUSE 'forum.forumid IN(1,2,3)', how can this be achieved. Is there any recommendations for optimizing this query (of course after solving the first point)? Notes: I prefer not to use sub-queries, but if it's the only solution available I'll accept it. Double queries not recommended. I'm sure there's a smart solution for this situation. Appreciated advice in advance :)

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  • Determing if an unordered vector<T> has all unique elements

    - by Hooked
    Profiling my cpu-bound code has suggested I that spend a long time checking to see if a container contains completely unique elements. Assuming that I have some large container of unsorted elements (with < and = defined), I have two ideas on how this might be done: The first using a set: template <class T> bool is_unique(vector<T> X) { set<T> Y(X.begin(), X.end()); return X.size() == Y.size(); } The second looping over the elements: template <class T> bool is_unique2(vector<T> X) { typename vector<T>::iterator i,j; for(i=X.begin();i!=X.end();++i) { for(j=i+1;j!=X.end();++j) { if(*i == *j) return 0; } } return 1; } I've tested them the best I can, and from what I can gather from reading the documentation about STL, the answer is (as usual), it depends. I think that in the first case, if all the elements are unique it is very quick, but if there is a large degeneracy the operation seems to take O(N^2) time. For the nested iterator approach the opposite seems to be true, it is lighting fast if X[0]==X[1] but takes (understandably) O(N^2) time if all the elements are unique. Is there a better way to do this, perhaps a STL algorithm built for this very purpose? If not, are there any suggestions eek out a bit more efficiency?

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  • Display data FROM Sheet1 on Sheet2 based on conditional value

    - by Shawn
    Imagine a worksheet with 30 pieces of information, such as: A1= Start Date A2 = End Date A3 = Resource Name A4 = Cost .... A30 = Whatever B1 = 1/1/2010 B2 = 2/15/2010 B3 = Joe Smith B4 = $10,000.00 ... B30 = Blah Blah Now imagine a third column, C. The purpose of the third column is to determine WHICH report that row of data needs to appear in. C1 = Report 1 C2 = Report 1 and Report 2 C3 = Report 4 and Report 7 C4 = Report 1 and Report 5 ... C30 = Report 2 Each report is on Sheets 2, 3, 4, 5 and so on (depending on how many I decide to create). As you can see form my example above, some data may need to appear in multiple reports. For example, the data in Row 3 (Resource Name: Joe Smith) needs to appear in Report 4 and Report 7. That is to say, it needs to DYNAMICALLY appear on two additional worksheets. If I change the values in column C, then the reports need to update automatically. How can I create the worksheets which will serve as the reports such that they only diaplay the rows which have been "flagged" to be displayed in that report? Thanks!

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  • Android Service setForeground While Display Sleeps

    - by c12
    I have a background Android Service that's purpose is to communicate with another device (non-phone) using a Bluetooth socket. Everything works fine except that the service gets stopped and restarted by the OS when the phone display is sleeping. This restart sometimes leaves a 15-20 minute gaps where there is no communication between the Service and the Bluetooth device and I need to be able to query the device every minute. Is startForeground the proper approach? Attempted to use: startForeground(int, Notification) //still see gaps when phone sleeps Service: public class ForegroundBluetoothService extends Service{ private boolean isStarted = false; @Override public void onDestroy() { super.onDestroy(); stop(); } /** * @see android.app.Service#onBind(android.content.Intent) */ @Override public IBinder onBind(Intent intent) { return null; } /** * @see android.app.Service#onStartCommand(android.content.Intent, int, int) */ @Override public int onStartCommand(Intent intent, int flags, int startId) { loadServiceInForeground(); return(START_STICKY); } private void loadServiceInForeground() { if (!isStarted) { isStarted=true; Notification notification = new Notification(R.drawable.icon, "Service is Running...", System.currentTimeMillis()); Intent notificationIntent = new Intent(this, MainScreen.class); PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0); notification.setLatestEventInfo(this, "Notification Title", "Service is Running...", pendingIntent); startForeground(12345, notification); try{ queryTheBluetoothDevice(); } catch(Exception ex){ ex.printStackTrace(); } } } private void stop() { if (isStarted) { isStarted=false; stopForeground(true); } } }

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  • Questions about openid and dotnetauthentication

    - by chobo2
    Hi I am looking into openid and dotnetauthentication library. However I still go some outstanding questions. the id that comes back is that unique for each user? Can I store this id in a database as the userId(currently this field is a primary key and unique identifier) I read that you can try to request information such as email address but you may not give it to you. What happens if you need this information? I think it kinda sucks if I have to popup another field right away and ask for their email address and whatever else fields I need. Sort of seems to defeat the purpose a bit as I always considered a benefit of openid is that you don't have to fill out registration forms. Is it better to only have some predefined choices(google,yahoo,openid,facebook). Then letting them type in their own ones(ie gray out the field to let them type in a url). I am thinking of this because it goes back to point number 2 if they type in a provider that does not give me the information that I need I am then stuck. How do you a log person out? Do you just kill the form authentication ticket?

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  • How come the Actionscript 3 ENTER_FRAME event is crazy nuts?

    - by nstory
    So, I've been toying around with Flash, browsing through the documentation, and all that, and noticed that the ENTER_FRAME event seems to defy my expectation of a deterministic universe. Take the following example: (new MovieClip()).addEventListener(Event.ENTER_FRAME, function(ev) {trace("Test");}); Notice this anonymous MovieClip is not added to the display hierarchy, and any reference to it is immediately lost. It will actually print "Test" once a frame until it is garbage collected. How insane is that? The behavior of this is actually determined by when the garbage collector feels like coming around in all its unpredictable insanity! Is there a better way to create intermittent failures? Seriously. My two theories are that either the DisplayObject class stores weak references to all its instances for the purpose of dispatching ENTER_FRAME events, or, and much wilder, the Flash player actually scans the heap each frame looking for ENTER_FRAME listeners to pull on. Can any hardened Actionscript developer clue me in on how this works? (And maybe a why - the - f**k they thought this was a good idea?)

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  • Stopping Filter Display in Dynamic Data Entity Web App

    - by bert
    I'm currently experimenting with the Dynamic Data Entity Web App Project type in VS2008 SP1 and after reading many tutorials which offer helpful advice for problems I so far have no need of a solution to I have fallen at the first hurdle. In the DB I have made my entity model from I decided to start small with a table called "Companies" just to see if I could tweak the display into a satisfactory shape for this small table. The Companies table has a column called "contactid" which leads to a record filled with various contact information in a "contacts" table. The default created Entity Data Model has guessed that One companies could have many contact records. So it tries to be helpful and add a "Contact" filter onto the page that allows you to see all the Companies that share a particular set of contact info indexed by the "Contact Name" field. Unfortunately the contact table is a multi-purpose one that also stores contact info for customers and there are about 1000 times more customers than there are companies. So the Dropdown makes the page load time increase exponentially and produces no benefit. So I'd like to just stop the filter from appearing. Only problem is I don't have a clue how to switch it off. Google is so far proving recalcitrant on the matter so I wondered if anyone in here knew how to get rid of a useless filter.

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  • where to store temporary data in MVC 2.0 project

    - by StuffHappens
    Hello! I'm starting to learn MVC 2.0 and I'm trying to create a site with a quiz: user is asked a question and given several options of answer. If he chooses the right answer he gets some points, if he doesn't, he looses them. I tried to do this the following way public class HomeController : Controller { private ITaskGenerator taskGenerator = new TaskGenerator(); private string correctAnswer; public ActionResult Index() { var task = taskGenerator .GenerateTask(); ViewData["Task"] = task.Task; ViewData["Options"] = task.Options; correctAnswer= task.CorrectAnswer; return View(); } public ActionResult Answer(string id) { if (id == correctAnswer) return View("Correct") return View("Incorrect"); } } But I have a problem: when user answers the cotroller class is recreated and I loose correct answer. So what is the best place to store correct answer? Should I create a static class for this purpose? Thanks for your help!

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  • Should try...catch go inside or outside a loop?

    - by mmyers
    I have a loop that looks something like this: for(int i = 0; i < max; i++) { String myString = ...; float myNum = Float.parseFloat(myString); myFloats[i] = myNum; } This is the main content of a method whose sole purpose is to return the array of floats. I want this method to return null if there is an error, so I put the loop inside a try...catch block, like this: try { for(int i = 0; i < max; i++) { String myString = ...; float myNum = Float.parseFloat(myString); myFloats[i] = myNum; } } catch (NumberFormatException ex) { return null; } But then I also thought of putting the try...catch block inside the loop, like this: for(int i = 0; i < max; i++) { String myString = ...; try { float myNum = Float.parseFloat(myString); } catch (NumberFormatException ex) { return null; } myFloats[i] = myNum; } So my question is: is there any reason, performance or otherwise, to prefer one over the other? EDIT: The consensus seems to be that it is cleaner to put the loop inside the try/catch, possibly inside its own method. However, there is still debate on which is faster. Can someone test this and come back with a unified answer? (EDIT: did it myself, but voted up Jeffrey and Ray's answers)

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  • linq to xml selection/update

    - by gleasonomicon
    If I have the following xml, how would I use linq to xml blank out the date fields in each video node? I wanted to do it for the purpose of a comparison in a unit test. <?xml version="1.0" encoding="utf-8" standalone="yes" ?> <main> <videos> <video> <id>00000000-0000-0000-0000-000000000000</id> <title>Video Title</title> <videourl>http://sample.com</videourl> <thumbnail>http://sample.com</thumbnail> <dateCreated>2011-01-12T18:54:56.7318386-05:00</dateCreated> <dateModified>2011-02-12T18:54:56.7318386-05:00</dateModified> <Numbers> <Number>28</Number> <Number>78</Number> </Numbers> </video> <video> <id>00000000-0000-0000-0000-000000000000</id> <title>Video Title</title> <videourl>http://sample.com</videourl> <thumbnail>http://sample.com</thumbnail> <dateCreated>2011-01-12T18:54:56.7318386-05:00</dateCreated> <dateModified>2011-02-12T18:54:56.7318386-05:00</dateModified> <Numbers> <Number>28</Number> <Number>78</Number> </Numbers> </video> </videos>

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  • Can a conforming C# compiler optimize away a local (but unused) variable if it is the only strong re

    - by stakx
    The title says it all, but let me explain: void Case_1() { var weakRef = new WeakReference(new object()); GC.Collect(); // <-- doesn't have to be an explicit call; just assume that // garbage collection would occur at this point. if (weakRef.IsAlive) ... } In this code example, I obviously have to plan for the possibility that the new'ed object is reclaimed by the garbage collector; therefore the if statement. (Note that I'm using weakRef for the sole purpose of checking if the new'ed object is still around.) void Case_2() { var unusedLocalVar = new object(); var weakRef = new WeakReference(unusedLocalVar); GC.Collect(); // <-- doesn't have to be an explicit call; just assume that // garbage collection would occur at this point. Debug.Assert(weakReferenceToUseless.IsAlive); } The main change in this code example from the previous one is that the new'ed object is strongly referenced by a local variable (unusedLocalVar). However, this variable is never used again after the weak reference (weakRef) has been created. Question: Is a conforming C# compiler allowed to optimize the first two lines of Case_2 into those of Case_1 if it sees that unusedLocalVar is only used in one place, namely as an argument to the WeakReference constructor? i.e. is there any possibility that the assertion in Case_2 could ever fail?

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  • Best way to build an application based on R?

    - by Prasad Chalasani
    I'm looking for suggestions on how to go about building an application that uses R for analytics, table generation, and plotting. What I have in mind is an application that: displays various data tables in different tabs, somewhat like in Excel, and the columns should be sortable by clicking. takes user input parameters in some dialog windows. displays plots dynamically (i.e. user-input-dependent) either in a tab or in a new pop-up window/frame Note that I am not talking about a general-purpose fron-end/GUI for exploring data with R (like say Rattle), but a specific application. Some questions I'd like to see addressed are: Is an entirely R-based approach even possible ( on Windows ) ? The following passage from the Rattle article in R-Journal intrigues me: It is interesting to note that the first implementation of Rattle actually used Python for implementing the callbacks and R for the statistics, using rpy. The release of RGtk2 allowed the interface el- ements of Rattle to be written directly in R so that Rattle is a fully R-based application If it's better to use another language for the GUI part, which language is best suited for this? I'm looking for a language where it's relatively "painless" to build the GUI, and that also integrates very well with R. From this StackOverflow question How should I do rapid GUI development for R and Octave methods (possibly with Python)? I see that Python + PyQt4 + QtDesigner + RPy2 seems to be the best combo. Is that the consensus ? Anyone have pointers to specific (open source) applications of the type I describe, as examples that I can learn from?

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  • Datastructure choices for highspeed and memory efficient detection of duplicate of strings

    - by Jonathan Holland
    I have a interesting problem that could be solved in a number of ways: I have a function that takes in a string. If this function has never seen this string before, it needs to perform some processing. If the function has seen the string before, it needs to skip processing. After a specified amount of time, the function should accept duplicate strings. This function may be called thousands of time per second, and the string data may be very large. This is a highly abstracted explanation of the real application, just trying to get down to the core concept for the purpose of the question. The function will need to store state in order to detect duplicates. It also will need to store an associated timestamp in order to expire duplicates. It does NOT need to store the strings, a unique hash of the string would be fine, providing there is no false positives due to collisions (Use a perfect hash?), and the hash function was performant enough. The naive implementation would be simply (in C#): Dictionary<String,DateTime> though in the interest of lowering memory footprint and potentially increasing performance I'm evaluating a custom data structures to handle this instead of a basic hashtable. So, given these constraints, what would you use? EDIT, some additional information that might change proposed implementations: 99% of the strings will not be duplicates. Almost all of the duplicates will arrive back to back, or nearly sequentially. In the real world, the function will be called from multiple worker threads, so state management will need to be synchronized.

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  • How to open popup behind main window (HTML,jQuery)

    - by sara.ma
    I'm new. i have a popup code that when user click anywhere in the HTML page, a popup window shows up: (function () { document.onclick = function () { var sUrl = "http://URL.com"; if (typeof daily_capping == "undefined") var daily_capping = 10; if (typeof capping_minutes == "undefined") var capping_minutes = 60; if (document.cookie.indexOf("_popwin=") === -1) { var ads2day = document.cookie.split("_popwinDaily=")[1]; ads2day = typeof ads2day == "undefined" ? 0 : parseInt(ads2day.split(";")[0]); if (ads2day < daily_capping) { var isMSIE = navigator.userAgent.indexOf("MSIE") != -1 ? !0 : !1, _parent = self, sOptions, popunder; if (top != self) try { top.document.location.toString() && (_parent = top) } catch (err) {} sOptions = "toolbar=no,scrollbars=yes,location=yes,statusbar=yes,menubar=no,resizable=1,width=" + screen.width.toString() + ",height=" + (screen.height - 20).toString() + ",screenX=0,screenY=0,left=0,top=0", popunder = _parent.window.open(sUrl, "rhpop", sOptions); if (popunder) { popunder.blur(); if (isMSIE) { window.focus(); try { opener.window.focus() } catch (err) {} } else popunder.init = function (e) { with(e)(function () { if (typeof window.mozPaintCount != "undefined" || typeof navigator.webkitGetUserMedia == "function") { var e = window.open("about:blank"); e.close() } try { opener.window.focus() } catch (t) {} })() }, popunder.params = { url: sUrl }, popunder.init(popunder) } var now = new Date, popDaily = (new Date(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate(), 23, 59, 59)).toGMTString(); document.cookie = "_popwinDaily=" + (ads2day + 1) + ";expires=" + popDaily + ";path=/"; var popInterval = new Date; popInterval.setTime(popInterval.getTime() + capping_minutes * 60 * 1e3), document.cookie = "_popwin=1;expires=" + popInterval.toGMTString() + ";path=/" } } } })(); but popup is on top. is it possible to make it open behind main page?? is there any lighter popup code for this purpose? thanks guys

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  • How to rewrite data-driven test suites of JUnit 3 in Junit 4?

    - by rics
    I am using data-driven test suites running JUnit 3 based on Rainsberger's JUnit Recipes. The purpose of these tests is to check whether a certain function is properly implemented related to a set of input-output pairs. Here is the definition of the test suite: public static Test suite() throws Exception { TestSuite suite = new TestSuite(); Calendar calendar = GregorianCalendar.getInstance(); calendar.set(2009, 8, 05, 13, 23); // 2009. 09. 05. 13:23 java.sql.Date date = new java.sql.Date(calendar.getTime().getTime()); suite.addTest(new DateFormatTestToString(date, JtDateFormat.FormatType.YYYY_MON_DD, "2009-SEP-05")); suite.addTest(new DateFormatTestToString(date, JtDateFormat.FormatType.DD_MON_YYYY, "05/SEP/2009")); return suite; } and the definition of the testing class: public class DateFormatTestToString extends TestCase { private java.sql.Date date; private JtDateFormat.FormatType dateFormat; private String expectedStringFormat; public DateFormatTestToString(java.sql.Date date, JtDateFormat.FormatType dateFormat, String expectedStringFormat) { super("testGetString"); this.date = date; this.dateFormat = dateFormat; this.expectedStringFormat = expectedStringFormat; } public void testGetString() { String result = JtDateFormat.getString(date, dateFormat); assertTrue( expectedStringFormat.equalsIgnoreCase(result)); } } How is it possible to test several input-output parameters of a method using JUnit 4? This question and the answers explained to me the distinction between JUnit 3 and 4 in this regard. This question and the answers describe the way to create test suite for a set of class but not for a method with a set of different parameters.

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  • jquery problem in IE working fine in FF

    - by Bharanikumar
    function populate_customer_details(){ $.ajax({ type : 'POST', url : 'populate_customer_details.php', data: { email : $('#txt_email_id').val() }, success : function(data){ if(data=="NOROWSFOUND"){ alert("Sorry, Email ID not exist in our database"); document.getElementById("txt_email_id").focus(); }else{ var val = explode_all_into_arr(data,"|=|"); document.getElementById("FirstName").value = val[0]; document.getElementById("LastName").value = val[1]; document.getElementById("mobilecountrycode").value = parseInt(val[2]); document.getElementById("MobileNo").value = val[3]; document.getElementById("homecountrycode").value = parseInt(val[4]); document.getElementById("HomeNo").value = val[5]; document.getElementById("PaxEmail").value = val[6]; document.getElementById("PaxEmailConf").value = val[6]; } }, }); } This is my snippet purpose is getting the customer details and populate into textfield and combo box , That is Firstname will append into Firstname text field , Secondname will append into Secondname text field , Same like mobilecountrycode (but this is dropdown combo), Some time combo selectedindex work fine, but some time not selecting the value , I am not sure what s problem in that... Nothing works in IE , Also showing object expected error in IE , i have ajax_common.js : in this i added above script , in the page top first i included the jquery.js , Then i include ajax_common.js file, But no idea why this problem. Regards (NOTE i included the jquery.js ) ,

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  • Windows Phone 7 applications - Orientation Change

    - by Peter Perhác
    Hello there fellow developers! I am working on a Windows Phone 7 app and I can't figure out what I believe is a simple problem for the more seasoned ones. Say I have a layout consisting of two elements: a ListBox (filled with an abundance of items) and a TextBlock (providing the user with some basic instructions). I want these to be one above the other when the device is in Portrait orientation and I want these to be next to each other when the device orientation changes to Landscape. For the Portrait orientation I am using a Grid layout manager, as it lets me define the rows' heights like so... row 0 Height="2*", row 1 Height="*" Listbox sits in row 0, TextBlock in row 1. Now, what would be really neat is to simple change the RowDefinitions into ColumnDefinitions and reassign the listbox/textblock to the grid's columns instead of rows for when the device switches into Landscape. But that's just my idea. I don't know how to get this done elegantly. Maybe there's a better approach to this? Or maybe this is the correct approach and there is some method built for exactly this purpose? Thank you for your suggestions!

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  • 2-column table with two foreign keys. Performance/design question.

    - by Emanuel
    Hello everyone! I recently ran into a quite complex problem and after looking around a lot I couldn't find a solution to it. I've found answers to my questions many times before on stackoverflow.com, so I decided to post here. So I'm making a user/group managment system for a web-based project, and I'm storing all related data into a postgreSQL database. This system relies on three tables: USERS GROUPS GROUP_USERS The two first tables simply define all the users and all the groups on the site, and the last table, GROUP_USERS, stores the groups every user is part of. It only has two columns: USER_ID GROUP_ID Since every user can be a member of several groups, I decided to make a separate table for this purpose, rather than storing a comma separated column in the USERS-table. Now, both columns are foreign keys, and I want to make them both primary keys as well, this since each combination of USER_ID and GROUP_ID has to be unique, and if I give them the constraint UNIQUE pgAdmin tells me that each table should have at least one Primary key. But now I am stuck with what seems to be a lot of indexes and relations to a very small table only containing numbers. In the end, I want this table to be as fast as possible, even if containing tens of thousands of rows. Size on disk shouldn't be a problem since its just all numbers anyway, but it feels quite stupid to have a full-sized index refering to a smaller table. Should I stick with my current solution, store comma-separated values in a column in the USERS-table or is there any other solution I should be aware of. PS. I don't want to use an array-column, even if they are supported by postgreSQL. I want to be as generic as possible so I can switch database later on, if necessary. EDIT: I other words, will using a compound primary key and two foreign keys in one table with only two columns have a negative impact on performance rather than the opposite due to the size of the generated index? Thank you!

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  • Automatically Organize Tags in Tax/Folksonomy

    - by Rob Wilkerson
    I'm working on a process that will perform natural language processing (NLP) on one--and potentially several--of our content rich sites. What I'd like to do once the NLP is complete is to automatically organize the output (generally a set of terms that you might think of as tags given the prevalence of that metaphor) into some kind of standard or generally accepted organizational structure. In a perfect world, I'd really like this to be crowd sourced under the folksonomy concept (as opposed to a taxonomy) since the ultimate goal is to target/appeal to real people rather than "domain experts", but I'm open to ideas and best practices. For the obvious purpose of scalability, I'd like to automate the population of this tax/folksonomy so that "some guy" in the team/organization isn't responsible for looking at a bunch of words (with or without context) and arbitrarily fleshing out the contextual components of the tree. I have a few ideas for doing this that require some research to establish viability, but I have exactly zero practical experience with this sort of thing so the ideas really just boil down to stuff I made up that might perform some role in accomplishing the task. Imagining that others have vastly more experience with this sort of thing, I'm hoping that I can stand on your shoulders. Thanks for your thoughts and insights.

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  • mysql query not running correctly from inside the application

    - by Mala
    I am completely stumped. Here is my php (CodeIgniter) code: function mod() { $uid = $this->session->userdata('uid'); $pid = $this->input->post('pid'); if ($this->_verify($uid,$pid)) { $name = $this->input->post('name'); $price = $this->input->post('price'); $curr = $this->input->post('curr'); $url = $this->input->post('url'); $query = $this->db->query("UPDATE items SET name=".$this->db->escape($name).", price=".$this->db->escape($price).", currency=".$this->db->escape($curr),", url=".$this->db->escape($url)." WHERE pid=".$this->db->escape($pid)." LIMIT 1"); } header('location: '.$this->session->userdata('current')); } The purpose of this code is to modify the properties (name, price, currency, url) of a row in the 'items' table (priary key is pid). However, for some reason, allowing this function to run once modifies the name, price, currency and url of ALL entries in the table, regardless of their pid and of the LIMIT 1 thing I tacked on the end of the query. It's as if the last line of the query is being completely ignored. As if this wasn't strance enough, I replaced "$query = $this->db->query(" with an "echo" to see the SQL query being run, and it outputs a query much like I would expect: UPDATE items SET name='newname', price='newprice', currency='newcurrency', url='newurl' WHERE pid='10' LIMIT 1 Copy-pasting this into a MySQL window acts exactly as I want: it modifies the row with the selected pid. What is going on here???

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  • A beginner question on passthru() function in PHP

    - by Robert
    Hi all, I've used the following code to do an XSLT translation in PHP and save the result SVG file into a sub folder: $command = $java . $saxon . $target2 . ' ' . $xsl2.' '.$param; ob_start(); passthru($command, $result); $content_grabbed=ob_get_contents(); ob_end_clean(); $info = pathinfo($_FILES['file']['name']); $file_name= basename($_FILES['file']['name'],'.'.$info['extension']); $myFile = "images/convert/".$file_name."_".$_POST["mydropdown"].".svg"; $fh = fopen($myFile, 'w') or die("can't open file"); fwrite($fh, $content_grabbed); fclose($fh); It does a very simple SVG to SVG transformation, and created the resulting SVG file. the $command is just a simple java -jar saxon.jar input.xml stylesheet java command. The current situation is ,the file gets created perfectly, however, the error gets shown in browser, probably because I inserted the "ob_start" before passthru() command. I am thinking of making use of an argument that comes with the saxon.jar, that is "-o output_file_name". Because the final purpose is not to display the resulting SVG to the browser, but instead creating an SVG file ,and provide the link to the user for downloading. Are there any better ways to handle this problem, I am still thinking about how to get rid of the result that gets shown in the browser that is sent by the "passthru()". Thanks in advance for suggestions!

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  • How to get last Friday of month(s) using .NET

    - by Newbie
    I have a function that returns me only the fridays from a range of dates public static List<DateTime> GetDates(DateTime startDate, int weeks) { int days = weeks * 7; //Get the whole date range List<DateTime> dtFulldateRange = Enumerable.Range(-days, days).Select(i => startDate.AddDays(i)).ToList(); //Get only the fridays from the date range List<DateTime> dtOnlyFridays = (from dtFridays in dtFulldateRange where dtFridays.DayOfWeek == DayOfWeek.Friday select dtFridays).ToList(); return dtOnlyFridays; } Purpose of the function: "List of dates from the Week number specified till the StartDate i.e. If startdate is 23rd April, 2010 and the week number is 1,then the program should return the dates from 16th April, 2010 till the startddate". I am calling the function as: DateTime StartDate1 = DateTime.ParseExact("20100430", "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture); List<DateTime> dtList = Utility.GetDates(StartDate1, 4).ToList(); Now the requirement has changed a bit. I need to find out only the last Fridays of every month. The input to the function will remain same.

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