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• PPR in tr:selectOneChoice does not work

  - by Nhut Le

  Hi, I have a simple testing page that test my PPR on a selectOneChoice component. when select a value from selectOnechoice 1, the selected value will display on a output label and also reset the selected value and the other selectOneChoice. However, it prints the selected values to the label correctly but it can't set the selected value for the other selectOneChoice. and Here are my page and my value change event method. <tr:form id="nhutForm"> <tr:selectOneChoice id="one" value="#{nhutTestBean.one}" autoSubmit="true" immediate="true" valueChangeListener="#{nhutTestBean.onMyValueChanged}"> <tr:selectItem label="0" value="0"/> <tr:selectItem label="1" value="1"/> <tr:selectItem label="2" value="2"/> <tr:selectItem label="3" value="3"/> </tr:selectOneChoice> <tr:selectOneChoice id="two" value="#{nhutTestBean.two}" partialTriggers="one"> <f:selectItems value="#{nhutTestBean.myList}"/> </tr:selectOneChoice> <tr:outputText id="nhutTextBox" value="hello: #{nhutTestBean.output}" partialTriggers="one"/></tr:form> and my valueChangeEvent method: public void onMyValueChanged(ValueChangeEvent event) { this.setOutput((String)event.getNewValue()); this.setTwo((String)event.getNewValue()); } One thing I realize is that it calls my setTwo twice, the first the set the correct values, but the second time set it to null so that nothing would be selected for the two drop down box. please help. thank you so much.

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• how do I insert an hidden token in my form to prevent double posts? (PHP)

  - by jpjp

  I want to prevent users from accidentally posting a comment twice. I use the PRG (post redirect get) method, so that I insert the data on another page then redirect the user back to the page which shows the comment. This allows users to refresh as many times as they want. However this doesn't work when the user goes back and clicks submit again or when they click submit 100 times really fast. I don't want 100 of the same comments. I looked at related questions on SO and found that a token is best. But I am having trouble using it. //makerandomtoken(20) returns a random 20 length char. <form method="post" ... > <input type="text" id="comments" name="comments" class="commentbox" /><br/> <input type="hidden" name="_token" value="<?php echo $token=makerandomtoken(20); ?>" /> <input type="submit" value="submit" name="submit" /> </form> if (isset($_POST['submit']) && !empty($comments)) { $comments= mysqli_real_escape_string($dbc,trim($_POST['comments'])); //how do I make the if-statment to check if the token has been already set once? if ( ____________){ //don't insert comment because already clicked submit } else{ //insert the comment into the database } } So I have the token as a hidden value, but how do I use that to prevent multiple clicking of submit.

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• Adding one subquery makes query a little slower, adding another makes it way slower

  - by Jason Swett

  This is fast: select ba.name, penamt.value penamt, #address_line4.value address_line4 from account a join customer c on a.customer_id = c.id join branch br on a.branch_id = br.id join bank ba on br.bank_id = ba.id join account_address aa on aa.account_id = a.id join address ad on aa.address_id = ad.id join state s on ad.state_id = s.id join import i on a.import_id = i.id join import_bundle ib on i.import_bundle_id = ib.id join (select * from unused where heading_label = 'PENAMT') penamt ON penamt.account_id = a.id #join (select * from unused where heading_label = 'Address Line 4') address_line4 ON address_line4.account_id = a.id where i.active=1 And this is fast: select ba.name, #penamt.value penamt, address_line4.value address_line4 from account a join customer c on a.customer_id = c.id join branch br on a.branch_id = br.id join bank ba on br.bank_id = ba.id join account_address aa on aa.account_id = a.id join address ad on aa.address_id = ad.id join state s on ad.state_id = s.id join import i on a.import_id = i.id join import_bundle ib on i.import_bundle_id = ib.id #join (select * from unused where heading_label = 'PENAMT') penamt ON penamt.account_id = a.id join (select * from unused where heading_label = 'Address Line 4') address_line4 ON address_line4.account_id = a.id where i.active=1 But this is slow: select ba.name, penamt.value penamt, address_line4.value address_line4 from account a join customer c on a.customer_id = c.id join branch br on a.branch_id = br.id join bank ba on br.bank_id = ba.id join account_address aa on aa.account_id = a.id join address ad on aa.address_id = ad.id join state s on ad.state_id = s.id join import i on a.import_id = i.id join import_bundle ib on i.import_bundle_id = ib.id join (select * from unused where heading_label = 'PENAMT') penamt ON penamt.account_id = a.id join (select * from unused where heading_label = 'Address Line 4') address_line4 ON address_line4.account_id = a.id where i.active=1 Why is it fast when I include just one of the two subqueries but slow when I include both? I would think it should be twice as slow when I include both, but it takes a really long time. On on MySQL.

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• How to interpolate in MatLab

  - by G Sam

  I have a 1x1 Matrix of points which specifies speed of a drive with respect to time. This speed changes throughout the operation; which means that the difference between two points is changing. To give you an example: M = [1; 2; 3; 5; 7; 9; 11; 15; 19]. (Only that this is a 892x1 matrix) I want to make this matrix twice as long (so changing the relative speed per timestep), while retaining the way the speeds change. Eg: M' = [1; 1.5; 2; 2.5; 3; 4; 5; 6; 7; 8; 9; 10; 11; 13; 15; 17; 19]. Is there an easy way to do this in MatLab? So far I have tried upsampling (which fills the time step with zeros); interp (which fills it with low-pass interpolation. Thanks!

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• Why are my events being called more than once?

  - by Arms

  In my Flash project I have a movieclip that has 2 keyframes. Both frames contain 1 movieclip each. frame 1 - Landing frame 2 - Game The flow of the application is simple: User arrives on landing page (frame 1) User clicks "start game" button User is brought to the game page (frame 2) When the game is over, the user can press a "play again" button which brings them back to step 1 Both Landing and Game movieclips are linked to separate classes that define event listeners. The problem is that when I end up back at step 1 after playing the game, the Game event listeners fire twice for their respective event. And if I go through the process a third time, the event listeners fire three times for every event. This keeps happening, so if I loop through the application flow 7 times, the event listeners fire seven times. I don't understand why this is happening because on frame 1, the Game movieclip (and I would assume its related class instance) does not exist - but I'm clearly missing something here. I've run into this problem in other projects too, and tried fixing it by first checking if the event listeners existed and only defining them if they didn't, but I ended up with unexpected results that didn't really solve the problem. I need to ensure that the event listeners only fire once. Any advice & insight would be greatly appreciated, thanks!

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• Counting computers for each lab

  - by Irvin

  Alright I have a problem with having to count PCs, and Macs from different labs. In each lab I need to display how many PC and Macs there is available. The data is coming from a SQL server, right am trying sub queries and the use of union, this the closest I can get to what I need. The query below shows me the number of PCs, and Macs in two different columns, but of course, the PCs will be in one row and the Macs on another right below it. Having the lab come up twice. EX: LabName -- PC / MAC Lab1 -- 5 / 0 Lab1 -- 0 / 2 Query SELECT Labs.LabName, COUNT(*),0 AS Mac FROM HardWare INNER JOIN Labs ON HardWare.LabID = Labs.LabID WHERE ComputerStatus = 'AVAILABLE' GROUP BY Labs.LabName UNION SELECT Labs.LabName, COUNT(*), (SELECT COUNT(Manufacturer)) AS Mac FROM HardWare INNER JOIN Labs ON HardWare.LabID = Labs.LabID WHERE ComputerStatus = 'AVAILABLE' AND Manufacturer = 'Apple' GROUP BY Labs.LabName ORDER BY Labs.LabName So is there any way to get them together in one row as in Lab1 -- 5 / 2 or is there a different way to write the query? anything will be a big help, am pretty much stuck here. Cheers

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• Is Form validation and Business validation too much?

  - by Robert Cabri

  I've got this question about form validation and business validation. I see a lot of frameworks that use some sort of form validation library. You submit some values and the library validates the values from the form. If not ok it will show some errors on you screen. If all goes to plan the values will be set into domain objects. Here the values will be or, better said, should validated (again). Most likely the same validation in the validation library. I know 2 PHP frameworks having this kind of construction Zend/Kohana. When I look at programming and some principles like Don't Repeat Yourself (DRY) and single responsibility principle (SRP) this isn't a good way. As you can see it validates twice. Why not create domain objects that do the actual validation. Example: Form with username and email form is submitted. Values of the username field and the email field will be populated in 2 different Domain objects: Username and Email class Username {} class Email {} These objects validate their data and if not valid throw an exception. Do you agree? What do you think about this aproach? Is there a better way to implement validations? I'm confused about a lot of frameworks/developers handling this stuff. Are they all wrong or am I missing a point? Edit: I know there should also be client side kind of validation. This is a different ballgame in my Opinion. If You have some comments on this and a way to deal with this kind of stuff, please provide.

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• Why do my CouchDB databases grow so fast?

  - by konrad

  I was wondering why my CouchDB database was growing to fast so I wrote a little test script. This script changes an attributed of a CouchDB document 1200 times and takes the size of the database after each change. After performing these 1200 writing steps the database is doing a compaction step and the db size is measured again. In the end the script plots the databases size against the revision numbers. The benchmarking is run twice: The first time the default number of document revision (=1000) is used (_revs_limit). The second time the number of document revisions is set to 1. The first run produces the following plot The second run produces this plot For me this is quite an unexpected behavior. In the first run I would have expected a linear growth as every change produces a new revision. When the 1000 revisions are reached the size value should be constant as the older revisions are discarded. After the compaction the size should fall significantly. In the second run the first revision should result in certain database size that is then keeps during the following writing steps as every new revision leads to the deletion of the previous one. I could understand if there is a little bit of overhead needed to manage the changes but this growth behavior seems weird to me. Can anybody explain this phenomenon or correct my assumptions that lead to the wrong expectations?

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• Strange behavior with complex Q object filter queries in Django

  - by HWM-Rocker

  Hi I am trying to write a tagging system for Django, but today I encountered a strange behavior in filter or the Q object (django.db.models.Q). I wrote a function, that converts a search string into a Q object. The next step would be to filter the TaggedObject with these query. But unfortunately I get a strange behavior. when I search (id=20) = Q: (AND: ('tags__tag__id', 20)) and it returns 2 Taged Objects with the ID 1127 and 132 when I search (id=4) = Q: (AND: ('tags__tag__id', 4)) and it returns also 2 Objects, but this time 1180 and 1127 until here is everything fine, but when i make a little bit more complex query like (id=4) or (id=20) = Q: (OR: ('tags__tag__id', 4), ('tags__tag__id', 20)) then it returns 4(!) Objects 1180, 1127, 1127, 132 But the object with the ID 1127 is returned twice, but thats not the behaviour I want. Do I have to live with it, and uniqify that list or can I do something different. The representation of the Q object looks fine for me. But the worst is now, when I search for (id=20) and (id=4) = Q: (AND: ('tags__tag__id', 20), ('tags__tag__id', 4)) then it returns no object at all. But why? The representation should be ok and the object with the id 1127 is tagged by both. What am I missing? Here are also the relevant parts of the classes, that are involved: class TaggedObject(models.Model): """ class that represent a tagged object """ tags = generic.GenericRelation('ObjectTagBridge', blank=True, null=True) class ObjectTagBridge(models.Model): """ Help to connect a generic object to a Tag. """ # pylint: disable-msg=W0232,R0903 content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') tag = models.ForeignKey('Tag') class Tag(models.Model): ... Thanks for your help

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• MySQL - optimising selection across two linked tables

  - by user293594

  I have two MySQL tables, states and trans: states (200,000 entries) looks like: id (INT) - also the primary key energy (DOUBLE) [other stuff] trans (14,000,000 entries) looks like: i (INT) - a foreign key referencing states.id j (INT) - a foreign key referencing states.id A (DOUBLE) I'd like to search for all entries in trans with trans.A 30. (say), and then return the energy entries from the (unique) states referenced by each matching entry. So I do it with two intermediate tables: CREATE TABLE ij SELECT i,j FROM trans WHERE A30.; CREATE TABLE temp SELECT DISTINCT i FROM ij UNION SELECT DISTINCT j FROM ij; SELECT energy from states,temp WHERE id=temp.i; This seems to work, but is there any way to do it without the intermediate tables? When I tried to create the temp table with a single command straight from trans: CREATE TABLE temp SELECT DISTINCT i FROM trans WHERE A30. UNION SELECT DISTINCT j FROM trans WHERE A30.; it took a longer (presumably because it had to search the large trans table twice. I'm new to MySQL and I can't seem to find an equivalent problem and answer out there on the interwebs. Many thanks, Christian

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• Prevent Rails link_to_remote multiple submits w Javascript

  - by Chris

  In a Rails project I need to keep a link_to_remote from getting double-clicked. It looks like :before and :after are my only choices - they get prepended/appended to the onclick Ajax call, respectively. But if I try something like: :before => "self.stopObserving()" t,he Ajax is never run. If I try it for :after the Ajax is run but the link never stops observing. The solutions I've seen rely on creating a variable and blocking the whole form, but there are multiple link_to_remote rows on this page and it is valid to click more than one of them at a time - just not the same one twice. One variable per row declared outside of link_to_remote seems very kludgey... Instead of using Prototype I originally tried plain Javascript first for this proof of concept - but it fails too: <a href="#" onclick="self.onclick = function(){alert('foo');};"click</a just puts up an alert when clicked - the lambda here does nothing? This next one is more like the desired goal and should only alert the first time. But instead it alerts every time: <a href="#" onclick="alert('bar'); self.onclick = function(){return false;};"click</a All ideas appreciated!

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• Why does one of these statements compile in Scala but not the other?

  - by Jeff

  (Note: I'm using Scala 2.7.7 here, not 2.8). I'm doing something pretty simple -- creating a map based on the values in a simple, 2-column CSV file -- and I've completed it easily enough, but I'm perplexed at why my first attempt didn't compile. Here's the code: // Returns Iterator[String] private def getLines = Source.fromFile(csvFilePath).getLines // This doesn't compile: def mapping: Map[String,String] = { Map(getLines map { line: String => val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() }.toList:_*) } // This DOES compile def mapping: Map[String,String] = { def strPair(line: String): (String,String) = { val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() } Map(getLines.map( strPair(_) ).toList:_*) } The compiler error is CsvReader.scala:16: error: value toList is not a member of (St ring) = (java.lang.String, java.lang.String) [scalac] possible cause: maybe a semicolon is missing before `value toList'? [scalac] }.toList:_*) [scalac] ^ [scalac] one error found So what gives? They seem like they should be equivalent to me, apart from the explicit function definition (vs. anonymous in the nonworking example) and () vs. {}. If I replace the curly braces with parentheses in the nonworking example, the error is "';' expected, but 'val' found." But if I remove the local variable definition and split the string twice AND use parens instead of curly braces, it compiles. Can someone explain this difference to me, preferably with a link to Scala docs explaining the difference between parens and curly braces when used to surround method arguments?

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• SoundChannel, removeEventHandler, AS3

  - by pixelGreaser

  Is there a better way to use the sound channel is AS3? This works, but I hate it when I tap the play button twice and it starts doubling. Please advise. var mySound:Sound = new Sound(); playButton.addEventListener (MouseEvent.CLICK, myPlayButtonHandler); var myChannel:SoundChannel = new SoundChannel(); function myPlayButtonHandler (e:MouseEvent):void { myChannel = mySound.play(); } stopButton.addEventListener(MouseEvent.CLICK, onClickStop); function onClickStop(e:MouseEvent):void{ myChannel.stop(); } /*-----------------------------------------------------------------*/ //global sound buttons, add instance of 'killswitch' and 'onswitch' to stage killswitch.addEventListener(MouseEvent.CLICK, clipKillSwitch); function clipKillSwitch(e:MouseEvent):void{ var transform1:SoundTransform=new SoundTransform(); transform1.volume=0; flash.media.SoundMixer.soundTransform=transform1; } onswitch.addEventListener(MouseEvent.CLICK, clipOnSwitch); function clipOnSwitch(e:MouseEvent):void{ var transform1_:SoundTransform=new SoundTransform(); transform1_.volume=1; flash.media.SoundMixer.soundTransform=transform1_; }

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• Singleton Pattern combine with a Decorator

  - by Mike

  Attached is a classic Decorator pattern. My question is how would you modify the below code so that you can wrap zero or one of each topping on to the Pizza Right now I can have a Pepporini - Sausage -- Pepporini -- Pizza class driving the total cost up to $10, charging twice for Pepporini. I don't think I want to use the Chain of Responsibility pattern as order does not matter and not all toppings are used? Thank you namespace PizzaDecorator { public interface IPizza { double CalculateCost(); } public class Pizza: IPizza { public Pizza() { } public double CalculateCost() { return 8.00; } } public abstract class Topping : IPizza { protected IPizza _pizzaItem; public Topping(IPizza pizzaItem) { this._pizzaItem = pizzaItem; } public abstract double CalculateCost(); } public class Pepporini : Topping { public Pepporini(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + 0.50; } } public class Sausage : Topping { public Sausage(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + 1.00; } } public class Onions : Topping { public Onions(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + .25; } } }

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• Help with Assembly/SSE Multiplication

  - by Brett

  I've been trying to figure out how to gain some improvement in my code at a very crucial couple lines: float x = a*b; float y = c*d; float z = e*f; float w = g*h; all a, b, c... are floats. I decided to look into using SSE, but can't seem to find any improvement, in fact it turns out to be twice as slow. My SSE code is: Vector4 abcd, efgh, result; abcd = [float a, float b, float c, float d]; efgh = [float e, float f, float g, float h]; _asm { movups xmm1, abcd movups xmm2, efgh mulps xmm1, xmm2 movups result, xmm1 } I also attempted using standard inline assembly, but it doesn't appear that I can pack the register with the four floating points like I can with SSE. Any comments, or help would be greatly appreciated, I mainly need to understand why my calculations using SSE are slower than the serial C++ code? I'm compiling in Visual Studio 2005, on a Windows XP, using a Pentium 4 with HT if that provides any additional information to assit. Thanks in advance!

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• Accelerometer gravity components

  - by Dvd

  Hi, I know this question is definitely solved somewhere many times already, please enlighten me if you know of their existence, thanks. Quick rundown: I want to compute from a 3 axis accelerometer the gravity component on each of these 3 axes. I have used 2 axes free body diagrams to work out the accelerometer's gravity component in the world X-Z, Y-Z and X-Y axes. But the solution seems slightly off, it's acceptable for extreme cases when only 1 accelerometer axis is exposed to gravity, but for a pitch and roll of both 45 degrees, the combined total magnitude is greater than gravity (obtained by Xa^2+Ya^2+Za^2=g^2; Xa, Ya and Za are accelerometer readings in its X, Y and Z axis). More detail: The device is a Nexus One, and have a magnetic field sensor for azimuth, pitch and roll in addition to the 3-axis accelerometer. In the world's axis (with Z in the same direction as gravity, and either X or Y points to the north pole, don't think this matters much?), I assumed my device has a pitch (P) on the Y-Z axis, and a roll (R) on the X-Z axis. With that I used simple trig to get: Sin(R)=Ax/Gxz Cos(R)=Az/Gxz Tan(R)=Ax/Az There is another set for pitch, P. Now I defined gravity to have 3 components in the world's axis, a Gxz that is measurable only in the X-Z axis, a Gyz for Y-Z, and a Gxy for X-Y axis. Gxz^2+Gyz^2+Gxy^2=2*G^2 the 2G is because gravity is effectively included twice in this definition. Oh and the X-Y axis produce something more exotic... I'll explain if required later. From these equations I obtained a formula for Az, and removed the tan operations because I don't know how to handle tan90 calculations (it's infinity?). So my question is, anyone know whether I did this right/wrong or able to point me to the right direction? Thanks! Dvd

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• Match subpatterns in any order

  - by Yaroslav

  I have long regexp with two complicated subpatters inside. How i can match that subpatterns in any order? Simplified example: /(apple)?\s?(banana)?\s?(orange)?\s?(kiwi)?/ and i want to match both of apple banana orange kiwi apple orange banana kiwi It is very simplified example. In my case banana and orange is long complicated subpatterns and i don't want to do something like /(apple)?\s?((banana)?\s?(orange)?|(orange)?\s?(banana)?)\s?(kiwi)?/ Is it possible to group subpatterns like chars in character class? UPD Real data as requested: 14:24 26,37 Mb 108.53 01:19:02 06.07 24.39 19:39 46:00 my strings much longer, but it is significant part. Here you can see two lines what i need to match. First has two values: length (14 min 24 sec) and size 26.37 Mb. Second one has three values but in different order: size 108.53 Mb, length 01 h 19 m 02 s and date June, 07 Third one has two size and length Fourth has only length There are couple more variations and i need to parse all values. I have a regexp that pretty close except i can't figure out how to match patterns in different order without writing it twice. (?<size>\d{1,3}\[.,]\d{1,2}\s+(?:Mb)?)?\s? (?<length>(?:(?:01:)?\d{1,2}:\d{2}))?\s* (?<date>\d{2}\.\d{2}))? NOTE: that is only part of big regexp that forks fine already.

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• MVC 3, View Model for user registration process. Password validation not working properly

  - by sec_goat

  I am trying to create a user registration page using MVC 3, so that I can better understand the process of how it works, what's going on behind the scenes etc. I am running into some issues when trying to use [Compare] to check to see that the user entered the same password twice. I tried adding the ComparePassword field to my user model first, and found that would not work the way I wanted as I did not have the field in the database, so the obvious answer was to create a View Model using the same information including the ComparePassword field. So I now have created a User model and a RegistrationViewModel, however it appears that the [Compare] on the password is not returning anything, for instance no matter what I put in the two boxes, when I click create it gives no error, which seems to me to mean it was successfully validated. I am not sure what I am doing or not doing to make this work properly. I have tried updating the jQuery.Validate to the newest version as there were some bugs reported in older version, this has not helped my efforts. Below is a wall of code, that is what I am working with. } public class RegistrationViewModel { [Required] [StringLength(15, MinimumLength = 3)] [Display(Name = "User Name")] [RegularExpression(@"(\S)+", ErrorMessage = " White Space is not allowed in User Names")] [ScaffoldColumn(false)] public String Username { get; set; } [Required] [StringLength(15, MinimumLength = 3)] [Display(Name = "First Name")] public String firstName { get; set; } [Required] [StringLength(15, MinimumLength = 3)] [Display(Name = "Last Name")] public String lastName { get; set; } [Required] [Display(Name = "Email")] public String email { get; set; } [Required] [Display(Name = "Password")] [DataType(DataType.Password)] public String password { get; set; } [Required] [DataType(DataType.Password)] [Display(Name = "Re-enter Password")] [Compare("Password", ErrorMessage = "Passwords do not match.")] public String comparePassword { get; set; } }

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• jQuery e.target bubbling best practice ?

  - by olouv

  In my heavy-ajax code, i always bind "click" the body tag & act depending on $(e.target) & using $.fn.hasClass(). However when i click on an anchor that has a </span> tag inside, my $(e.target) equals this node, and not the parent anchor as i would like it to. From now on, i have used this trick (var $t = $(e.target);) : /** bubbling **/ if($t.get(0).tagName !== "A" && $t.get(0).tagName !== "AREA") { $t = $t.parent("a"); if(empty($t)) return true; //else console.log("$t.bubble()", $t); } It feels wrong somehow... Do you have any better implementation ? $.fn.live() does not solve my issue as it still returns the span as the target. Moreover i'm looking for speed (running on atom-based touch devices) & live appeared to be way slower (twice) : http://jsperf.com/bind-vs-click/3 In fact, as @Guffa pointed, using $.fn.live() solves the span bubbling issue as i don't need the event.target anymore. I guess there is no other "right" answer here (using bind).

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• JBoss Clustered Service that sends emails from txt file

  - by michael lucas

  I need a little push in the right direction. Here's my problem: I have to create an ultra-reliable service that sends email messages to clients whose addresses are stored in txt file on FTP server. Single txt file may contain unlimited number of entries. Most often the file contains about 300,000 entries. Service exposes interface with just two simple methods: TaskHandle sendEmails(String ftpFilePath); ProcessStatus checkProcessStatus(TaskHandle taskHandle); Method sendEmails() returns TaskHandle by which we can ask for ProcessStatus. For such a service to be reliable clustering is necessary. Processing single txt file might take a long time. Restarting one node in a cluster should have no impact on sending emails. We use JBoss AS 4.2.0 which comes with a nice HASingletonController that ensure one instance of service is running at given time. But once a fail-over happens, the second service should continue work from where the first one stopped. How can I share state between nodes in a cluster in such a way that leaves no possibility of sending some emails twice?

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• The fastest way to iterate through a collection of objects

  - by Trev

  Hello all, First to give you some background: I have some research code which performs a Monte Carlo simulation, essential what happens is I iterate through a collection of objects, compute a number of vectors from their surface then for each vector I iterate through the collection of objects again to see if the vector hits another object (similar to ray tracing). The pseudo code would look something like this for each object { for a number of vectors { do some computations for each object { check if vector intersects } } } As the number of objects can be quite large and the amount of rays is even larger I thought it would be wise to optimise how I iterate through the collection of objects. I created some test code which tests arrays, lists and vectors and for my first test cases found that vectors iterators were around twice as fast as arrays however when I implemented a vector in my code in was somewhat slower than the array I was using before. So I went back to the test code and increased the complexity of the object function each loop was calling (a dummy function equivalent to 'check if vector intersects') and I found that when the complexity of the function increases the execution time gap between arrays and vectors reduces until eventually the array was quicker. Does anyone know why this occurs? It seems strange that execution time inside the loop should effect the outer loop run time.

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• SQL query for selecting the firsts in a series by cloumn

  - by SP

  I'm having some trouble coming up with a query for what I am trying to do. I've got a table we'll call 'Movements' with the following columns: RecID(Key), Element(f-key), Time(datetime), Room(int) The table is holding a history of Movements for the Elements. One record contains the element the record is for, the time of the recorded location, and the room it was in at that time. What I would like are all records that indicate that an Element entered a room. That would mean the first (by time) entry for any element in a series of movements for that element in the same room. The input is a room number and a time. IE, I would like all of the records indicating that any Element entered room X after time Y. The closest I came was this Select Element, min(Time) from Movements where Time > Y and Room = x group by Element This will only give me one room entry record per Element though (If the Element has entered the room X twice since time Y I'll only get the first one back) Any ideas? Let me know if I have not explained this clearly. I'm using MS SQLServer 2005.

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• linq: SQL performance on high loaded web applications

  - by Alex

  I started working with linq to SQL several weeks ago. I got really tired of working with SQL server directly through the SQL queries (sqldatareader, sqlcommand and all this good stuff).  After hearing about linq to SQL and mvc I quickly moved all my projects to these technologies. I expected linq to SQL work slower but it suprisongly turned out to be pretty fast, primarily because I always forgot to close my connections when using datareaders. Now I don't have to worry about it. But there's one problem that really bothers me. There's one page that's requested thousands of times a day. The system gets data in the beginning, works with it and updates it. Primarily the updates are ++ @ -- (increase and decrease values). I used to do it like this UPDATE table SET value=value+1 WHERE ID=@I'd It worked with no problems obviously. But with linq to SQL the data is taken in the beginning, moved to the class, changed and then saved. Stats.registeredusers++; Db.submitchanges(); Let's say there were 100 000 users. Linq will say "let it be 100 001" instead of "let it be increased by 1". But if there value of users has already been increased (that happens in my site all the time) then linq will be like oops, this value is already 100 001. Whatever I'll throw an exception" You can change this behavior so that it won't throw an exception but it still will not set the value to 100 002. Like I said, it happened with me all the time. The stas value was increased twice a second on average. I simply had to rewrite this chunk of code with classic ado net. So my question is how can you solve the problem with linq

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• How to solve this simple PHP forloop issue?

  - by Londonbroil Wellington

  Here is the content of my flat file database: Jacob | Little | 22 | Male | Web Developer * Adam | Johnson | 45 | Male | President * Here is my php code: <?php $fopen = fopen('db.txt', 'r'); if (!$fopen) { echo 'File not found'; } $fread = fread($fopen, filesize('db.txt')); $records = explode('|', $fread); ?> <table border="1" width="100%"> <tr> <thead> <th>First Name</th> <th>Last Name</th> <th>Age</th> <th>Sex</th> <th>Occupation</th> </thead> </tr> <?php $rows = explode('*', $fread); for($i = 0; $i < count($rows) - 1; $i++) { echo '<tr>'; echo '<td>'.$records[0].'</td>'; echo '<td>'.$records[1].'</td>'; echo '<td>'.$records[2].'</td>'; echo '<td>'.$records[3].'</td>'; echo '<td>'.$records[4].'</td>'; echo '</tr>'; } fclose($fopen); ?> </table> Problem is I am getting the output of the first record repeated twice instead of 2 records one for Jacob and one for Adam. How to fix this?

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• PHP: What is an efficient way to parse a text file containing very long lines?

  - by Shaun

  I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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