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• "Special case" records for foreign key constraints

  - by keithjgrant

  Let's say I have a mysql table, called foo with a foreign key option_id constrained to the option table. When I create a foo record, the user may or may not have selected an option, and 'no option' is a viable selection. What is the best way to differentiate between 'null' (i.e. the user hasn't made a selection yet) and 'no option' (i.e. the user selected 'no option')? Right now, my plan is to insert a special record into the option table. Let's say that winds up with an id of 227 (this table already has a number of records at this point, so '1' isn't available). I have no need to access this record at a database level, and it would act as nothing more than a placeholder that the foreign key in the foo table can reference. So do I just hard-code '227' in my codebase when I'm creating 'foo' records where the user has selected 'no option'? The hard-coded id seems sloppy, and leaves room for error as the code is maintained down the road, but I'm not really sure of another approach.

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• What is a reasonable OSGi development workflow?

  - by levand

  I'm using OSGi for my latest project at work, and it's pretty beautiful as far as modularity and functionality. But I'm not happy with the development workflow. Eventually, I plan to have 30-50 separate bundles, arranged in a dependency graph - supposedly, this is what OSGi is designed for. But I can't figure out a clean way to manage dependencies at compile time. Example: You have bundles A and B. B depends on packages defined in A. Each bundle is developed as a separate Java project. In order to compile B, A has to be on the javac classpath. Do you: Reference the file system location of project A in B's build script? Build A and throw the jar into B's lib directory? Rely on Eclipse's "referenced projects" feature and always use Eclipse's classpath to build (ugh) Use a common "lib" directory for all projects and dump the bundle jars there after compilation? Set up a bundle repository, parse the manifest from the build script and pull down the required bundles from the repository? No. 5 sounds the cleanest, but also like a lot of overhead.

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• How to select LI except first and second ?

  - by Wazdesign

  Here is the structure of the content, I want to select all LI except the first two (ie no-link) jQuery(document).ready(function(){ var nosubnav = jQuery('.first-level li:not(:has(ul))'); var nosubnavsize = jQuery('.first-level li:not(:has(ul))').size(); jQuery(nosubnav).css('border' , '1px solid red'); alert('List item which does not have submenu '+nosubnavsize); }); div class="navigation-container"> <ul class="first-level"> <li><a href="#">No Link</a></li> <li><a href="#">No Link</a></li> <li><a href="#">Link 1</a></li> <li><a href="#">Link 2</a> <ul> <li><a href="#">Link2.1</a></li> <li><a href="#">Link2.2</a> <ul> <li><a href="#">Link 2.2.1</a></li> </ul> </li> </ul> </li> <li><a href="#">Link </a></li> </ul> </div> related Question : http://stackoverflow.com/questions/2771801/how-to-count-li-which-does-not-have-ul

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• Java - How to declare table[i][j] elements as instance variables?

  - by JDelage

  All, I am trying to code a Connect4 game. For this, I have created a P4Game class and a P4Board class which represents the i X j dimensions of the Connect4 board. In P4Game, I have the following: public class P4Game{ //INSTANCE VARIABLES private int nbLines; private int nbColumns; private P4Board [][] position; //CONSTRUCTOR public P4Game(int nbLines, int nbColumns){ this.nbColumns = nbColumns; this.nbLines = nbLines; P4Board [][] position = new P4Board [nbLines][nbColumns]; //Creates the table to receive the instances of the P4Board object.*/ for (int i=0; i<nbLines; i++){ for (int j=0; j<nbColumns; j++){ this.position[i][j] = new P4Board(i,j); //Meant to create each object at (line=i, column=j) } } } This causes a NullPointerException in the nested loops where I mention this.position[i][j]. I reference those objects in other methods of this class so I need them to be instance variables. I suppose the exception is due to the fact that I have not listed the table element position[i][j] as an instance variable at the beginning of the class. my question to people here is (1) is my assumption correct, and if so (2) what would be the syntax to declare instance variables of this form? Thank you all for your help with what I realize is a very basic question. Hopefully it will also benefit other newbies. Cheers, JDelage

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• iPhone - Problem with in-app purchases

  - by Satyam svv

  I've created iPhone app with in-app purchase. Now, I'm in testing phase. I created provisioning profile com.satyam.testapp In iTunes connected I created the application and uploaded the images, screen shots, desscription etc. I also created two id's for in-app purchase. One is com.satyam.testapp.book1 and the other one is com.satyam.testapp.book5 I created test account also for verifying my in-app purchases. Using com.stayam.testapp i created developer test profile and using the same in my developed application. I logged out the itunes app store account in my iphone. Now i started running my application on my iphone. Its saying that no items are there to purchase. But its not even asking me for credentials where i've to enter test account username and password..... how to debug it? Here's my delegate: - (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response { NSArray *myProduct = [[NSArray alloc] initWithArray:response.products]; for(int i=0;i<[myProduct count];i++) { SKProduct *product = [myProduct objectAtIndex:i]; NSLog(@"Name: %@ - Price: %f",[product localizedTitle],[[product price] doubleValue]); NSLog(@"Product identifier: %@", [product productIdentifier]); } for(NSString *invalidProduct in response.invalidProductIdentifiers) NSLog(@"Problem in iTunes connect configuration for product: %@", invalidProduct); [request autorelease]; [myProduct release]; }

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• Serializing Configurations for a Dependency Injection / Inversion of Control

  - by Joshua Starner

  I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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• How to prepare data for display on a silverlight chart using WCF RIA Services + Entity Framework

  - by Banford

  I've used WCF RIA services with Entity Framework to build a simple application which can display and updates data about school courses. This was done by following the Microsoft tutorials. Now I would like to have a chart which shows a count for how many courses are on a key stage. Example: Key Stage 3 - 20 courses Key Stage 4 - 32 courses Key Stage 5 - 12 courses Displayed on any form of chart. I have no problem binding data to the chart in XAML. My problem is that I do not know how to correct way of getting the data into that format. The generated CRUD methods are basic. I have a few thoughts about possible ways, but don't know which is correct, they are: Create a View in SQL server and map this to a separate Entity in the Entity Data Model. Generating new CRUD methods for this automatically. Customise the read method in the existing DomainService using .Select() .Distinct() etc. Don't know this syntax very well labda expressions/LINQ??? what is it? Any good quickstarts on it? Create a new class to store only the data required and create a read method for it. Tried this but didn't know how to make it work without a matching entity in the entity model. Something I am not aware of. I'm very new to this and struggling with the concepts so if there are useful blogs or documentation I've missed feel free to point me towards them. But I'm unsure of the terminology to use in my searches at the moment.

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• iPhone: Calling dealloc on parentViewController causes an exception

  - by arielcamus

  Hi, I'm dealing with viewDidUnload and dealloc methods and I've founded a problem when calling [super dealloc]; in parent view controller. I have a lot of view controllers with custom code which I have putted outside on a parent view controller. So, when defining my view controllers I set a reference to the super class: @interface LoginViewController : AbstractViewController Then, at the dealloc method I call the AbstractViewController dealloc method: //(Login View Controller code) - (void)dealloc { [user release]; [passwd release]; [super dealloc]; } [super dealloc] execute the following code: //(Abstract View Controller code) - (void)dealloc { [dbUtils release]; [loadingView release]; [super dealloc]; } If I simulate a memory warning on iPhone Simulator, the following exception is thrown: 2010-03-03 11:27:45.805 MyApp[71563:40b] Received simulated memory warning. 2010-03-03 11:27:45.808 MyApp[71563:40b] *** -[LoginViewController isViewLoaded]: message sent to deallocated instance 0x13b51b0 kill quit However, if I comment the [super dealloc] line in AbstractViewController the exception is not thrown and my app still running. Thank you for your help once again!

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• How to populate Range variable from a Sub/Function call?

  - by Ken Ingram

  I am trying to get this sub to work but the operationalRange variable is not being assigned. Despite the fact that the function selectBodyRow(bodyName) works fine. Sub sortRows(bodyName As String, ByRef wksht As Worksheet) Dim operationalRange As Range Set operationalRange = selectBodyRow(bodyName) Debug.Print "Sorting Worksheet: " & wksht.Name If Not operationalRange Is Nothing Then operationalRange.Select Debug.Print "Sorting " & operationalRange.Count & "Rows." ActiveWorkbook.Worksheets(wksht.Name).Sort.SortFields.Clear ActiveWorkbook.Worksheets(wksht.Name).Sort.SortFields.Add Key:=operationalRange, _ SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal ActiveWorkbook.Worksheets(wksht.Name).Sort.SortFields.Add Key:=operationalRange, _ SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal With ActiveWorkbook.Worksheets(wksht.Name).Sort .SetRange operationalRange .Header = xlGuess .MatchCase = False .Orientation = xlTopToBottom .SortMethod = xlPinYin .Apply End With Else MsgBox "Body is not being Set" End If End Sub The Sub being called by the above Sub is: Function selectBodyRow(bodyName As String) As Range Dim rangeStart As String, rangeEnd As String Dim selectionStart As Range, selectionEnd As Range Dim result As Range, srchRng As Range, cngrs As Variant If bodyName = "WEST" Then rangeStart = "<-WEST START->" rangeEnd = "<-WEST END->" ElseIf bodyName = "EAST" Then rangeStart = "<-EAST START->" rangeEnd = "<-EAST END->" End If Set srchRng = Range("A:A") srchRng.Select Set selectionStart = srchRng.Find(What:=rangeStart, After:=ActiveCell, LookIn _ :=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:= _ xlNext, MatchCase:=False, SearchFormat:=False) Set selectionEnd = srchRng.Find(What:=rangeEnd, After:=ActiveCell, LookIn _ :=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:= _ xlNext, MatchCase:=False, SearchFormat:=False) Set result = Range(selectionStart.Offset(1, 0), selectionEnd.Offset(-1, 0)) result.EntireRow.Select End Function

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• iPhone: Does it ever make sense for an object to retain its delegate?

  - by randombits

  According to the rules of memory management in a non garbage collected world, one is not supposed to retain a the calling object in a delegate. Scenario goes like this: I have a class that inherits from UITableViewController and contains a search bar. I run expensive search operations in a secondary thread. This is all done with an NSOperationQueue and subclasses NSOperation instances. I pass the controller as a delegate that adheres to a callback protocol into the NSOperation. There are edge cases when the application crashes because once an item is selected from the UITableViewController, I dismiss it and thus its retain count goes to 0 and dealloc gets invoked on it. The delegate didn't get to send its message in time as the results are being passed at about the same time the dealloc happens. Should I design this differently? Should I call retain on my controller from the delegate to ensure it exists until the NSOperation itself is dealloc'd? Will this cause a memory leak? Right now if I put a retain on the controller, the crashes goes away. I don't want to leak memory though and need to understand if there are cases where retaining the delegate makes sense. Just to recap. UITableViewController creates an NSOperationQueue and NSOperation that gets embedded into the queue. The UITableViewController passes itself as a delegate to NSOperation. NSOperation calls a method on UITableViewController when it's ready. If I retain the UITableViewController, I guarantee it's there, but I'm not sure if I'm leaking memory. If I only use an assign property, edge cases occur where the UITableViewController gets dealloc'd and objc_msgSend() gets called on an object that doesn't exist in memory and a crash is imminent.

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• If statement question iphone?

  - by NextRev

  I am creating a game where where you complete shapes and the area gets filled in. However, if there is an enemy bird within your shape, it will not fill in. I want to make it so that if you do trap a bird within your shape, you will lose a life. How can I write an if statement that pretty much says if the below code doesn't take place, then you lose a life. If it helps losing a life is called doDie in my code. -(void)fillMutablePath{ CGPoint movePoint = CGPointFromString([pointsToFillArray objectAtIndex:0]); CGPathMoveToPoint(fillPath, NULL, movePoint.x, movePoint.y); for (int i=0; i<[pointsToFillArray count]; i++) { CGPoint tempPoint = CGPointFromString([pointsToFillArray objectAtIndex:i]); CGPathAddLineToPoint(fillPath, NULL, tempPoint.x, tempPoint.y); } CGContextAddPath(gameViewObj._myContext, fillPath); CGContextFillPath(gameViewObj._myContext); CGPathRelease(fillPath); [pointsToFillArray removeAllObjects]; } if(fillMutablePath doesn't take place when making a shape){ [self doDie]; } Like i said above, the reason fillMutablePath wouldn't take place is because a bird would be trapped within the shape. Any help would be much appreciated!!

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• Why are my connections not closed even if I explicitly dispose of the DataContext?

  - by Chris Simpson

  I encapsulate my linq to sql calls in a repository class which is instantiated in the constructor of my overloaded controller. The constructor of my repository class creates the data context so that for the life of the page load, only one data context is used. In my destructor of the repository class I explicitly call the dispose of the DataContext though I do not believe this is necessary. Using performance monitor, if I watch my User Connections count and repeatedly load a page, the number increases once per page load. Connections do not get closed or reused (for about 20 minutes). I tried putting Pooling=false in my config to see if this had any effect but it did not. In any case with pooling I wouldn't expect a new connection for every load, I would expect it to reuse connections. I've tried putting a break point in the destructor to make sure the dispose is being hit and sure enough it is. So what's happening? Some code to illustrate what I said above: The controller: public class MyController : Controller { protected MyRepository rep; public MyController () { rep = new MyRepository(); } } The repository: public class MyRepository { protected MyDataContext dc; public MyRepository() { dc = getDC(); } ~MyRepository() { if (dc != null) { //if (dc.Connection.State != System.Data.ConnectionState.Closed) //{ // dc.Connection.Close(); //} dc.Dispose(); } } // etc } Note: I add a number of hints and context information to the DC for auditing purposes. This is essentially why I want one connection per page load

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• Java: Ignoring escapes when parsing XML

  - by Personman

  I'm using a DocumentBuilder to parse XML files. However, the specification for the project requires that within text nodes, strings like " and < be returned literally, and not turned into the corresponding ASCII values. A previous similar question, http://stackoverflow.com/questions/1979785/read-escaped-quote-as-escaped-quote-from-xml, received one answer that seems to be specific to Apache, and another that appears to simply not not do what it says it does. I'd love to be proven wrong on either count, however :) For reference, here is some code: file = new File(fileName); DocBderFac = DocumentBuilderFactory.newInstance(); DocBder = DocBderFac.newDocumentBuilder(); doc = DocBder.parse(file); NodeList textElmntLst = doc.getElementsByTagName(text); Element textElmnt = (Element) textElmntLst.item(0); NodeList txts = textElmnt.getChildNodes(); String txt = ((Node) txts.item(0)).getNodeValue(); System.out.println(txt); I would like that println() to produce things like &quot;3&gt;2&quot; instead of "3>2" which is what currently happens. Thanks!

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• curl post picture multipart/form-data, php cURL need help!

  - by user331071

  I'm trying to upload a picture to a specific website using php cURL but I don't really understand what parameters do I need to send because the data looks a bit weird . Here is what i got with the http analyzer Type : multipart/form-data; boundary=---------------------------182983931283 -----------------------------182983931283 Content-Disposition: form-data; name="file"; filename="Blue hills.jpg" Content-Type: image/jpeg Here appears the souce of the image itself like "ÿØÿàÿØÿàÿØÿàÿØÿàÿØÿàÿØÿà" -----------------------------182983931283 Content-Disposition: form-data; name="action" images -----------------------------182983931283 Content-Disposition: form-data; name="anonymous_email" Y -----------------------------182983931283 Content-Disposition: form-data; name="site_id" 1 -----------------------------182983931283 and so on other parameters. The issue that I have is that I don't understand what is the boundary, where do I get it from (because it doesn't appear in the html document that generates the POST and how should I make the post . If you would give me a simple example to post the above parameters to http://example.com I will definitely get the trick . Currently I'm using the following function to make the post : function processPicturesPage($title, $price, $numbedrooms, $description) { //Set the login parameters and initiate the Login process $fields = array( "changedImages" = "", "site_id" = "1", "posting_id" = "", "current_live_date" = "", "images_loaded" = "", "image_actions" = "", "title" = $title, ); foreach($fields as $key=$value) { $fields_string .= $key.'='.$value.'&'; } rtrim($fields_string,'&'); $URL = "http://www.example.com/cgi-bin/add_posting.pl"; return $this-processCurlrequest($URL, count($fields), $fields_string); } and in the processCurlrequest I have the curl options (cookies etc) and url .

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• Referencing not-yet-defined variables - Java

  - by user2537337

  Because I'm tired of solving math problems, I decided to try something more engaging with my very rusty (and even without the rust, very basic) Java skills. I landed on a super-simple people simulator, and thus far have been having a grand time working through the various steps of getting it to function. Currently, it generates an array of people-class objects and runs a for loop to cycle through a set of actions that alter the relationships between them, which I have stored in a 2d integer array. When it ends, I go look at how much they all hate each other. Fun stuff. Trouble has arisen, however, because I would like the program to clearly print what action is happening when it happens. I thought the best way to do this would be to add a string, description, to my "action" class (which stores variables for the actor, reactor, and the amount the relationship changes). This works to a degree, in that I can print a generic message ("A fight has occurred!") with no problem. However, ideally I would like it to be a little more specific ("Person A has thrown a rock at Person B's head!"). This latter goal is proving more difficult: attempting to construct an action with a description string that references actor and reactor gets me a big old error, "Cannot reference field before it is defined." Which makes perfect sense. I believe I'm not quite in programmer mode, because the only other way I can think to do this is an unwieldy switch statement that negates the need for each action to have its own nicely-packaged description. And there must be a neater way. I am not looking for examples of code, only a push in the direction of the right concept to handle this.

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• JavaScript window object element properties

  - by Timothy

  A coworker showed me the following code and asked me why it worked. <span id="myspan">Do you like my hat?</span> <script type="text/javascript"> var spanElement = document.getElementById("myspan"); alert("Here I am! " + spanElement.innerHTML + "\n" + myspan.innerHTML); </script> I explained that a property is attached to the window object with the name of the element's id when the browser parses the document which then contains a reference to the appropriate dom node. It's sort of as if window.myspan = document.getElementById("myspan") is called behind the scenes as the page is being rendered. The ensuing discussion we had raised a few of questions: The window object and most of the DOM are not part of the official JavaScript/ECMA standards, but is the above behavior documented in any other official literature, perhaps browser-related? The above works in a browser (at least the main contenders) because there is a window object, but fails in something like rhino. Is writing code that relys on this considered bad practice because it makes too many assumptions about the execution environment? Are there any browsers in which the above would fail, or is this considered standard behavior across the board? Does anyone here know the answers to those questions and would be willing to enlighten me? I tried a quick internet search, but I admit I'm not sure how to even properly phrase the query. Pointers to references and documentation are welcome.

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• Removing "Using temporary; Using filesort" from this MySQL select+join+group by query

  - by claytontstanley

  I have the following query: select t.Chunk as LeftChunk, t.ChunkHash as LeftChunkHash, q.Chunk as RightChunk, q.ChunkHash as RightChunkHash, count(t.ChunkHash) as ChunkCount from chunksubset as t join chunksubset as q on t.ID = q.ID group by LeftChunkHash, RightChunkHash And the following explain table: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subsets ref PRIMARY,IDIndex,SubsetIndex SubsetIndex 767 const 522014 "Using where; Using temporary; Using filesort" 1 SIMPLE subsets eq_ref PRIMARY,IDIndex,SubsetIndex PRIMARY 771 sotero.subsets.Id,const 1 "Using where; Using index" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 "Using where" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 note the "using temporary; using filesort". When this query is run, I quickly run out of RAM (presumably b/c of the temp table), and then the HDD kicks in, and the query slows to a halt. I thought it might be an index issue, so I started adding a few that sort of made sense: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment chunks 0 PRIMARY 1 ChunkId A 17796190 NULL NULL BTREE chunks 1 ChunkHashIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 IDIndex 1 Id A 1483015 NULL NULL BTREE chunks 1 ChunkIndex 1 Chunk A 243783 NULL NULL BTREE chunks 1 ChunkTypeIndex 1 ChunkType A 2 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 2 ChunkId A 17796190 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 2 ChunkType A 261708 NULL NULL BTREE chunks 1 chunkHashByIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByIDIndex 2 Id A 17796190 NULL NULL BTREE But still using the temporary table. The db engine is MyISAM. How can I get rid of the using temporary; using filesort in this query? Just changing to InnoDB w/o explaining the underlying cause is not a particularly satisfying answer. Besides, if the solution is to just add the proper index, then that's much easier than migrating to another db engine.

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• Update Options on Existing jQuery Object

  - by Vince Kronlein

  I'm using Bootstrap and DataTables in my app and I have a default initializer for tables based on class. I can just add the class data-table to the table and it gets instantiated with the default values I want. I'd like to know how to change or update specific options based on a specific table. if ($.fn.dataTable) { $('.data-table').dataTable( { sDom: "R<'row'<'span6'l><'span6'f>r>t<'row'<'span6'i><'span6'p>>", sPaginationType: "bootstrap", oLanguage: { "sLengthMenu": "_MENU_ &nbsp; records per page" }, aoColumnDefs: [ { "bSortable": false, "aTargets": [ 0 ] } ] }); } All my data tables have a checkbox in the first column so the above removal of sorting works for all of them. But I'd like to be able to update the aoColumnDefs on a table by table basis so I can add other columns that I don't want sorted. So let's say I have a table: $('#member-list'), how do I access this object and update it's datatables options in jQuery? I can't find any reference or help anywhere. Thanks a lot! -V

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• C# Virtual method call in constructor - how to refactor?

  - by Cristi Diaconescu

  I have an abstract class for database-agnostic cursor actions. Derived from that, there are classes that implement the abstract methods for handling database-specific stuff. The problem is, the base class ctor needs to call an abstract method - when the ctor is called, it needs to initialize the database-specific cursor. I know why this shouldn't be done, I don't need that explanation! This is my first implementation, that obviously doesn't work - it's the textbook "wrong way" of doing it. The overridden method accesses a field from the derived class, which is not yet instantiated: public abstract class CursorReader { private readonly int m_rowCount; protected CursorReader() { m_rowCount = CreateCursor(sqlCmd); //virtual call ! } protected abstract int CreateCursor(string sqlCmd); } public class SqlCursorReader : CursorReader { private SqlConnection m_sqlConnection; public SqlCursorReader(string sqlCmd, SqlConnection sqlConnection) { m_sqlConnection = sqlConnection; //field initialized here } protected override int CreateCursor(string sqlCmd) { //uses not-yet-initialized member *m_sqlConnection* //so this throws a NullReferenceException var cursor = new CustomCursor(sqlCmd, m_sqlConnection); return cursor.Count(); } } I will follow up with an answer on my attempts to fix this...

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• Using capistrano to deploy from different git branches

  - by Toms Mikoss

  I am using capistrano to deploy a RoR application. The codebase is in a git repository, and branching is widely used in development. Capistrano uses deploy.rb file for it's settings, one of them being the branch to deploy from. My problem is this: let's say I create a new branch A from master. The deploy file will reference master branch. I edit that, so A can be deployed to test environment. I finish working on the feature, and merge branch A into master. Since the deploy.rb file from A is fresher, it gets merged in and now the deploy.rb in master branch references A. Time to edit again. That's a lot of seemingly unnecessary manual editing - the parameter should always match current branch name. On top of that, it is easy to forget to edit the settings each and every time. What would be the best way to automate this process? Edit: Turns out someone already had done exactly what I needed.

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• Python: Created nested dictionary from list of paths

  - by sberry2A

  I have a list of tuples the looks similar to this (simplified here, there are over 14,000 of these tuples with more complicated paths than Obj.part) [ (Obj1.part1, {<SPEC>}), (Obj1.partN, {<SPEC>}), (ObjK.partN, {<SPEC>}) ] Where Obj goes from 1 - 1000, part from 0 - 2000. These "keys" all have a dictionary of specs associated with them which act as a lookup reference for inspecting another binary file. The specs dict contains information such as the bit offset, bit size, and C type of the data pointed to by the path ObjK.partN. For example: Obj4.part500 might have this spec, {'size':32, 'offset':128, 'type':'int'} which would let me know that to access Obj4.part500 in the binary file I must unpack 32 bits from offset 128. So, now I want to take my list of strings and create a nested dictionary which in the simplified case will look like this data = { 'Obj1' : {'part1':{spec}, 'partN':{spec} }, 'ObjK' : {'part1':{spec}, 'partN':{spec} } } To do this I am currently doing two things, 1. I am using a dotdict class to be able to use dot notation for dictionary get / set. That class looks like this: class dotdict(dict): def __getattr__(self, attr): return self.get(attr, None) __setattr__ = dict.__setitem__ __delattr__ = dict.__delitem__ The method for creating the nested "dotdict"s looks like this: def addPath(self, spec, parts, base): if len(parts) > 1: item = base.setdefault(parts[0], dotdict()) self.addPath(spec, parts[1:], item) else: item = base.setdefault(parts[0], spec) return base Then I just do something like: for path, spec in paths: self.lookup = dotdict() self.addPath(spec, path.split("."), self.lookup) So, in the end self.lookup.Obj4.part500 points to the spec. Is there a better (more pythonic) way to do this?

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• C# Event Handlers Using an Enum

  - by Jimbo

  I have a StatusChanged event that is raised by my object when its status changes - however, the application needs to carry out additional actions based on what the new status is. e.g If the new status is Disconnected, then it must update the status bar text and send an email notification. So, I wanted to create an Enum with the possible statuses (Connected, Disconnected, ReceivingData, SendingData etc.) and have that sent with the EventArgs parameter of the event when it is raised (see below) Define the object: class ModemComm { public event CommanderEventHandler ModemCommEvent; public delegate void CommanderEventHandler(object source, ModemCommEventArgs e); public void Connect() { ModemCommEvent(this, new ModemCommEventArgs ModemCommEventArgs.eModemCommEvent.Connected)); } } Define the new EventArgs parameter: public class ModemCommEventArgs : EventArgs{ public enum eModemCommEvent { Idle, Connected, Disconnected, SendingData, ReceivingData } public eModemCommEvent eventType { get; set; } public string eventMessage { get; set; } public ModemCommEventArgs(eModemCommEvent eventType, string eventMessage) { this.eventMessage = eventMessage; this.eventType = eventType; } } I then create a handler for the event in the application: ModemComm comm = new ModemComm(); comm.ModemCommEvent += OnModemCommEvent; and private void OnModemCommEvent(object source, ModemCommEventArgs e) { } The problem is, I get a 'Object reference not set to an instance of an object' error when the object attempts to raise the event. Hoping someone can explain in n00b terms why and how to fix it :)

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• Objective C code to handle large amount of data processing in iPhone

  - by user167662

  I had the following code that takes in 14 mb or more of image data encoded in base4 string and converts them to jpeg before writing to a file in iphone. It crashes my program giving the following error : Program received signal: “0”. warning: check_safe_call: could not restore current frame I tweak my program and it can process a few more images before the error appear again. My coding is as follows: // parameters is an array where the fourth element contains a list of images in base64 >encoded string NSMutableArray *imageStrList = (NSMutableArray*) [parameters objectAtIndex:5]; while (imageStrList.count != 0) { NSString *imgString = [imageStrList objectAtIndex:0]; // Create a file name using my own Utility class NSString *fileName = [Utility generateFileNName]; NSData *restoredImg = [NSData decodeWebSafeBase64ForString:imgString]; UIImage *img = [UIImage imageWithData: restoredImg]; NSData *imgJPEG = UIImageJPEGRepresentation(img, 0.4f); [imgJPEG writeToFile:fileName atomically:YES]; [imageStrList removeObjectAtIndex:0]; } I tried playing around with UIImageJPEGRepresentation and found out that the lower the value, the more image it can processed but this should not be the way. I am wondering if there is anyway to free up memory of the imageStrList immediately after processing each image so that it can be used by the next one in the line.

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• GROUP BY ID range?

  - by d0ugal

  Given a data set like this; +-----+---------------------+--------+ | id | date | result | +-----+---------------------+--------+ | 121 | 2009-07-11 13:23:24 | -1 | | 122 | 2009-07-11 13:23:24 | -1 | | 123 | 2009-07-11 13:23:24 | -1 | | 124 | 2009-07-11 13:23:24 | -1 | | 125 | 2009-07-11 13:23:24 | -1 | | 126 | 2009-07-11 13:23:24 | -1 | | 127 | 2009-07-11 13:23:24 | -1 | | 128 | 2009-07-11 13:23:24 | -1 | | 129 | 2009-07-11 13:23:24 | -1 | | 130 | 2009-07-11 13:23:24 | -1 | | 131 | 2009-07-11 13:23:24 | -1 | | 132 | 2009-07-11 13:23:24 | -1 | | 133 | 2009-07-11 13:23:24 | -1 | | 134 | 2009-07-11 13:23:24 | -1 | | 135 | 2009-07-11 13:23:24 | -1 | | 136 | 2009-07-11 13:23:24 | -1 | | 137 | 2009-07-11 13:23:24 | -1 | | 138 | 2009-07-11 13:23:24 | 1 | | 139 | 2009-07-11 13:23:24 | 0 | | 140 | 2009-07-11 13:23:24 | -1 | +-----+---------------------+--------+ How would I go about grouping the results by day 5 records at a time. The above results is part of the live data, there is over 100,000 results rows in the table and its growing. Basically I want to measure the change over time, so want to take a SUM of the result every X records. In the real data I'll be doing it ever 100 or 1000 but for the data above perhaps every 5. If i could sort it by date I would do something like this; SELECT DATE_FORMAT(date, '%h%i') ym, COUNT(result) 'Total Games', SUM(result) as 'Score' FROM nn_log GROUP BY ym; I can't figure out a way of doing something similar with numbers. The order is sorted by the date but I hope to split the data up every x results. It's safe to assume there are no blank rows. Doing it above with the data you could do multiple selects like; SELECT SUM(result) FROM table LIMIT 0,5; SELECT SUM(result) FROM table LIMIT 5,5; SELECT SUM(result) FROM table LIMIT 10,5; Thats obviously not a very good way to scale up to a bigger problem. I could just write a loop but I'd like to reduce the number of queries.

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• jQuery: one-liner for removing all children but one

  - by user1352530

  HTML code is: <li> <a href="#" /> <ul> <li> <a href="#"/> </li> </ul> </li> I want to delete any node under $(this) = li that is not a link. If there are more than one link, just the first one is saved, and if there are links inside the ul tag, they are not included because they are descendants and no childrens. Something like this (I am cloning and outputting html): $(this).clone().remove('not(a:first)').html(); //Assuming remove looks for "a" as a first child Does not work, so I try with this: $(this).clone().children().remove('not(a:first)').parent().html(); Does not work so I try with this: $(this).clone().remove('not(>a:first)').html(); I need the original element as a reference after removal for chaining more operations EDIT: Ok! Second one works with a little syntax correction as some appointed (:not( instead of not() but I would like to know if there is any other solution similar to the third line so I don't have to do children().remove().parent(). Thank you!

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