simple talk editorial team - Page 559

Drupal module for complex hours of operation / office hours

- by Eronarn

Background: I am building a website in Drupal that links together a wide variety of social service providers for the purposes of discovery, collaboration, and all that good stuff. The goal is to make a website that is simple to browse for consumers of these services and simple to update for providers of these services. The beta has been very well received, but I want to switch to a different information schema before the site goes live. Specific question: I am looking for a module (or other solution) that... Stores this data in Drupal (i.e., no GCal) Supports a wide variety of repeats Is intuitive for people editing the node (no Cron-style interfaces, please!) I have looked into several modules on drupal.org and none seem to meet all of these criteria. I've also searched here, and while this question is similar: http://stackoverflow.com/questions/2794149/drupal-create-a-node-with-employee-working-hours my needs are too complex for the offered solution. Some of these providers have "hours" such as "the third Wednesday of every month", or "open during Winter months", or separate hotline & office hours. Likewise, the Date Repeat module doesn't cut it as stands currently. I'm comfortable hacking what I need into an existing module - I just don't want to duplicate effort! If you have a suggestion on what module might be a good starting point, I'd appreciate that input, too. Thanks. <3

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HTML5 on iPhone Safari - data stored by localStorage does not always persist. Why?

- by Aerodyne

Hi, I write a simple iPhone web app using HTML5's localStorage. Tests on a 2G device show that data stored using localStorage does not persist after the Safari process is killed although the opened Safari windows are remembered. The data is also lost in a case where I am on a different site on a different Safari window, then I change the window to where the web app in subject is shown. When Safari loads the page it automatically refreshes the page. Then the data is lost. This is a simple test code: <html> <head> <meta name="viewport" content="height=device-height, width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" /> </head> <body> <script> alert("1:" + localStorage.getItem("test")); localStorage.setItem("test", "123"); alert("2:" + localStorage.getItem("test")); </script> </body> As far as I understand the data should persist! Can anyone shed some light on this behavior? What should I do to get the persistence to work? Thanks! Tom.

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Locking database edit by key name

- by Will Glass

I need to prevent simultaneous edits to a database field. Users are executing a push operation on a structured data field, so I want to sequence the operations, not simply ignore one edit and take the second. Essentially I want to do synchronized(key name) { push value onto the database field } and set up the synchronized item so that only one operation on "key name" will occur at a time. (note: I'm simplifying, it's not always a simple push). A crude way to do this would be a global synchronization, but that bottlenecks the entire app. All I need to do is sequence two simultaneous writes with the same key, which is rare but annoying occurrence. This is a web-based java app, written with Spring (and using JPA/MySQL). The operation is triggered by a user web service call. (the root cause is when a user sends two simultaneous http requests with the same key). I've glanced through the Doug Lea/Josh Bloch/et al Concurrency in Action, but don't see an obvious solution. Still, this seems simple enough I feel there must be an elegant way to do this.

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jQuery code not executing when DOM is ready

- by Ben

I have written a simple jQuery script that changes the hash tag of a link. I do this because I am using IntenseDebate comments in Wordpress but the comment link still links replaced id of the old comments. I'm using jQuery so that if javascript is enabled, the user can click on the comments link and it will take them to the IntenseDebate comments. If its not enabled it will take them to the traditional comments (because IntenseDebate requires javascript to function). The issue I'm having lies in this script to change the hash tag at the end of the link. Currently the URL "someurl.com/#respond" but I need the script to change it to "someurl.com/#comments". What is happening is that the script doesn't work, however I believe my syntax is correct so I decided to try copying and pasting the code into Firebug's console and the code executed perfectly. I could see that the link I was trying to change was now correct, and I could click on it and it worked as I desired. So what I don't understand is why the code is not executing when it is supposed to. I am using $(document).ready() and I have other jQuery on the page that executes just fine. I even tested it on a simple HTML page away from all the problems that might be caused by Wordpress and I received the same result. Does anyone know why this might be happening? Here is my code (I am using noConflict because Wordpress makes use of other frameworks): jQuery.noConflict(); jQuery(document).ready(function($) { $("a[href$='respond']").each(function() { this.href = this.href.replace("respond", "comments"); }); })(jQuery); Thanks very much for your help!

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Require reasonably random results from an SQL SELECT query within a Joomla article (Cache enabled)

- by Shrinivas

Setup: Joomla website on LAMP stack I have a MySQL table containing some records, these are queried by a simple SELECT on the Joomla article, as pasted below. This specific Joomla website has Caching turned on in Joomla's Global Configuration. I need to randomize the order in which I display the resultset, each time the page is loaded. Regular php/mysql would offer me two approaches for this: 1. use 'order by RAND()' or any of a number of methods to allow a SELECT query to return reasonably random results. 2. once php gets the result from the SELECT into an array, shuffle the array to get a reasonably random order of array items. However, as this Joomla instance has Caching turned ON in its Global Configuration, either of the above approaches fails. The first time I load the page the order is randomized, however any further reloads do not cause the order to change, as the page is delivered from cache. The instant the Cache is disabled, both approaches (shuffle/order by rand) work perfectly. What am I missing? How do I override the Global Cache for this specific article? A very simple requirement, that is met by both php and mysql reasonably well, is blocked by the Joomla Cache that I cannot turn off. The php that returns results from the database. <pre> $db = JFactory::getDBO(); $select = "SELECT id FROM jos_mytable;"; //order by RAND() $db->setQuery($select); echo $db->getQuery(); //Show me the Query! $rows = $db->loadObjectList(); //shuffle($rows); foreach($rows as $row) { echo "$row->id"; }

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find consecutive nonzero values

- by thymeandspace

I am trying to write a simple MATLAB program that will find the first chain (more than 70) of consecutive nonzero values and return the starting value of that consecutive chain. I am working with movement data from a joystick and there are a few thousand rows of data with a mix of zeros and nonzero values before the actual trial begins (coming from subjects slightly moving the joystick before the trial actually started). I need to get rid of these rows before I can start analyzing the movement from the trials. I am sure this is a relatively simple thing to do so I was hoping someone could offer insight. Thank you in advance -Lilly EDIT: Here's what I tried: s = zeros(size(x1)); for i=2:length(x1) if(x1(i-1) ~= 0) s(i) = 1 + s(i-1); end end display(S); for a vector x1 which has a max chain of 72 but I dont know how to find the max chain and return its first value, so I know where to trim. I also really don't think this is the best strategy, since the max chain in my data will be tens of thousands of values. Thanks for helping me edit, Steve. :)

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Setting UITabBarItem title from UINavigationController?

- by fuzzygoat

I have setup a UITabBarController with two tabs, one is a simple UIViewController and the other is a UINavigationController using second UIViewController as its rootController to set up a UITableView. My question is with regard to naming the tabs (i.e. UITabBarItem) For the first tab (simple UIViewController) I have added the following (see below) to the controllers -init method. - (id)init { self = [super init]; if(self) { UITabBarItem *tabBarItem = [self tabBarItem]; [tabBarItem setTitle:@"ONE"]; } return self; } For the other tab I have added (see below) to the second controllers init (rootController). - (id)init { self = [super init]; if(self) { UITabBarItem *tabBarItem = [[self navigationController] tabBarItem]; [tabBarItem setTitle:@"TWO"]; } return self; } Am I setting the second tabBarItem title in the right place as currently it is not showing? EDIT: I can correctly set the UITabBarItem from within the AppDelegate when I first create the controllers, ready for adding to the UITabBarController. But I really wanted to do this in the individual controller -init methods for neatness. // UITabBarController UITabBarController *tempRoot = [[UITabBarController alloc] init]; [self setRootController:tempRoot]; [tempRoot release]; NSMutableArray *tabBarControllers = [[NSMutableArray alloc] init]; // UIViewController ONE MapController *mapController = [[MapController alloc] init]; [tabBarControllers addObject:mapController]; [mapController release]; // UITableView TWO TableController *rootTableController = [[TableController alloc] init]; UINavigationController *tempNavController = [[UINavigationController alloc] initWithRootViewController:rootTableController]; [rootTableController release]; [tabBarControllers addObject:tempNavController]; [tempNavController release]; [rootController setViewControllers:tabBarControllers]; [tabBarControllers release]; [window addSubview:[rootController view]]; [window makeKeyAndVisible];

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WCF publish/subscribe service, and ASP.NET MVC client

- by d3j4vu

I managed to develop a custom WCF service, using the publish / subscribe model, and hosted inside a managed windows service. Everything's working. I developed an interface as the service contract implementing a method definition marked as a non-one way operation contract (OperationContract(IsOneWay = false)]. This, to make possible returns an instance of a custom class derived from System.Web.Mvc.ActionResult. In the MVC app, event fires ok. It wraps inside an action method, (just the one defined in the interface), but, and this is my current problem, i believe that something relative to the execution context of the windows service (and the hosted wcf counterpart) blocks the execution of the action method in the MVC app. This is what i have until now (some pieces ripped off just to be more clear): /// Method definition for the contract's service. Maps to a MVC ActionMethod. [OperationContract(IsOneWay = false)] ActionResult Imagen(string data, CustomActionResult result); The class to hold an ActionResult derived class instance: public class ServiceEventArgsMvc : ServiceEventArgs { /// <summary> /// /// </summary> public CustomActionResult Result { get; set; } } And the code in the MVC client app: /// <summary> /// Just a simple class to hold an abstract ActionResult derived class instance. /// </summary> public ActionResult Image(string data, CustomActionResult result) { ViewData["data"] = data; return View(); } Ok. ActionMethod sucessfully executes...but when it's done (and usually expected obtain a reditection to a View named Image, like the action method), the WCF service throws a Timeout exception, making clear that he's still waiting for a response from the MVC client. The response never arrives, so the MVC app never finish his work (redirect to the "Image" view as expected). Any ideas?. Guess i'm missing something very simple, but i don't know what it could be. This is drivin' me nuts.

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Problems with Unity BuildUp Method

- by Voice

Hi everybody) I'm using Unity App Block for my project (version 1.2.0.0). I have a problem with Unity Container BuildUp method which I'm using for my ascx controls. Here is some code (that's pretty simple) public class BaseUserControl<T>:UserControl where T:class { protected override void OnInit(EventArgs e) { InjectDependencies(); base.OnInit(e); } protected virtual void InjectDependencies() { var context = HttpContext.Current; if (context == null) { return; } var accessor = context.ApplicationInstance as IContainerAccessor; if (accessor == null) { return; } var container = accessor.Container; if (container == null) { throw new InvalidOperationException("No Unity container found"); } container.BuildUp<T>(this as T); } } This method is called in base control for ascx controls in my solution. And here the property that should be injected in child control: [Dependency] private IStock Stock { get; set; } So after buildup Stock property is still empty. Resolve method works fine for IStock with the same container and configuration. I've tried buildup with simple test class with only one property IStock and got the same result. So what can be wrong with buildup?

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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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AsyncTask never finishes when other tasks are running

- by rebeccamaher

In my app, I show a menu screen immediately to the user and then use an AsyncTask to load some data from disk. Loading takes about 3 seconds if that's all the app had to do. When the user hits a menu option and the data hasn't loaded yet, a "Please wait, loading" screen appears. I have two problems: I recently added ads to my app and have found this is making my app hang sometimes because the AsyncTask never finishes loading. What seems to be happening is that the ad banner (I'm using admob and this happens when adsense ads are shown which admob do occasionally) is using resources by playing a simple animation and the AsyncTask never gets a chance to finish. I want to play a simple looping animation (e.g. making a view rotate) on my menu screen and this makes the AsyncTask take about 5 times longer to finish which renders the background loading pointless. How can I avoid situations where my background data never finishes loading or has such a low priority it takes a long time? I can't seem to find a way to increase the priority of an AsyncTask.

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c# Wrapper to native c++ code, wrapping a parameter which is a pointer to an array

- by mb300dturbo

Hi, I have the following simple DLL in c++ un-managed code; extern "C" __declspec(dllexport) void ArrayMultiplier(float (*pointerArray)[3], int scalar, int length); void ArrayMultiplier(float (*pointerArray)[3], int scalar, int length) { for (int i = 0 ; i < length ; length++) { for (int j = 0; j < 3; j++) { pointerArray[i][j] = pointerArray[i][j] * scalar; } } } I have tried writing the following wrapper function for the above in c#: [DllImport("sample.dll")] public static extern void ArrayMultiplier(ref float elements, int scalar, int length); where elements is a 2 dimentional 3x3 array: public float[][] elements = { new float[] {2,5,3}, new float [] {4,8,6}, new float [] {5,28,3} }; The code given above compiles, but the program crashes when the wrapper function is called: Wrapper.ArrayMultiplier(ref elements, scalar, length); Please help me here, and tell me whats wrong with the code above, or how a wrapper can be written for a simple c++ function: void SimpleFunction(float (*pointerToArray)[3]); Thank you all in advance

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How to make custom tab using jquery?

- by ALAN

i have following html, i want to make simple tab using jquery <td style="border-color: black; border-style: solid; border-width: 1px 0 1px 1px;"> <div id="cont-1-1"> My first tab content </div> <div id="cont-2-1"> My second tab content </div> </td> <td style="width: 30px"> <div id="tab-box"> <div style="height: 121px;"><img src="/Images/Tab1.png" /></div> <div style="border-left: 1px solid Black;"><img src="/Images/Tab2.png" /></div> <div style="border-left: 1px solid Black; height: 40px;"></div> </div> </td> </td> Where Tab1.Png and Tab2.Png are my tab headers and div id :cont-1-1 and 2-1 are tab content, i don't want to use any jquery plug-in for this, just need something simple when i click on tab,,hide and show contents thanks

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PHP OO vs Procedure with AJAX

- by vener

I currently have a AJAX heavy(almost everything) intranet webapp for a business. It is highly modularized(components and modules ala Joomla), with plenty of folders and files. ~ 80-100 different viewing pages (each very unique in it's own sense) on last count and will likely to increase in the near future. I based around the design around commands and screens, the client request a command and sends the required data and receives the data that is displayed via javascript on the screen. That said, there are generally two types of files, a display files with html, javascript, and a little php for templating. And also a php backend file with a single switch statement with actions such as, save, update and delete and maybe other function. There is very little code reuse. Recently, I have been adding an server sided undo function that requires me to reuse some code. So, I took the chance to try out OOP but I notice that some functions are so simple, that creating a class, retrieving all the data then update all the related rows on the database seems like overkill for a simple action as speed is quite critical. Also I noticed there is only one class in an entire file. So, what if the entire php is a class. So, between creating a class and methods, and using global variables and functions. Which is faster?

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Can I add a spring mvc filter using jetty with a jar file?

- by Juan Manuel

I have a simple web application disguised as a java application (as in, it's a .jar instead of a .war), and I'd like to use a filter for my requests. If it was a .war, I could initialize it with a WebAppContext and specify a web.xml file where I'd have my filter declaration like this <filter> <filter-name>myFilter</filter-name> <filter-class>MyFilterClass</filter-class> </filter> <filter-mapping> <filter-name>myFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> However, I'm using a simple Context to initialize my application with Spring. Server server = new Server(8082); Context root = new Context(server, "/", Context.SESSIONS); DispatcherServlet dispatcherServlet = new DispatcherServlet(); dispatcherServlet.setContextConfigLocation("classpath:application-context.xml"); root.addServlet(new ServletHolder(dispatcherServlet), "/*"); server.start(); Is there a way to programmatically specify filters for the spring servlet, without using a web.xml file?

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RIA Service - without database?

- by Heko

Helo! I need to write a RIA service to call Java webservices from Silverlight 3.0 app. I'm testing how stuff works and in my Web app I have a MyData class which has 2 properties (int ID, string Text): namespace SilverlightApplication1.Web { public class MyData { [Key] public int ID { get; set; } public string Text { get; set; } } } Then I wrote simple DomainService: [EnableClientAccess()] public class MyService : DomainService { public IQueryable<MyData> GetMyData(string Url) { // here I will call my WebService List<MyData> result = new List<MyData>(); result.Add(new MyData { ID = 1, Text = Url }); return result.AsQueryable(); } } } How can I get data into my SL app? Now I have this: namespace SilverlightApplication1 { public partial class MainPage : UserControl { public MainPage() { InitializeComponent(); MyContext context = new MyContext(); } } } I called and load but nothink worsk (exceptions, or nulls)... I had Invoke annotation but MyData is not TEntity and I can't use Strings or other simple types as well... :/ I'm reading and reading posts and nothing works like it should.. Any help would be really appreciated. Thank you!

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Has anyone ever successfully make index merge work for MySQL?

- by user198729

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Returning JSON from JavaScript to Python

- by Chris Lacy

I'm writing a simple App Engine app. I have a simple page that allows a user to move a marker on a Google map instance. Each time the user drops the marker, I want to return the long/lat to my Python app. function initialize() { ... // Init map var marker = new GMarker(center, {draggable: true}); GEvent.addListener(marker, "dragend", function() { // I want to return the marker.x/y to my app when this function is called .. }); } To my (admittedly limited) knowledge, I should be: 1). Returning a JSON structure with my required data in the listener callback above 2). In my webapp.RequestHandler Handler class, trying to retrieve the JSON structure during the post method. I would very much like to pass this JSOn data back to the app without causing a page reload (which is what has happened when I've used various post/form.submit methods so far). Can anyone provide me with some psuedo code or an example on how I might achieve what I'm after? Thanks.

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GUI for server-client program

- by sksingh73

I am making a server-client application in c++. In this i am also using shared memory & file read-write operations. my program is completely ready & i now wants to make a gui for it. someone suggested me to go for QT4, but when i tried it, i found i have to re-write 80% of the code because QT has got its own classes & variable. i don't want to do it. i want suggestions from you on this regard. my requirements for gui are very simple i.e there will be a main form, which will have two text boxes in which all messages being sent & received by client & server should be shown. there should be another lineedit box, through which i can send the messages to the other end server. I don't know how to make this gui. someone suggested tcl/tk, other suggested me use php/swig. i am not sure how to go about this. my only requirement is that i want to make this simple gui with minimum of changes in my code. THANX

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how to make it easy for users to register at my site?

- by rob

I want to make it dirt simple for users coming to my site to register so they can post comments, vote on things, etc. I would like for them to be able to use their facebook id, twitter id, yahoo mail id, gmail id, AIM id, msn id, or whatever else people are likely to have (not necessarily all of those, but the more the better). I want my mom to be able to do it in 30 seconds or less. (that is, no "enter your open id url here" type thing that would confuse her). I prefer they not have to pick a unique name, as that gets annoying as the site gets more users and it gets hard to find one that is unique. What is the best option here? I'm not quite sure about OpenId vs. OAuth, and whether there are other options. And I'd like it to be as simple for me, the developer, as possible (of course!). I don't want to spend forever learning some protocol, nor have to structure my whole app around this. It would be great if there was a site with sample code that is pretty easy to drop in. BTW, StackOverflow is a good example of a site that was easy for me to register for.

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CSS - Positioning images next to text

- by jpjoki

Hi, I'm doing a site in which images need to presented next to textual content - a sort of pseudo two-column layout, as the images and text come from a single html source. I've found quite a simple way to do this by putting the images as their own paragraphs and floating them. Would there still be a more simpler way (in regards to html) to do this without these extra paragraphs and by only attributing extra css to images? If the floated image is in the same paragraph than the text, then paragraphs with and without images would be different in width. EDIT: Basically, I'm looking for as simple HTML markup as possible to position images like this. The CSS can be complex ;) CSS: p { width: 500px; } p.image { float: right; width: 900px; } Current HTML: <p class="image"><img src="image.jpg" /></p> <p>Some text here.</p> Is the above possible with this HTML? <p><img src="image.jpg" /></p>

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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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zend-framework doctrine, and mvc pattern: what should connect data between models and forms?

- by Skirmantas

I am learning Zend Framework and Doctrine. I am wondering what is the best practice to connect forms to models and vice versa. I don't know where I should put my code. I have seen in Zendcast video tutorials where author creates methods like mapFormToRecord and mapRecordToForm in form class. Well I guess it is very handy when form is sophisticated and uses many records. Is it a good practice? I somehow believe that form-class should not need to know about data-records. And sometimes we might have model which is used in many forms. So It would be handy to have few functions in that model which would help to prepare data for forms. For example to give an array of id=name pairs so that it might be used in Zend_Form_Element_Select. However I would like to have a consistency. So I don't want to put this code nor in model nor in form because on different situations I act different. So only controller is what is left to deal it. However this will result in code duplication if one form will be used more than in one controller. Moreover controller gets bloated if form is not from the simple ones. Or maybe there is a consistent pattern in those data conversions between forms and models? I think that there is. At least in my simple cases. So maybe a separate class could be a solution? Where should I put such class and how should I name it? Another question: Zend_Form has validators and filter. Doctrine has validators and filters too. Which do we use and when? What is your way of dealing the connections between forms and models? (Sorry if it was hard for you to read my text. I don't have enough knowledge of English language to express myself freely)

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saveall not saving associated data

- by junior29101

I'm having a problem trying to save (update) some associated data. I've read about a million google returns, but nothing seems to be the solution. I'm at my wit's end and hope some kind soul here can help. I'm using 1.3.0-RC4, my database is in InnoDB. Course has many course_tees CourseTee belongs to course My controller function is pretty simple (I've made it as simple as possible): if(!empty($this-data)) $this-Course-saveAll($this-data); I've tried a lot of different variations of that $this-data['Course'], save($this-data), etc without luck. It saves the Course info, but not the CourseTee stuff. I don't get an error message. Since I don't know how many tees any given course will have, I generate the form inputs dynamically in a loop. $form-input('CourseTee.'.$i.'.teeName', array('error' = false, 'label' = false, 'value'=$data['course_tees'][$i]['teeName'])) The course inputs are simpler: $form-input('Course.hcp'.$j, array('error' = false, 'label' = false, 'class' = 'form_small_w', 'value'=$data['Course']['hcp'.$j])) And this is how my data is formatted: Array ( [Course] = Array ( [id] = 1028476 ... ) [CourseTee] = Array ( [0] = Array ( [key] = 636 [courseid] = 1028476 ... ) [1] = Array ( [key] = 637 [courseid] = 1028476 ... ) ... ) )

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Type-safe generic data structures in plain-old C?

- by Bradford Larsen

I have done far more C++ programming than "plain old C" programming. One thing I sorely miss when programming in plain C is type-safe generic data structures, which are provided in C++ via templates. For sake of concreteness, consider a generic singly linked list. In C++, it is a simple matter to define your own template class, and then instantiate it for the types you need. In C, I can think of a few ways of implementing a generic singly linked list: Write the linked list type(s) and supporting procedures once, using void pointers to go around the type system. Write preprocessor macros taking the necessary type names, etc, to generate a type-specific version of the data structure and supporting procedures. Use a more sophisticated, stand-alone tool to generate the code for the types you need. I don't like option 1, as it is subverts the type system, and would likely have worse performance than a specialized type-specific implementation. Using a uniform representation of the data structure for all types, and casting to/from void pointers, so far as I can see, necessitates an indirection that would be avoided by an implementation specialized for the element type. Option 2 doesn't require any extra tools, but it feels somewhat clunky, and could give bad compiler errors when used improperly. Option 3 could give better compiler error messages than option 2, as the specialized data structure code would reside in expanded form that could be opened in an editor and inspected by the programmer (as opposed to code generated by preprocessor macros). However, this option is the most heavyweight, a sort of "poor-man's templates". I have used this approach before, using a simple sed script to specialize a "templated" version of some C code. I would like to program my future "low-level" projects in C rather than C++, but have been frightened by the thought of rewriting common data structures for each specific type. What experience do people have with this issue? Are there good libraries of generic data structures and algorithms in C that do not go with Option 1 (i.e. casting to and from void pointers, which sacrifices type safety and adds a level of indirection)?

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