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  • Saving tree-structures in Databases

    - by Nina Null
    Hello everyone. I use Hibernate/Spring and a MySQL Database for my data management. Currently I display a tree-structure in a JTable. A tree can have several branches, in turn a branch can have several branches (up to nine levels) again, or having leaves. Lately I have performanceproblemes, as soon as I want to create new branches on deeper levels. At this time a branch has a foreign key to its parent. The domainobject has access to its parent by calling getParent(), which returns the parent-branch. The deeper the level, the longer it takes to create a new branch. Microbenchmark results for creating a new branch are like: Level 1: 32 ms. Level 3: 80 ms. Level 9: 232 ms. Obviously the level (which means the number of parents) is responsible for this. So I wanted to ask, if there are any appendages to work around this kind of problem. I don’t understand why Hibernate needs to know about the whole object tree (all parents until the root) while creating a new branch. But as far as I know this can be the only reason for the delay while creating a new branch, because a branch doesn’t have any other relations to any other objects. I would be very thankful for any workarounds or suggestions. greets, jambusa

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  • Hibernate: Walk millions of rows and don't leak memory

    - by Autocracy
    The below code functions, but Hibernate never lets go of its grip of any object. Calling session.clear() causes exceptions regarding fetching a joined class, and calling session.evict(currentObject) before retrieving the next object also fails to free the memory. Eventually I exhaust my heap space. Checking my heap dumps, StatefulPersistenceContext is the garbage collector's root for all references pointing to my objects. public class CriteriaReportSource implements JRDataSource { private ScrollableResults sr; private Object currentObject; private Criteria c; private static final int scrollSize = 10; private int offset = 1; public CriteriaReportSource(Criteria c) { this.c = c; advanceScroll(); } private void advanceScroll() { // ((Session) Main.em.getDelegate()).clear(); this.sr = c.setFirstResult(offset) .setMaxResults(scrollSize) .scroll(ScrollMode.FORWARD_ONLY); offset += scrollSize; } public boolean next() { if (sr.next()) { currentObject = sr.get(0); if (sr.isLast()) { advanceScroll(); } return true; } return false; } public Object getFieldValue(JRField jrf) throws JRException { Object retVal = null; if(currentObject == null) { return null; } try { retVal = PropertyUtils.getProperty(currentObject, jrf.getName()); } catch (Exception ex) { Logger.getLogger(CriteriaReportSource.class.getName()).log(Level.SEVERE, null, ex); } return retVal; } }

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  • After I apply custom logic, next UI action crashes my app.

    - by DanF
    I've got an team (eveningRoster) that I'm making a button add employees to. The team is really a relationship to that night's event, but it's represented with an AC. I wanted to make sure an employee did not belong to the team before it adds, so I added a method to MyDocument to check first. It seems to work, the error logs complete, but after I've added a member, the next time I click anything, the program crashes. Any guesses why? Here's the code: -(IBAction)playsTonight:(id)sender { NSArray *selection = [fullRoster selectedObjects]; NSArray *existing = [eveningRoster arrangedObjects]; //Result will be within each loop. BOOL result; //noDuplicates will stay YES until a duplicate is found. BOOL noDuplicates = YES; //For the loop: int count; for (count = 0; count < [selection count]; count++){ result = [existing containsObject:[selection objectAtIndex:count]]; if (result == YES){ NSLog(@"Duplicate found!"); noDuplicates = NO; } } if (noDuplicates == YES){ [eveningRoster addObjects:[fullRoster selectedObjects]]; NSLog(@"selected objects added."); [eveningTable reloadData]; NSLog(@"Table reloaded."); } [selection release]; [existing release]; return; }

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  • How do I get my Flash CS4 buttons to direct the user to another URL?

    - by goldenfeelings
    My apologies if this has been fully addressed before, but I've read through several other threads and still can't seem to get my file to work. My actionscript code is at the bottom of this message. I created it using instructions from the Adobe website: http://help.adobe.com/en_US/ActionScript/3.0_ProgrammingAS3/WS5b3ccc516d4fbf351e63e3d118a9b90204-7fd7.html I believe I have all of my objects set to the correct type of symbol (button) and all of my instances are named appropriately (see screenshot here: www.footprintsfamilyphoto.com/wp-content/themes/Footprints/images/flash_buttonissue.jpg) Action Script here. Let me know if you have suggestions! (Note: I am very new to Flash): stop (); function families(event:MouseEvent):void { var targetURL:URLRequest = new URLRequest("http://www.footprintsfamilyphoto.com/portfolio/families"); navigateToURL(targetURL); } bc_btn1.addEventListener(MouseEvent.CLICK, families); bc_btn2.addEventListener(MouseEvent.CLICK, families); function families(event:MouseEvent):void { var targetURL:URLRequest = new URLRequest("http://www.footprintsfamilyphoto.com/portfolio/families"); navigateToURL(targetURL); } f_btn1.addEventListener(MouseEvent.CLICK, families); f_btn2.addEventListener(MouseEvent.CLICK, families); function families(event:MouseEvent):void { var targetURL:URLRequest = new URLRequest("http://www.footprintsfamilyphoto.com/portfolio/families"); navigateToURL(targetURL); } cw_btn1.addEventListener(MouseEvent.CLICK, families); cw_btn2.addEventListener(MouseEvent.CLICK, families);

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  • cant calculate width of elements

    - by Kein
    I try to get width of dom objects: function resizeArea(){ var width = 0; area.children().each(function(i){ alert(this.offsetWidth); width += this.offsetWidth; }); area.css('width', width); } In get results: Chrome: 800 Opera: 708 FF: 783 IE: 714 But if see it in firebug, dragonfly and other debuggers i see correct 908px. I don't know where porblem. I run this fun after domloaded. Here is HTML and css of block: <div class="scroll_area" id="scroll"> <div class="area" id="area"> <div class="category"> [..] </div> </div> </div> <style> #scroll { position:realtive; width: 800px, heght: 400px; } #area { position:absolute; left: 0; top: 0; } #area .category, #area .category .text, #area .category .image{ width: 200px } </style> And that interesting. This function later work correctly, only at first run, for first calculating.

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  • Java/JAXB: Accessing property of object in a list

    - by Mark Lewis
    Hello Using JAXB I've created a series of classes which represent my XML schema. Validating against the schema an XML file has thus become a 'tree' of java objects representing the XML. Now I'd like to access, delete and add an object of one the created types in my tree. If I've got classes' methods arranged like this: RootType class has: public List<FQType> getFq() { // and setter return fq; } FQType class has: public RemapType getRemap() { // and setter return remap; } RemapType class has: public String getSource() { // and setter return source; } What's the most concise way to code reading and writing of the 'source' member of a RemapType instance in an FQType instance with, say, fqtypeID=1, in an array of type RootType (in which RootType instances also each have rootID)? Currently I'm using a for loop Iterator in which is an if rootID = mySelectedRootID. In the if I nest a second for loop Iterator over the contained FQType instances and in that a second if fqTypeID = mySelectedFQTypeID. IE for loop iterator/if statement pairs to recognise the object of desire. With all the bells and whistles this way is nearly 15 lines of code to access a data type - can I do this in one line? Thanks

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  • What's the order of execution in property setters when using IDataErrorInfo?

    - by Benny Jobigan
    Situation: Many times with WPF, we use INotifyPropertyChanged and IDataErrorInfo to enable binding and validation on our data objects. I've got a lot of properties that look like this: public SomeObject SomeData { get { return _SomeData; } set { _SomeData = value; OnPropertyChanged("SomeData"); } } Of course, I have an appropriate overridden IDataErrorInfo.this[] in my class to do validation. Question: In a binding situation, when does the validation code get executed? When is the property set? When is the setter code executed? What if the validation fails? For example: User enters new data. Binding writes data to property. Property set method is executed. Binding checks this[] for validation. If the data is invalid, the binding sets the property back to the old value. Property set method is executed again. This is important if you are adding "hooks" into the set method, like: public string PathToFile { get { return _PathToFile; } set { if (_PathToFile != value && // prevent unnecessary actions OnPathToFileChanging(value)) // allow subclasses to do something or stop the setter { _PathToFile = value; OnPathToFileChanged(); // allow subclasses to do something afterwards OnPropertyChanged("PathToFile"); } } }

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  • get_by_id method on Model classes in Google App Engine Datastore

    - by tarn
    I'm unable to workout how you can get objects from the Google App Engine Datastore using get_by_id. Here is the model from google.appengine.ext import db class Address(db.Model): description = db.StringProperty(multiline=True) latitude = db.FloatProperty() longitdue = db.FloatProperty() date = db.DateTimeProperty(auto_now_add=True) I can create them, put them, and retrieve them with gql. address = Address() address.description = self.request.get('name') address.latitude = float(self.request.get('latitude')) address.longitude = float(self.request.get('longitude')) address.put() A saved address has values for >> address.key() aglndWVzdGJvb2tyDQsSB0FkZHJlc3MYDQw >> address.key().id() 14 I can find them using the key from google.appengine.ext import db address = db.get('aglndWVzdGJvb2tyDQsSB0FkZHJlc3MYDQw') But can't find them by id >> from google.appengine.ext import db >> address = db.Model.get_by_id(14) The address is None, when I try >> Address.get_by_id(14) AttributeError: type object 'Address' has no attribute 'get_by_id' How can I find by id? EDIT: It turns out I'm an idiot and was trying find an Address Model in a function called Address. Thanks for your answers, I've marked Brandon as the correct answer as he got in first and demonstrated it should all work.

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  • Problems migrating databinding in VB.NET from Winforms to ASP.NET 2.0

    - by David
    And this was supposed to be so easy... I have existing business and data access layers that handle the retrieval and update of the data in question. These work great with the existing Winforms application (.Net V2.0) Now, in trying to write a new web-based UI, I'm running into all sorts of problems (last time I wrote asp.net code was in 1.1). Specifically, I can't data bind a text box to a business object. Oh, sure there's the ObjectDataSource but that wants to know how to do CRUD operations on the data. What I'm looking for is something that acts like the 'classic' binding objects so that, in my code, it's as simple as retrieving the object and doing a a refresh. The data component like FormView and DetailsView are so generic-looking that it's ridiculous. The existing application would have tabbed dialogs, text boxes grouped by panels, etc. On top of that, I have a directive to use master pages and unless one control causes it, I can't seem to get the content section to expand. I can't just put a text box 'below' the bottom of "Content1" and have it resize the content section - which gives me the same results as an earlier question I posted when the footer wasn't being 'pushed down' - relative position solved that but doesn't seem to solve it with placing small text boxes in the area. What I want is fairly simple. Something like: bindingobject.datasource = businessdataobject bindingobject.refresh ...and have the text boxes refresh with the new values. Likewise to have 'businessdataobject' properties updated as the user enters new data. I was able to do this with the GridView (grdRequests.DataSource = lstRequests) by making a list of asp:BoundField tags inside the collection of the GridView. Am I tilting at windmills here?

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  • App hosting Report Viewer crashes on exit after export

    - by Paul Sasik
    We have a .NET Winforms application that hosts the Crystal Reports Viewer control (Version XI). It works well for the most part but when an export of data from the viewer is performed the application will crash on exit and in unmanaged code. The error message is not very useful and just says that an incorrect memory location was accessed. No other info such a specific DLL etc. is provided. This only happens after the viewer is used to export a report to CSV, XML etc. My guess is that at some point in the export process Crystal creates a resource that attempts an action on shut down to a parent window (perhaps) that no longer exists. I've seen a number of memory leak and shut down issues with Crystal but this one's new. Has anyone seen it and come up with a workaround or has ideas for workarounds? So far we've tried explicitly disposing of all crystal-related objects, setting to null and even setting a Thread.Sleep cycle on shut down to "give Crystal time to clean up." Update: The crash happens only on shut down (so not immediate) All export formats work All export files are created properly CR is installed on the same machine as the hosting .NET app not sure about exporting from the IDE... is that even possible?

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  • systematizing error codes for a web app in php?

    - by user151841
    I'm working on a class-based php web app. I have some places where objects are interacting, and I have certain situations where I'm using error codes to communicate to the end user -- typically when form values are missing or invalid. These are situations where exceptions are unwarranted ( and I'm not sure I could avoid the situations with exceptions anyways). In one object, I have some 20 code numbers, each of which correspond to a user-facing message, and a admin/developer-facing message, so both parties know what's going on. Now that I've worked over the code several times, I find that it's difficult to quickly figure out what code numbers in the series I've already used, so I accidentally create conflicting code numbers. For instance, I just did that today with 12, 13, 14 and 15. How can I better organize this so I don't create conflicting error codes? Should I create one singleton class, errorCodes, that has a master list of all error codes for all classes, systematizing them across the whole web app? Or should each object have its own set of error codes, when appropriate, and I just keep a list in the commentary of the object, to use and update that as I go along?

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  • How to close all tabs in Safari using AppleScript?

    - by Form
    I have made a very simple AppleScript to close all tabs in Safari. The problem is, it works, but not completely. Here's the code: tell application "Safari" repeat with aWindow in windows repeat with aTab in tabs of aWindow aTab close end repeat end repeat end tell I've also tried this script: tell application "Safari" repeat with i from 0 to the number of items in windows set aWindow to item i of windows repeat with j from 0 to the number of tabs in aWindow set aTab to item j of tabs of aWindow aTab close end repeat end repeat end tell ... but it does not work either. I tried that on my system (MacBook Pro jan 2008), as well as on a Mac Pro G5 under Tiger and the script fails on both, albeit with a much less descriptive error on Tiger. The problem is that only a couple of tabs are closed. Running the script a few times closes a few tab each time until none is left, but always fails with the same error after closing a few tabs. Under Leopard I get an out of bounds error. Since I am using fast enumeration (not using "repeat from 0 to number of items in windows") I don't see how I can get an out of bounds error with this... My goal is to use the Cocoa Scripting Bridge to close tabs in Safari from my Objective-C Cocoa application but the Scripting Bridge fails in the same manner. The non-deletable tabs show as NULL in the Xcode debugger, while the other tabs are valid objects from which I can get values back (such as their title). In fact I tried with the Scripting Bridge first then told myself why not try this directly in AppleScript and I was surprised to see the same results. I must have a glaring omission or something in there... (seems like a bug in Safari AppleScript support to me... :S) I've used repeat loops and Obj-C 2.0 fast enumeration to iterate through collections before with zero problems, so I really don't see what's wrong here. Anyone can help? Thanks in advance!

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  • Displaying Flex Object References

    - by Pie21
    I have a bit of a memory leak issue in my Flex application, and the short version of my question is: is there any way (in AcitonScript 3) to find all live references to a given object? What I have is a number of views with presentation models behind each of them (using Swiz). The views of interest are children of a TabNavigator, so when I close the tab, the view is removed from the stage. When the view is removed from the stage, Swiz sets the model reference in the view to null, as it should. I also removeAllChildren() from the view. However when profiling the application, when I do this and run a GC, neither the view nor the presentation model are freed (though both set their references to each other to null). One model object used by the view (not a presenter, though) IS freed, so it's not completely broken. I've only just started profiling today (firmly believing in not optimising too early), so I imagine there's some kind of reference floating around somewhere, but I can't see where, and what would be super helpful would be the ability to debug and see a list of objects that reference the target object. Is this at all possible, and if not natively, is there some light-weight way to code this into future apps for debugging purposes? Cheers.

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  • Classic ASP application-wide initializations and object caching

    - by slack3r
    In classic ASP (which I am forced to use), I have a few factory functions, that is, functions that return classes. I use JScript. In one include file I use these factory functions to create some classes that are used throughout the application. This include file is included with the #include directive in all pages. These factory functions do some "heavy lifting" and I don't want them to be executed on every page load. So, to make this clear I have something like this: // factory.inc function make_class(arg1, arg2) { function klass() { //... } // ... Some heavy stuff return klass; } // init.inc, included everywhere <!-- #include FILE="factory.inc" --> // ... MyClass1 = make_class(myarg01, myarg02); MyClass2 = make_class(myarg11, myarg12); //... How can I achieve the same effect without calling make_class on every page load? I know that I can't cache the classes in the Application object I can't use the Application_OnStart hook in Global.asa I could probably create a scripting component, but I really don't want to do that So, is there something else I can do? Maybe some way to achieve caching of these classes, which are really objects in JScript. PS: [further clarification] In the above code "heavy stuff" is not so heavy, but I just want to know if there's a way to avoid it being executed all the time. It reads database meta information, builds a table of the primary keys in the database and another table that resolves strings to classes, etc.

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  • Need a workaround to filter on related model and aggregated fields in Django

    - by parxier
    I opened a ticket for this problem. In a nutshell here is my model: class Plan(models.Model): cap = models.IntegerField() class Phone(models.Model): plan = models.ForeignKey(Plan, related_name='phones') class Call(models.Model): phone = models.ForeignKey(Phone, related_name='calls') cost = models.IntegerField() I want to run a query like this one: Phone.objects.annotate(total_cost=Sum('calls__cost')).filter(total_cost__gte=0.5*F('plan__cap')) Unfortunately Django generates bad SQL: SELECT "app_phone"."id", "app_phone"."plan_id", SUM("app_call"."cost") AS "total_cost" FROM "app_phone" INNER JOIN "app_plan" ON ("app_phone"."plan_id" = "app_plan"."id") LEFT OUTER JOIN "app_call" ON ("app_phone"."id" = "app_call"."phone_id") GROUP BY "app_phone"."id", "app_phone"."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan"."cap" and errors with: ProgrammingError: column "app_plan.cap" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan".... Is there any workaround apart from running raw SQL?

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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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  • Java downcasting and is-A has-A relationship

    - by msharma
    HI, I have a down casting question, I am a bit rusty in this area. I have 2 clasess like this: class A{ int i; String j ; //Getters and setters} class B extends A{ String k; //getter and setter} I have a method like this, in a Utility helper class: public static A converts(C c){} Where C are objects that are retireved from the database and then converted. The problem is I want to call the above method by passing in a 'C' and getting back B. So I tried this: B bClasss = (B) Utility.converts(c); So even though the above method returns A I tried to downcast it to B, but I get a runtime ClassCastException. Is there really no way around this? DO I have to write a separate converts() method which returns a B class type? If I declare my class B like: class B { String k; A a;} // So instead of extending A it has-a A, getter and setters also then I can call my existing method like this: b.setA(Utility.converts(c) ); This way I can reuse the existing method, even though the extends relationship makes more sense. What should I do? Any help much appreciated. Thanks.

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  • How to change value inside a JSON string.

    - by Jeremy Roy
    I have a JSON string array of objects like this. [{"id":"4","rank":"adm","title":"title 1"}, {"id":"2","rank":"mod","title":"title 2"}, {"id":"5","rank":"das","title":"title 3"}, {"id":"1","rank":"usr","title":"title 4"}, {"id":"3","rank":"ref","title":"title 5"}] I want to change the title value of it, once the id is matching. So if my variable myID is 5, I want to change the title "title 5" to new title, and so on. And then I get the new JSON array to $("#rangArray").val(jsonStr); Something like $.each(jsonStr, function(k,v) { if (v==myID) { this.title='new title'; $("#myTextArea").val(jsonStr); } }); Here is the full code. $('img.delete').click(function() { var deltid = $(this).attr("id").split('_'); var newID = deltid[1]; var jsonStr = JSON.stringify(myArray); $.each(jsonStr, function(k,v) { if (v==newID) { // how to change the title jsonStr[k].title = 'new title'; alert(jsonStr); $("#rangArray").val(jsonStr); } }); }); The above is not working. Any help please?

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  • [jscript] Good (better) substition for setInterval or setTimeout

    - by riffnl
    I've got a masterpage with some nice UI (jQuery) features. One of these options is interefering with my embedded YouTube (or other alike-) objects. On each, in this case, setInterval event the embedded video stops displaying new frames (for like a second). More detail: I've got a "polaroid" gallery (in the header) with only 5 100x100 images in it (test: preloading has no effect on performance) and my gallery will show or hide them (fade-in / fade-out) after a period of time. (test: non-animated display:hide or display:block has no effect on performance). After some testing and I've come to the conclusion that it isn't the "animated" showing or hiding of the pictures, but it's the interval itself (- since altering to display:hide or block had the same result). Perhaps it is my "gallery" "function" on itself ... function poladroid() { if (!galleryHasFocus) { if (galleryMax >= 0) { galleryCurrent++; if (galleryCurrent > galleryMax) { galleryCurrent = 0; showPictures = !showPictures; } if (showPictures) { $('#pic-' + galleryCurrent.toString()).show("slow"); } else { $('#pic-' + galleryCurrent.toString()).hide("slow"); } } } if (!intervalSet) { window.setInterval("poladroid()", 3000); intervalSet = true; } } It's not like my function is doing really awkward stuff is it? So, I was thinking I needed a more "loose" interval function.. but is there an option for it?

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  • d3: Coloring Multiple Lines from Nested Data

    - by diet_coke
    I'm currently assembling some line graphs with circles at the datapoints from arrays of JSON objects formatted like so: var data = [{ "name": "metric1", "datapoints": [ [10.0, 1333519140], [48.0, 1333519200] ] }, { "name": "metric2", "datapoints": [ [48.0, 1333519200], [12.0, 1333519260] ] }] I want to have a color for each metric, so I'm trying to color them based on the index of the object within the array data. The code I have currently for just placing the circles looks like: // We bind an svg group to each metric. var metric_groups = this.vis.selectAll("g.metric_group") .data(data).enter() .append("g") .attr("class", "metric_group"); // Then bind a circle for each datapoint. var circles = metric_groups.selectAll("circle") .data(function(d) { return d.datapoints; }); circles.enter().append("circle") .attr("r", 3.5); Now if I change that last bit to something like: circles.enter().append("circle") .attr("r", 3.5); .style("fill", function(d,i) { return i%2 ? "red" : "blue"; } I get alternating red and blue circles, as could be expected. Taking some advice from Nested Selections : 'Nesting and Index', I tried: circles.enter().append("circle") .attr("r", 3.5); .style("fill", function(d,i,j) { return j%2 ? "red" : "blue"; } Which doesn't work (j is undefined), presumably because we are in the named property datapoints, rather than an array element. How might I go about doing the coloring that I want without changing my data structure? Thanks!

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  • unable to set fields of a collection-property elements after changing their order (elements becoming

    - by Jaroslav Záruba
    Hello I want to change order of objects in a collection, and then to access+modify fields of those items. Unfortunately the items somehow become 'deleted'. This is what I do... if(someCondition) { MainEvent mainEvent = pm.getObjectById(MainEvent.class, mainEventKey); /* * events in the original order * MainEvent.subEvents field is not in default fetch group, * therefore I also tried to add the named group into the * persistenceManeger fetch plan, no difference * (mainEvent is not instance of the Event sub/class BTW) */ List<Event> subEvents = mainEvent.getSubEvents(); // re-arrange the events according to keysOrdered { Map<Key, Event> eventMap = new HashMap<Key, Event>(); for(Event event : subEvents) eventMap.put(event.getKey(), event); List<Event> eventsOrdered = new LinkedList<Event>(); for(Key eventKey : keysOrdered) eventsOrdered.add(eventMap.put(eventKey, eventMap.get(eventKey))); // } // put the re-arranged items back into the collection property { subEvents.clear(); subEvents.addAll(eventsOrdered); // } pm.makePersistent(mainEvent); eventsOrdered = subEvents; } else eventsOrdered = getEventsUsingAlternateApproach(); /* * so by now the mainEvent variable does not exist; * could it be this lead the persistence manager to mark * my events as abandoned/obsolete/invalid/deleted...? */ for(Event event : eventsOrdered) event.setDate(new Date()); // -> "Cannot write fields to a deleted object" What am I doing wrong please?

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  • Why is JavaMail Transport.send() a static method?

    - by skiphoppy
    I'm revising code I did not write that uses JavaMail, and having a little trouble understanding why the JavaMail API is designed the way it is. I have the feeling that if I understood, I could be doing a better job. We call: transport = session.getTransport("smtp"); transport.connect(hostName, port, user, password); So why is Eclipse warning me that this: transport.send(message, message.getAllRecipients()); is a call to a static method? Why am I getting a Transport object and providing settings that are specific to it if I can't use that object to send the message? How does the Transport class even know what server and other settings to use to send the message? It's working fine, which is hard to believe. What if I had instantiated Transport objects for two different servers; how would it know which one to use? In the course of writing this question, I've discovered that I should really be calling: transport.sendMessage(message, message.getAllRecipients()); So what is the purpose of the static Transport.send() method? Is this just poor design, or is there a reason it is this way?

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  • How do you deserialize a collection with child collections?

    - by Stuart Helwig
    I have a collection of custom entity objects one property of which is an ArrayList of byte arrays. The custom entity is serializable and the collection property is marked with the following attributes: [XmlArray("Images"), XmlArrayItem("Image",typeof(byte[]))] So I serialize a collection of these custom entities and pass them to a web service, as a string. The web service receives the string and byte array in tact, The following code then attempts to deserialize the collection - back into custom entities for processing... XmlSerializer ser = new XmlSerializer(typeof(List<myCustomEntity>)); StringReader reader = new StringReader(xmlStringPassedToWS); List<myCustomEntity> entities = (List<myCustomEntity>)ser.Deserialize(reader); foreach (myCustomEntity e in entities) { // ...do some stuff... foreach (myChildCollection c in entities.ChildCollection { // .. do some more stuff.... } } I've checked the XML resulting from the initial serialization and it does contain byte array - the child collection, as does the StringReader built above. After the deserialization process, the resulting collection of custom entites is fine, except that each object in the collection does not contain any items in its child collection. (i.e. it doesn't get to "...do some more stuff..." above. Can someone please explain what I am doing wrong? Is it possible to serialize ArrayLists within a generic collection of custom entities?

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  • PHP Exceptions in Classes

    - by mike condiff
    I'm writing a web application (PHP) for my friend and have decided to use my limited OOP training from Java. My question is what is the best way to note in my class/application that specific critical things failed without actually breaking my page. Currently my problem is I have an Object "SummerCamper" which takes a camper_id as it's argument to load all of the necessary data into the object from the database. Say someone specifies a camper_id in the querystring that does not exist, I pass it to my objects constructor and the load fails. Currently I don't see a way for me to just return false from the constructor. I have read I could possibly do this with Exceptions, throwing an exception if no records are found in the database or if some sort of validation fails on input of the camper_id from the application etc. However, I have not really found a great way to alert my program that the Object Load has failed. I tried returning false from within the CATCH but the Object still persists in my php page. I do understand I could put a variable $is_valid = false if the load fails and then check the Object using a get method but I think there may be better ways. What is the best way of achieving the essential termination of an object if a load fails? Should I load data into the object from outside the constructor? Is there some osrt of design pattern that I should look into? Any help would be appreciated.

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  • Components don't show in custom JPanel/JComponent

    - by Bart van Heukelom
    I've created a custom swing component. I can see it (the grid from the paint method is drawn), but the buttons that are added (verified by println) aren't shown. What am I doing wrong? Background information: I'm trying to build a tree of visible objects like the Flash/AS3 display list. public class MapPanel extends JComponent { // or extends JPanel, same effect private static final long serialVersionUID = 4844990579260312742L; public MapPanel(ShapeMap map) { setBackground(Color.LIGHT_GRAY); setPreferredSize(new Dimension(1000,1000)); setLayout(null); for (Layer l : map.getLayers()) { // LayerView layerView = new LayerView(l); // add(layerView); System.out.println(l); JButton test = new JButton(l.getName()); add(test); validate(); } } @Override protected void paintComponent(Graphics g) { // necessary? super.paintComponent(g); // background g.setColor(getBackground()); g.fillRect(0, 0, getWidth(), getHeight()); // grid g.setColor(Color.GRAY); for (double x = 0; x < getWidth(); x += 10) { g.drawLine((int)x, 0, (int)x, getHeight()); } for (double y = 0; y < getHeight(); y += 10) { g.drawLine(0, (int)y, getWidth(), (int)y); } } }

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