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  • What are the disadvantages of self-encapsulation?

    - by Dave Jarvis
    Background Tony Hoare's billion dollar mistake was the invention of null. Subsequently, a lot of code has become riddled with null pointer exceptions (segfaults) when software developers try to use (dereference) uninitialized variables. In 1989, Wirfs-Brock and Wikerson wrote: Direct references to variables severely limit the ability of programmers to re?ne existing classes. The programming conventions described here structure the use of variables to promote reusable designs. We encourage users of all object-oriented languages to follow these conventions. Additionally, we strongly urge designers of object-oriented languages to consider the effects of unrestricted variable references on reusability. Problem A lot of software, especially in Java, but likely in C# and C++, often uses the following pattern: public class SomeClass { private String someAttribute; public SomeClass() { this.someAttribute = "Some Value"; } public void someMethod() { if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { return this.someAttribute; } } Sometimes a band-aid solution is used by checking for null throughout the code base: public void someMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void anotherMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Default Value" ) ) { // do something... } } The band-aid does not always avoid the null pointer problem: a race condition exists. The race condition is mitigated using: public void anotherMethod() { String someAttribute = this.someAttribute; assert someAttribute != null; if( someAttribute.equals( "Some Default Value" ) ) { // do something... } } Yet that requires two statements (assignment to local copy and check for null) every time a class-scoped variable is used to ensure it is valid. Self-Encapsulation Ken Auer's Reusability Through Self-Encapsulation (Pattern Languages of Program Design, Addison Wesley, New York, pp. 505-516, 1994) advocated self-encapsulation combined with lazy initialization. The result, in Java, would resemble: public class SomeClass { private String someAttribute; public SomeClass() { setAttribute( "Some Value" ); } public void someMethod() { if( getAttribute().equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { String someAttribute = this.someAttribute; if( someAttribute == null ) { setAttribute( createDefaultValue() ); } return someAttribute; } protected String createDefaultValue() { return "Some Default Value"; } } All duplicate checks for null are superfluous: getAttribute() ensures the value is never null at a single location within the containing class. Efficiency arguments should be fairly moot -- modern compilers and virtual machines can inline the code when possible. As long as variables are never referenced directly, this also allows for proper application of the Open-Closed Principle. Question What are the disadvantages of self-encapsulation, if any? (Ideally, I would like to see references to studies that contrast the robustness of similarly complex systems that use and don't use self-encapsulation, as this strikes me as a fairly straightforward testable hypothesis.)

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  • why are read only form fields in django a bad idea?

    - by jamida
    I've been looking for a way to create a read-only form field and every article I've found on the subject comes with a statement that "this is a bad idea". Now for an individual form, I can understand that there are other ways to solve the problem, but using a read only form field in a modelformset seems like a completely natural idea. Consider a teacher grade book application where the teacher would like to be able to enter all the students' (note the plural students) grades with a single SUBMIT. A modelformset could iterate over all the student-grades in such a way that the student name is read-only and the grade is the editable field. I like the power and convenience of the error checking and error reporting you get with a modelformset but leaving the student name editable in such a formset is crazy. Since the expert django consensus is that read-only form fields are a bad idea, I was wondering what the standard django best practice is for the example student-grade example above?

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  • How do I Reset the Values in My ASP.NET Fields?

    - by Giffyguy
    The current form is here. It is not complete, and only a couple options will work. Select "Image CD" and then any resolution and click "Add to Order." The order will be recorded on the server-side, but on the client-side I need to reset the product drop-down to "{select}" so that the user will know that they need to select another product. This is consistant with the idea that the sub-selections disappear. I don't know whether I should be using ASP postback or standard form submittal, and most of the fields need to be reset when the user adds an item to the order.

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  • Working out global tab order algorithmically?

    - by Mrgreen
    We have a proprietry system where we can configure fields on indiviual forms. However these fields have a global tab order (we cannot specify for a specific form). We have a bunch of forms (35 in total) which share a lot of different fields. Each form has a specific tab/edit order that needs to be configured. Example: Form 1 has fields A,B,C,D in that order. Form 2 has fields E,F,G,A in that order. Form 3 has fields E,B,H,I in that order. The global tab orders would be E,F,G,A,B,C,D,H,I Notice how A needs to come before B yet after G. Is there any easy way to work this out using the tab order lists for each form? I need to merge this tab order information into a single global tab order list. I have over 200 fields in total and it is near impossible to do by hand.

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  • NerdDinner form validation DataAnnotations ERROR in MVC2 when a form field is left blank.

    - by Edward Burns
    Platform: Windows 7 Ultimate IDE: Visual Studio 2010 Ultimate Web Environment: ASP.NET MVC 2 Database: SQL Server 2008 R2 Express Data Access: Entity Framework 4 Form Validation: DataAnnotations Sample App: NerdDinner from Wrox Pro ASP.NET MVC 2 Book: Wrox Professional MVC 2 Problem with Chapter 1 - Section: "Integrating Validation and Business Rule Logic with Model Classes" (pages 33 to 35) ERROR Synopsis: NerdDinner form validation ERROR with DataAnnotations and db nulls. DataAnnotations in sample code does not work when the database fields are set to not allow nulls. ERROR occurs with the code from the book and with the sample code downloaded from codeplex. Help! I'm really frustrated by this!! I can't believe something so simple just doesn't work??? Steps to reproduce ERROR: Set Database fields to not allow NULLs (See Picture) Set NerdDinnerEntityModel Dinner class fields' Nullable property to false (See Picture) Add DataAnnotations for Dinner_Validation class (CODE A) Create Dinner repository class (CODE B) Add CREATE action to DinnerController (CODE C) This is blank form before posting (See Picture) This null ERROR occurs when posting a blank form which should be intercepted by the Dinner_Validation class DataAnnotations. Note ERROR message says that "This property cannot be set to a null value. WTH??? (See Picture) The next ERROR occurs during the edit process. Here is the Edit controller action (CODE D) This is the "Edit" form with intentionally wrong input to test Dinner Validation DataAnnotations (See Picture) The ERROR occurs again when posting the edit form with blank form fields. The post request should be intercepted by the Dinner_Validation class DataAnnotations. Same null entry error. WTH??? (See Picture) See screen shots at: http://www.intermedia4web.com/temp/nerdDinner/StackOverflowNerdDinnerQuestionshort.png CODE A: [MetadataType(typeof(Dinner_Validation))] public partial class Dinner { } [Bind(Include = "Title, EventDate, Description, Address, Country, ContactPhone, Latitude, Longitude")] public class Dinner_Validation { [Required(ErrorMessage = "Title is required")] [StringLength(50, ErrorMessage = "Title may not be longer than 50 characters")] public string Title { get; set; } [Required(ErrorMessage = "Description is required")] [StringLength(265, ErrorMessage = "Description must be 256 characters or less")] public string Description { get; set; } [Required(ErrorMessage="Event date is required")] public DateTime EventDate { get; set; } [Required(ErrorMessage = "Address is required")] public string Address { get; set; } [Required(ErrorMessage = "Country is required")] public string Country { get; set; } [Required(ErrorMessage = "Contact phone is required")] public string ContactPhone { get; set; } [Required(ErrorMessage = "Latitude is required")] public double Latitude { get; set; } [Required(ErrorMessage = "Longitude is required")] public double Longitude { get; set; } } CODE B: public class DinnerRepository { private NerdDinnerEntities _NerdDinnerEntity = new NerdDinnerEntities(); // Query Method public IQueryable<Dinner> FindAllDinners() { return _NerdDinnerEntity.Dinners; } // Query Method public IQueryable<Dinner> FindUpcomingDinners() { return from dinner in _NerdDinnerEntity.Dinners where dinner.EventDate > DateTime.Now orderby dinner.EventDate select dinner; } // Query Method public Dinner GetDinner(int id) { return _NerdDinnerEntity.Dinners.FirstOrDefault(d => d.DinnerID == id); } // Insert Method public void Add(Dinner dinner) { _NerdDinnerEntity.Dinners.AddObject(dinner); } // Delete Method public void Delete(Dinner dinner) { foreach (var rsvp in dinner.RSVPs) { _NerdDinnerEntity.RSVPs.DeleteObject(rsvp); } _NerdDinnerEntity.Dinners.DeleteObject(dinner); } // Persistence Method public void Save() { _NerdDinnerEntity.SaveChanges(); } } CODE C: // ************************************** // GET: /Dinners/Create/ // ************************************** public ActionResult Create() { Dinner dinner = new Dinner() { EventDate = DateTime.Now.AddDays(7) }; return View(dinner); } // ************************************** // POST: /Dinners/Create/ // ************************************** [HttpPost] public ActionResult Create(Dinner dinner) { if (ModelState.IsValid) { dinner.HostedBy = "The Code Dude"; _dinnerRepository.Add(dinner); _dinnerRepository.Save(); return RedirectToAction("Details", new { id = dinner.DinnerID }); } else { return View(dinner); } } CODE D: // ************************************** // GET: /Dinners/Edit/{id} // ************************************** public ActionResult Edit(int id) { Dinner dinner = _dinnerRepository.GetDinner(id); return View(dinner); } // ************************************** // POST: /Dinners/Edit/{id} // ************************************** [HttpPost] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = _dinnerRepository.GetDinner(id); if (TryUpdateModel(dinner)){ _dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } return View(dinner); } I have sent Wrox and one of the authors a request for help but have not heard back from anyone. Readers of the book cannot even continue to finish the rest of chapter 1 because of these errors. Even if I download the latest build from Codeplex, it still has the same errors. Can someone please help me and tell me what needs to be fixed? Thanks - Ed.

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  • Lucene.NET and searching on multiple fields with specific values...

    - by Kieron
    Hi, I've created an index with various bits of data for each document I've added, each document can differ in it field name. Later on, when I come to search the index I need to query it with exact field/ values - for example: FieldName1 = X AND FieldName2 = Y AND FieldName3 = Z What's the best way of constructing the following using Lucene .NET: What analyser is best to use for this exact match type? Upon retrieving a match, I only need one specific field to be returned (which I add to each document) - should this be the only one stored? Later on I'll need to support keyword searching (so a field can have a list of values and I'll need to do a partial match). The fields and values come from a Dictionary<string, string>. It's not user input, it's constructed from code. Thanks, Kieron

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  • Fields of class, are they stored in the stack or heap?

    - by Mirek
    I saw a question yesterday which raised (for me) another question. Please look at the following code: public class Class1 { int A; //as I uderstand, int is value type and therefore lives in the stack } class Class2 { Run() { Class1 instance1 = new Class1(); instance1.A = 10; //it points to value type, but isnt this reference (on heap)? } } Or while creating the instance of Class1, its field types are created on the heap as well? But then I do not understand when it would really be on the stack as almost always you need to create an instance of object in order to use it fields.

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  • Is there an extensible SQL like query language that is safe for exposing via a public API?

    - by Lokkju
    I want to expose some spatial (and a few non-spatial) datasets via a public API. The backend store will either be PostgreSQL/PostGIS, sqlite/spatialite, or CouchDB/GeoCouch. My goal is to find a some, preferably standard, way to allow people to make complex spatial queries against the data. I would like it to be a simple GET based request. The idea is to allow safe SQL type queries, without allowing unsafe ones. I would rather modify something that is off the shelf than doing the entire thing myself. I specifically want to support requesting specific fields from a table; joining results; and spatial functions that are already implemented by the underlying datastore. Ideas anyone?

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  • Symfony app - how to add calculated fields to Propel objects?

    - by Thomas Kohl
    What is the best way of working with calculated fields of Propel objects? Say I have an object "Customer" that has a corresponding table "customers" and each column corresponds to an attribute of my object. What I would like to do is: add a calculated attribute "Number of completed orders" to my object when using it on View A but not on Views B and C. The calculated attribute is a COUNT() of "Order" objects linked to my "Customer" object via ID. What I can do now is to first select all Customer objects, then iteratively count Orders for all of them, but I'd think doing it in a single query would improve performance. But I cannot properly "hydrate" my Propel object since it does not contain the definition of the calculated field(s). How would you approach it?

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  • How can I set MAXLENGTH on input fields automatically?

    - by Gary McGill
    I'm using ASP.NET MVC RC2. I have a set of classes that were auto-generated "Linq-to-SQL Classes", where each class models a table in my database. I have some default "edit" views that use the neat-o Html.TextBoxFor helper extension to render HTML input fields for the columns in a table. However, I notice that there is no MAXLENGTH attribute specified in the generated HTML. A quick google shows that you can add explicit attributes using TextBoxFor etc. but that would mean that I need to hard-code the values (and I need to remember to do it for every input). This seems pretty poor, considering that everything was automatically generated directly from the DB, so the size of the columns is known. (Although, to be fair, the web-side stuff has to work with any model objects, not just with Linq-to-SQL objects). Is there any nice way of getting this to do the right thing?

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  • How do I sort in solr by term frequency in multiple fields?

    - by user1488380
    I have been assigned a task that I should change our solr search to sort a list returned by solr by using the term frequency. Well, I´ve found a way to do so simply by using omitNorms="true". The problem is, that this won´t work when I am doing a field - search, say by name: q=name:jones Following this example I get a list of document whose term frequency is the highest for the "name" field. But What I wanted to achieve is to have a query that is giving my a list of documents whose term frequency is the highest for ALL fields. Example: If a User named Jones also has the word "Jones" in his biography 10 times I want that document ranked higher. Is that possible ?

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  • problem in displaying list using array adapters

    - by Rahul Varma
    Hi, I am trying to display the list of songs using array adapters. But the problem is i couldnt display the list and only empty screen with preset background is showing up. Here's the code...All the thee are seperate classes... Plz help me... public class SongsAdapter extends ArrayAdapter<SongsList>{ private Context context; TextView tvTitle; TextView tvMovie; TextView tvSinger; String s; public SongsAdapter(Context context, int resource, int textViewResourceId, String title) { super(context, resource, textViewResourceId); this.context=context; } public View getView(int position, View convertView, ViewGroup parent) { final int i=position; List<SongsList> listSongs = new ArrayList<SongsList>(); String title = listSongs.get(i).gettitleName().toString(); String album = listSongs.get(i).getmovieName().toString(); String artist = listSongs.get(i).getsingerName().toString(); String imgal = listSongs.get(i).gettitleName().toString(); LayoutInflater inflater = ((Activity) context).getLayoutInflater(); View v = inflater.inflate(R.layout.row, null); tvTitle=(TextView)v.findViewById(R.id.text2); tvMovie=(TextView)v.findViewById(R.id.text3); tvSinger=(TextView)v.findViewById(R.id.text1); tvTitle.setText(title); tvMovie.setText(album); tvSinger.setText(artist); final ImageView im=(ImageView)v.findViewById(R.id.image); s="http://www.gorinka.com/"+imgal; String imgPath=s; AsyncImageLoaderv asyncImageLoaderv=new AsyncImageLoaderv(); Bitmap cachedImage = asyncImageLoaderv.loadDrawable(imgPath, new AsyncImageLoaderv.ImageCallback() { public void imageLoaded(Bitmap imageDrawable, String imageUrl) { im.setImageBitmap(imageDrawable); } }); im.setImageBitmap(cachedImage); return v; } public class imageloader implements Runnable{ private String ss; private ImageView im; public imageloader(String s, ImageView im) { this.ss=s; this.im=im; Thread thread = new Thread(this); thread.start(); } public void run(){ try { HttpGet httpRequest = null; httpRequest = new HttpGet(ss); HttpClient httpclient = new DefaultHttpClient(); HttpResponse response = (HttpResponse) httpclient.execute(httpRequest); HttpEntity entity = response.getEntity(); BufferedHttpEntity bufHttpEntity = new BufferedHttpEntity(entity); InputStream is = bufHttpEntity.getContent(); Bitmap bm = BitmapFactory.decodeStream(is); Log.d("img","img"); is.close(); im.setImageBitmap(bm); } catch (Exception t) { Log.e("bitmap url", "Exception in updateStatus()", t); } } } } public class SongsList { private String titleName; private String movieName; private String singerName; private String imagePath; private String mediaPath; // Constructor for the SongsList class public SongsList(String titleName, String movieName, String singerName,String imagePath,String mediaPath ) { super(); this.titleName = titleName; this.movieName = movieName; this.singerName = singerName; this.imagePath = imagePath; this.mediaPath = mediaPath; } public String gettitleName() { return titleName; } public void settitleName(String titleName) { this.titleName = titleName; } public String getmovieName() { return movieName; } public void setmovieName(String movieName) { this.movieName = movieName; } public String getsingerName() { return singerName; } public void setsingerName(String singerName) { this.singerName = singerName; } public String getimagePath() { return imagePath; } public void setimagePath(String imagePath) { this.imagePath = imagePath; } public String getmediaPath() { return mediaPath; } public void setmediaPath(String mediaPath) { this.mediaPath = mediaPath; } } public class MusicListActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.openadiuofile); ListView list = (ListView)findViewById(R.id.list1); SongsAdapter adapter = new SongsAdapter(this,R.layout.row, R.id.text2, null); list.setAdapter(adapter); } }

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  • Adding a calculated field to a Query at run time.

    - by JamesB
    I'm getting data using a query in Delphi, and would like to add a calculated field to the query before it runs. The calculated field is using values in code as well as the query so I can't just calculate it in SQL. I know I can attach an OnCalcFields Event to actually make the calculation, but the problem is after adding the calculated field there are no other fields in the query... I did some digging and found that all of the field defs are created but the actual fields are only created if DefaultFields then CreateFields Default Fields is specified procedure TDataSet.DoInternalOpen; begin FDefaultFields := FieldCount = 0; ... end; Which would indicate that if you add fields you only get the fields you added. I would like all the fields in the query AS WELL AS the ones I Add. Is this possible or do I have to add all the fields I'm using as well?

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  • Why will show() only work for fields that are hidden using inline css?

    - by Chris
    I am hiding an element using inline css, like so: <span class="hidden-nojs" style="display:none">Some text</span> Next I use jQuery to show the element, like so: $(".hidden-nojs").show(); This works great. As soon as I remove the inline css and put display:none on the external css stylesheet for the hidden-nojs class, it stops working. This is what I wrote in the external stylesheet: .hidden-nojs { display: none; } I'm assuming that the external stylesheet loads after the jQuery has already run? This is somewhat annoying as I would like to hide multiple elements with css and would like to avoid using inline css. Why will show() only work for fields that are hidden using inline css? How can I fix this problem?

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  • SQL query for getting data in two fields from one column.

    - by AmiT
    I have a table [Tbl1] containing two fields. ID as int And TextValue as nvarchar(max) Suppose there are 7 records. I need a resultset that has two columns Text1 and Text2. The Text1 should have first 4 records and Text2 should have remaining 3 records. [Tbl1] ID | TextValue 1. | Apple 2. | Mango 3. | Orange 4. | Pineapple 5. | Banana 6. | Grapes 7. | Sapota Now, the result-set should have Text1 | Text2 Apple | Banana Mango | Grapes Orange | Sapota Pineapple |

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  • How to limit fields in django-admin depending on user?

    - by minder
    I suppose similar problem would have been discussed here, but I couldn't find it. Let's suppose I have an Editor and a Supervisor. I want the Editor to be able to add new content (eg. a news post) but before publication it has to be acknowledged by Supervisor. When Editor lists all items, I want to set some fields on the models (like an 'ack' field) as read-only (so he could know what had been ack'ed and what's still waiting approval) but the Supervisor should be able to change everything (list_editable would be perfect) What are the possible solutions to this problem?

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  • C#.NET How to access fields in user control dynamically?

    - by Conor H
    Hi, I'm making a settings screen at the moment that will have a radiobutton group which will determine what controls are displayed. The different settings are contained within a UserControl. I am dynamically creating this UserControl like so: panel = new btSettings(); this.Controls.Add(panel); panel.Location = new Point(15, 49); Just wondering how I can access the fields within this control and design time when the object will only be created during run time? Thanks.

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  • Are there any reasons to make all fields and variables final?

    - by Roman
    In my current project I noticed that all class fields and variable inside methods are declared with final modifier whenever it's possible. Just like here: private final XMLStreamWriter _xmlStreamWriter; private final Marshaller _marshaller; private final OutputStream _documentStream; private final OutputStream _stylesStream; private final XMLStreamWriter _stylesStreamWriter; private final StyleMerger _styleMerger; public DocumentWriter(PhysicalPackage physicalPackage) throws IOException { final Package pkg = new Package(physicalPackage); final Part wordDocumentPart = pkg.createPart( "/word/document.xml", "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml", "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"); // styles.xml final Pair<Part, String> wordStylesPart = wordDocumentPart.createRelatedPart(...); ... } Are there any reasons to do so? p.s. As I know project is not supposed to be multithreaded (at least I've heard nothing about it).

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  • how to customize NSTokenField like in "To/ CC" fields in mac mail?

    - by Miraaj
    Hi all, I am able to work with NSTokenField, it is easy to use.. but I want your suggestions on how can I customize it just like it is in "To/ CC" fields in mac mail ie. when no. of tokens in a token field increases height of "To" field gets increased to a certain limit then a vertical scroller starts appearing! By default when we use a token field neither its height gets increased nor a vertical scroller appears! I tried different combinations in IB but I could not obtain mac mail like functionality. Can anyone suggest me some solution for it?? Thanks, Miraaj

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  • How to get all the fields of a row using the SQL MAX function?

    - by Yiannis Mpourkelis
    Consider this table (from http://www.tizag.com/mysqlTutorial/mysqlmax.php): Id name type price 123451 Park's Great Hits Music 19.99 123452 Silly Puddy Toy 3.99 123453 Playstation Toy 89.95 123454 Men's T-Shirt Clothing 32.50 123455 Blouse Clothing 34.97 123456 Electronica 2002 Music 3.99 123457 Country Tunes Music 21.55 123458 Watermelon Food 8.73 This SQL query returns the most expensive item from each type: SELECT type, MAX(price) FROM products GROUP BY type Clothing $34.97 Food $8.73 Music $21.55 Toy $89.95 I also want to get the fields id and name that belong to the above max price, for each row. What SQL query will return a table like this? Id name type price 123455 Blouse Clothing 34.97 123458 Watermelon Food 8.73 123457 Country Tunes Music 21.55 123453 Playstation Toy 89.95

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  • Translate model fields' attributes from a Database with Django?

    - by Luiz C.
    I'm trying to create a Model that has fields that have the following attributes translatable: verbose_name and choices. I can easily do this by tagging the strings and using the i18l middleware. The problem is that I don't want to define the translation in po/mo files. Is there a way to pull this data from a database table? If so, any examples? There are some options out there that offer model content translation. That is not my case. I need to translate the verbose_name, choices and error_messages from database.

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  • Zend Framework: isValid() clears values from disabled form fields!

    - by Andrew
    When you submit a form, disabled form fields are not submitted in the request. So if your form has a disabled form field, it makes working with Zend_Form::isValid() a little frustrating. $form->populate($originalData); $form->my_text_field->disabled = 'disabled'; if (!$form->isValid($_POST)) { //form is not valid //since my_text_field is disabled, it doesn't get submitted in the request //isValid() will clear the disabled field value, so now we have to re-populate the field $form->my_text_field->value($originalData['my_text_field']); $this->view->form = $form; return; } // if the form is valid, and we call $form->getValues() to save the data, our disabled field value has been cleared! Without having to re-populate the form, and create duplicate lines of code, what is the best way to approach this problem?

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  • paintComponent method is not displaying anything on the panel

    - by Captain Gh0st
    I have been trying to debug this for hours. The program is supposed to be a grapher that graphs coordinates, but i cannot get anything to display not even a random line, but if i put a print statement there it works. It is a problem with the paintComponent Method. When I out print statement before g.drawLine then it prints, but it doesn't draw any lines even if i put a random line with coordinates (1,3), (2,4). import java.awt.*; import java.util.*; import javax.swing.*; public abstract class XYGrapher { abstract public Coordinate xyStart(); abstract public double xRange(); abstract public double yRange(); abstract public Coordinate getPoint(int pointNum); public class Paint extends JPanel { public void paintGraph(Graphics g, int xPixel1, int yPixel1, int xPixel2, int yPixel2) { super.paintComponent(g); g.setColor(Color.black); g.drawLine(xPixel1, yPixel1, xPixel2, yPixel2); } public void paintXAxis(Graphics g, int xPixel, int pixelsWide, int pixelsHigh) { super.paintComponent(g); g.setColor(Color.green); g.drawLine(xPixel, 0, xPixel, pixelsHigh); } public void paintYAxis(Graphics g, int yPixel, int pixelsWide, int pixelsHigh) { super.paintComponent(g); g.setColor(Color.green); g.drawLine(0, yPixel, pixelsWide, yPixel); } } public void drawGraph(int xPixelStart, int yPixelStart, int pixelsWide, int pixelsHigh) { JFrame frame = new JFrame(); Paint panel = new Paint(); panel.setPreferredSize(new Dimension(pixelsWide, pixelsHigh)); panel.setMinimumSize(new Dimension(pixelsWide, pixelsHigh)); panel.setMaximumSize(new Dimension(pixelsWide, pixelsHigh)); frame.setLocation(frame.getToolkit().getScreenSize().width / 2 - pixelsWide / 2, frame.getToolkit().getScreenSize().height / 2 - pixelsHigh / 2); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setResizable(false); frame.add(panel); frame.pack(); frame.setVisible(true); double xRange = xRange(); double yRange = yRange(); Coordinate xyStart = xyStart(); int xPixel = xPixelStart - (int) (xyStart.getX() * (pixelsWide / xRange)); int yPixel = yPixelStart + (int) ((xyStart.getY() + yRange) * (pixelsHigh / yRange)); System.out.println(xPixel + " " + yPixel); if(yPixel > 0 && (yPixel < pixelsHigh)) { System.out.println("y"); panel.paintYAxis(panel.getGraphics(), yPixel, pixelsWide, pixelsHigh); } if(xPixel > 0 && (xPixel < pixelsHigh)) { System.out.println("x"); panel.paintXAxis(panel.getGraphics(), xPixel, pixelsWide, pixelsHigh); } for(int i = 0; i>=0; i++) { Coordinate point1 = getPoint(i); Coordinate point2 = getPoint(i+1); if(point2 == null) { break; } else { if(point1.drawFrom() && point2.drawTo()) { int xPixel1 = (int) (xPixelStart + (point1.getX() - xyStart.getX()) * (pixelsWide / xRange)); int yPixel1 = (int) (yPixelStart + (xyStart.getY() + yRange-point1.getY()) * (pixelsHigh / yRange)); int xPixel2 = (int) (xPixelStart + (point2.getX() - xyStart.getX()) * (pixelsWide / xRange)); int yPixel2 = (int) (yPixelStart + (xyStart.getY() + yRange - point2.getY()) * (pixelsHigh / yRange)); panel.paintGraph(panel.getGraphics(), xPixel1, yPixel1, xPixel2, yPixel2); } } } frame.pack(); } } This is how i am testing it is supposed to be a square, but nothing shows up. public class GrapherTester extends XYGrapher { public Coordinate xyStart() { return new Coordinate(-2,2); } public double xRange() { return 4; } public double yRange() { return 4; } public Coordinate getPoint(int pointNum) { switch(pointNum) { case 0: return new Coordinate(-1,-1); case 1: return new Coordinate(1,-1); case 2: return new Coordinate(1,1); case 3: return new Coordinate(-1,1); case 4: return new Coordinate(-1,-1); } return null; } public static void main(String[] args) { new GrapherTester().drawGraph(100, 100, 500, 500); } } Coordinate class so if any of you want to run and try it out. That is all you would need. public class Coordinate { float x; float y; boolean drawTo; boolean drawFrom; Coordinate(double x, double y) { this.x = (float) x; this.y = (float) y; drawFrom = true; drawTo = true; } Coordinate(double x, double y, boolean drawFrom, boolean drawTo) { this.x = (float) x; this.y = (float) y; this.drawFrom = drawFrom; this.drawTo = drawTo; } public double getX() { return x; } public double getY() { return y; } public boolean drawTo() { return drawTo; } public boolean drawFrom() { return drawFrom; } }

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  • What to do with missing fields in sunspot-rails?

    - by chrismealy
    I'm using sunspot/rails version 2. It's working great, but I can't figure out how to handle missing fields. If I don't have latitude and longitude this code will map it to 0,0 (near Africa): searchable do text :resume, :stored => true text :city, :boost => 5 latlon(:geo) { Sunspot::Util::Coordinates.new(latitude, longitude) } end I tried using two search blocks, each with a different conditional, but sunspot just uses the first searchable block. What I want to happen is for things missing locations to still be searchable, just not by location.

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  • A column ID occurred more than once in the specification

    - by Puzzle84
    Recently i've picked up my EF 4.1 / MVC 3 project again and started building in actual frontend capabilities. Now i'm developing a "simple" message system but upon going to that page i get the error as stated in the title EDIT It creates the database just not the models. Stack trace: [NullReferenceException: Object reference not set to an instance of an object.] ASP._Page_Views_Inbox_Index_cshtml.Execute() in c:\Development\MVC\DOCCL\Views\Inbox\Index.cshtml:18 System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197 System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +81 System.Web.WebPages.StartPage.RunPage() +17 System.Web.WebPages.StartPage.ExecutePageHierarchy() +62 System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +76 System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +222 System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115 System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +295 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13 System.Web.Mvc.<c_DisplayClass1c.b_19() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +242 System.Web.Mvc.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b() +21 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList1 filters, ActionResult actionResult) +177 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +324 System.Web.Mvc.Controller.ExecuteCore() +106 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +91 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10 System.Web.Mvc.<c_DisplayClassb.b_5() +34 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +19 System.Web.Mvc.Async.<c_DisplayClass81.<BeginSynchronous>b__7(IAsyncResult _) +10 System.Web.Mvc.Async.WrappedAsyncResult1.End() +62 System.Web.Mvc.<c_DisplayClasse.b_d() +48 System.Web.Mvc.SecurityUtil.b_0(Action f) +7 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9478661 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +178 InnerException : {"A column ID occurred more than once in the specification."} The recently added code is. Controller: // // GET: /Inbox/Index/5/1 public ActionResult Index(int? Id, int Page = 1) { try { const int pageSize = 10; var messages = from m in horseTracker.Messages where m.ReceiverId.Equals(Id) select m; var paginatedMessages = new PaginatedList<Message>(messages, Page, pageSize); return View(paginatedMessages); } catch (Exception ex) { } return View(); } Models public class Message { [Key] public int Id { get; set; } [Required(ErrorMessage = "Subject is required")] [Display(Name = "Subject")] public string Subject { get; set; } [Required(ErrorMessage = "Message is required")] [Display(Name = "Message")] public string Content { get; set; } [Required] [Display(Name = "Date")] public DateTime Created { get; set; } public Boolean Read { get; set; } [Required(ErrorMessage = "Can't create a message without a user")] public int SenderId { get; set; } public virtual User Sender { get; set; } [Required(ErrorMessage = "Please pick a recipient")] public int ReceiverId { get; set; } public virtual User Receiver { get; set; } } public class User { [Key] public int Id { get; set; } [Required] [Display(Name = "Username")] public string UserName { get; set; } [Required] [Display(Name = "First Name")] public string FirstName { get; set; } [Required] [Display(Name = "Last Name")] public string LastName { get; set; } [Required] [Display(Name = "E-Mail")] public string Email { get; set; } [Required] [Display(Name = "Password")] public string Password { get; set; } [Required] [Display(Name = "Country")] public string Country { get; set; } public string EMail { get; set; } //Races public virtual ICollection<Message> Messages { get; set; } } modelBuilder.Entity<User>() .HasMany(u => u.Messages) .WithRequired(m => m.Receiver) .HasForeignKey(m => m.ReceiverId) .WillCascadeOnDelete(false); Anyone have a clue on why i might be getting that error? Before i added these classes it was working fine.

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