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  • Conditional insert as a single database transaction in HSQLDB 1.8?

    - by Kevin Pauli
    I'm using a particular database table like a "Set" data structure, i.e., you can attempt to insert the same row several times, but it will only contain one instance. The primary key is a natural key. For example, I want the following series of operations to work fine, and result in only one row for Oklahoma: insert into states_visited (state_name) values ('Oklahoma'); insert into states_visited (state_name) values ('Texas'); insert into states_visited (state_name) values ('Oklahoma'); I am of course getting an error due to the duplicate primary key on subsequent inserts of the same value. Is there a way to make the insert conditional, so that these errors are not thrown? I.e. only do the the insert if the natural key does not already exist? I know I could do a where clause and a subquery to test for the row's existence first, but it seems that would be expensive. That's 2 physical operations for one logical "conditional insert" operation. Anything like this in SQL? FYI I am using HSQLDB 1.8

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  • Is it possible for two VS2008 C# class library projects to share a single namespace?

    - by jeah
    I am trying to share a common namespace between two projects in a single solution. The projects are "Blueprint" and "Repositories". Blueprint contains Interfaces for the entire application and serves as a reference for the application structure. In the Blueprint project, I have an interface with the following declaration: namespace Application.Repositories{ public interface IRepository{ IEntity Get(Guid id); } } In the Repositories project I have a class the following class: namespace Application.Repositories{ public class STDRepository: IRepository { STD Get(Guid id){ return new SkankyExGirlfriendDataContext() .FirstOrDefault<STD>(x=>x.DiseaseId == id); } } } However, this does not work. The Repositories project has a reference to the Blueprint project. I receive a VS error: "The type or namespace name 'IRepository' could not be found (are you missing a using directive or an assembly reference?) - Normally, this is easy to fix but adding a using statement doesn't make sense since they have the same namespace. I tried it anyway and it didn't work. The reference has been added, and without the line of code referencing that interface, both projects compile successfully. I am lost here. I have searched all over and have found nothing, so I am assuming that there is something fundamentally wrong with what I'm doing ... but I don't know what it is. So, I would appreciate some explanation or guidance as to how to fix this problem. I hope you guys can help. Note: The reason I want to do it this way and keep the interfaces under the same namespace is because I want a solid project to keep all the interfaces in, in order to have a reference for the full architecture of the application. I have considered work arounds, such as putting all of the interfaces in the Blueprint.Application namespace instead of the application namespace. However, that would require me to write the using statement on virtually every page in the application...and my fingers get tired. Thanks again guys...

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  • What is the most effective way to create BigInteger instance from int value?

    - by Roman
    I have a method (in 3rd-party library) with BigInteger parameter: public void setValue (BigInteger value) { ... } I don't need 'all its power', I only need to work with integers. So, how can I pass integers to this method? My solution is to get string value from int value and then create BigInteger from string: int i = 123; setValue (new BigInteger ("" + i)); Are there any other (recommended) ways to do that?

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  • In what circumstances are instance variables declared as '_var' in 'use fields' private?

    - by Pedro Silva
    I'm trying to understand the behavior of the fields pragma, which I find poorly documented, regarding fields prefixed with underscores. This is what the documentation has to say about it: Field names that start with an underscore character are made private to the class and are not visible to subclasses. Inherited fields can be overridden but will generate a warning if used together with the -w switch. This is not consistent with its actual behavior, according to my test, below. Not only are _-prefixed fields visible within a subclass, they are visible within foreign classes as well (unless I don't get what 'visible' means). Also, directly accessing the restricted hash works fine. Where can I find more about the behavior of the fields pragma, short of going at the source code? { package Foo; use strict; use warnings; use fields qw/a _b __c/; sub new { my ( $class ) = @_; my Foo $self = fields::new($class); $self->a = 1; $self->b = 2; $self->c = 3; return $self; } sub a : lvalue { shift->{a} } sub b : lvalue { shift->{_b} } sub c : lvalue { shift->{__c} } } { package Bar; use base 'Foo'; use strict; use warnings; use Data::Dumper; my $o = Bar->new; print Dumper $o; ##$VAR1 = bless({'_b' => 2, '__c' => 3, 'a' => 1}, 'Foo'); $o->a = 4; $o->b = 5; $o->c = 6; print Dumper $o; ##$VAR1 = bless({'_b' => 5, '__c' => 6, 'a' => 4}, 'Foo'); $o->{a} = 7; $o->{_b} = 8; $o->{__c} = 9; print Dumper $o; ##$VAR1 = bless({'_b' => 8, '__c' => 9, 'a' => 7}, 'Foo'); }

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  • In what circumstances are instance variables declared as '_var' in 'use fields' readonly?

    - by Pedro Silva
    I'm trying to understand the behavior of the fields pragma, which I find poorly documented, regarding fields prefixed with underscores. This is what the documentation has to say about it: Field names that start with an underscore character are made private to the class and are not visible to subclasses. Inherited fields can be overridden but will generate a warning if used together with the -w switch. This is not consistent with its actual behavior, according to my test, below. Not only are _-prefixed fields visible within a subclass, they are visible within foreign classes as well (unless I don't get what 'visible' means). Also, directly accessing the restricted hash works fine. Where can I find more about the behavior of the fields pragma, short of going at the source code? { package Foo; use strict; use warnings; use fields qw/a _b __c/; sub new { my ( $class ) = @_; my Foo $self = fields::new($class); $self->a = 1; $self->b = 2; $self->c = 3; return $self; } sub a : lvalue { shift->{a} } sub b : lvalue { shift->{_b} } sub c : lvalue { shift->{__c} } } { package Bar; use base 'Foo'; use strict; use warnings; use Data::Dumper; my $o = Bar->new; print Dumper $o; ##$VAR1 = bless({'_b' => 2, '__c' => 3, 'a' => 1}, 'Foo'); $o->a = 4; $o->b = 5; $o->c = 6; print Dumper $o; ##$VAR1 = bless({'_b' => 5, '__c' => 6, 'a' => 4}, 'Foo'); $o->{a} = 7; $o->{_b} = 8; $o->{__c} = 9; print Dumper $o; ##$VAR1 = bless({'_b' => 8, '__c' => 9, 'a' => 7}, 'Foo'); }

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  • Object reference not set to an instance of an object - how to find the offending object name in the

    - by Jason
    This is the bane of my programming existence. After deploying an application, when this error crops up, no amount of debug dump tells you WHAT object was not instantiated. I have the call stack, that's great, it tells me roughly where the object is, but is there any way to get .NET to tell me the actual name of the object? If you catch them while debugging, of course the program breaks right on the offending creature, but if it happens after the program is in the wild, good luck. There has to be a way. I've explored the exceptions returned in these instances and there is just nothing helpful.

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  • How create single HTML file to viewed in Excel with multiple sheets?

    - by Dmitry Nelepov
    I want know, is it possible create single HTML file wich (after chaging extension to xls) when opened at Excel will parsed to multiple sheets. Little example i got file test.xls with contents <html> <body> <table> <tr> <td> 1 </td> <td> 2 </td> <td> 3 </td> <td> =sum(A1:C1) </td> </tr> </table> </body> </html> When i open this file at Excel i got one Sheet with calculated sum of cells A1 to C1 in A4=6 I wonder, it's possible create a HTML file wich containts multiple tables wich will be parsed as multiple sheets at Excel. Here Excel view of this file

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  • How can I retrieve the instance of an attribute's associated object?

    - by Brandon Linton
    I'm writing a PropertiesMustMatch validation attribute that can take a string property name as a parameter. I'd like it to find the corresponding property by name on that object and do a basic equality comparison. What's the best way to access this through reflection? Also, I checked out the Validation application block in the Enterprise Library and decided its PropertyComparisonValidator was way too intense for what we need.

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  • Visual Studio 2008\Backup Files folder created when every new VS instance is opened.

    - by Lukasz Podolak
    Hi, I think I have something broken with the path that VS 2008 saves the backup files. Since few days, it creates a new "Visual Studio 2008" directory in the same folder that my .sln file exists. Then, after the time of the first auto-save expires, the backup files are being saved to this folder. I browsed the tools-options dialog but I haven't found a way to set the directory to by static: C:\documents and setings\\My Documents\Visual Studio 2008\Backup Files. Can anybody point me with the right solution to this problem (probably the correct registry entry - I guess) ? thanks

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  • How to get to the key name of a referenced entity property from an entity instance without a datastore read in google app engine?

    - by Sumeet Pareek
    Consider I have the following models - class Team(db.Model): # say I have just 5 teams name = db.StringProperty() class Player(db.Model): # say I have thousands of players name = db.StringProperty() team = db.ReferenceProperty(Team, collection_name="player_set") Key name for each Team entity = 'team_' , and for each Player entity = 'player_' By some prior arrangement I have a Team entity's (key_name, name) mapping available to me. For example (team_01, United States Of America), (team_02, Russia) etc I have to show all the players and their teams on a page. One way of doing this would be - players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(player.team.name) #This is a total of 1x1000 = 1000 DB reads That is a 1001 DB reads for a silly thing. The interesting part is that when I do a db.to_dict() on players, it shows that for every player in that list there is 'name' of the player and there is the 'key_name' of the team available too. So how can I do the below ?? players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(team_list[player.<SOME WAY OF GETTING TEAM KEY NAME>]) # Here 'team_list' already has (key_name, name) for all 5 teams I have been struggling with this for a long time. Have read every available documentation. I could just hug the person that can help me here :-) Disclaimer: The above problem description is not a real scenario. It is a simplified arrangement that represents my problem exactly. I have run into it in a rater complex and big GAE appication.

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  • Why can't I access the instance.__class__ attribute in Python?

    - by froadie
    I'm new to Python, and I know I must be missing something pretty simple, but why doesn't this very, very simple code work? class myClass: pass testObject = myClass print testObject.__class__ I get the following error: AttributeError: class myClass has no attribute '__class__' Doesn't every object in Python have a __class__ attribute?

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  • ASP.Net MVC 2 is it possible to get the same instance of model(with slight changes) in HttpPost meth

    - by jjjjj
    Hi I have a complex entity User: public class User : BaseEntity { public virtual Taxi Taxi { get; set; } --> That is why i call it "complex" public virtual string Login { get; set; } public virtual string Password { get; set; } } where Taxi is a parent of User (Taxi has-many Users): public class Taxi : BaseEntity { public virtual string Name { get; set; } public virtual string ClientIp { get; set; } } BaseEntity consists of public virtual int Id { get; private set; } The problem occurs while trying to edit User [Authorize] public ActionResult ChangeAccountInfo() { var user = UserRepository.GetUser(User.Identity.Name); return View(user); } My ChangeAccountInfo.aspx <fieldset> <legend>Fields</legend> <% %> <div class="editor-label"> <%: Html.LabelFor(model => model.Login) %> </div> <div class="editor-field"> <%: Html.TextBoxFor(model => model.Login) %> <%: Html.ValidationMessageFor(model => model.Login) %> </div> <div class="editor-label"> <%: Html.LabelFor(model => model.Password) %> </div> <div class="editor-field"> <%: Html.TextBoxFor(model => model.Password) %> <%: Html.ValidationMessageFor(model => model.Password) %> </div> <div class="editor-field"> <%: Html.HiddenFor(model => model.Taxi.Name)%> </div> <p> <input type="submit" value="Save" /> </p> </fieldset> Post changes: [Authorize] [HttpPost] public ActionResult ChangeAccountInfo(User model) { if (ModelState.IsValid) { UserRepository.UpdateUser(model); return RedirectToAction("ChangeAccountInfoSuccess", "Account"); } return View(model); } But, the (User model) parameter has User.Id == 0 -- User entity had 5 before edit User.Login == "my new login" User.Password == "my new password" User.Taxi.Id == 0 -- User.Taxi entity had 3 before edit User.Taxi.Name == "old hidden name" User.Taxi.ClientIp == null -- User entity had 192.168.0.1 before edit Q: Is it possible not to mark all the fields of an entity (that should be in my UpdateUser) with tag "hidden" but still have them unchanged in my HttpPost method? e.g. not User.Taxi.ClientIp = null, but User.Taxi.ClientIp = 192.168.0.1 I'm using nhibernate, if it matters.

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  • How do I check if an instance has an object to skip displaying the values?

    - by Angela
    I have created a polymorphic association around a model called status. Some contacts will have a status associated with it. Many won't. If I try to call a status when one is not there, I get an error. Right now, even if I haven't created a status for the model, it still runs whatever is in the if-end block. Here's what I am trying, but it's not working: <% if [email protected]? %> <p>Status: <%= @status.find(:last).status %></p> <% end %> In the controller, it is defined below: @status = Contact.find(@contact).statuses By the way, also open to make code more readable and DRY.

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  • Object reference not set to an instance of an object.....?

    - by jamal
    Hi guys I always got this error from my site and it keeps bugging me.I've been trying to figure out the cause of this error but I can't really figure it out. Here's the stacktrace: at BasePage.Page_PreInit(Object sender, EventArgs e) at System.EventHandler.Invoke(Object sender, EventArgs e) at System.Web.UI.Page.OnPreInit(EventArgs e) at System.Web.UI.Page.PerformPreInit() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) And on my basepage I only got this code: Imports Microsoft.VisualBasic Public Class BasePage Inherits System.Web.UI.Page Private Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit Page.Theme = "Something" If (Request.UserAgent.IndexOf("AppleWebKit") 0) Then Request.Browser.Adapters.Clear() End If End Sub Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender If Me.Title = "Untitled Page" Then Throw New Exception("Page title cannot be ""Untitled Page"".") End If End Sub End Class According to the stacktrace this always happens on my basepage preinit event.What do you think is the problem here guys?

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  • Python list should be empty on class instance initialisation, but it's not. Why?

    - by canavanin
    Hi everyone! I would like to create instances of a class containing a list that's empty by default; instead of later setting this list to the final full list I would like to successively add items to it. Here's a piece of sample code illustrating this: #!/usr/bin/python class test: def __init__(self, lst=[], intg=0): self.lista = lst self.integer = intg name_dict = {} counter = 0 for name in ('Anne', 'Leo', 'Suzy'): counter += 1 name_dict[name] = test() name_dict[name].integer += 1 name_dict[name].lista.append(counter) print name, name_dict[name].integer, name_dict[name].lista When I ran the above program I expected to get Anne 1 [1] Leo 1 [2] Suzy 1 [3] as I assumed lista to always be initialised to an empty list. What I got instead was this: Anne 1 [1] Leo 1 [1, 2] Suzy 1 [1, 2, 3] If I replace self.lista = lst by self.lista = [] it works fine, just like when I add the line name_dict[name].lista = [] to the for loop. Why is it that the contents of the previous objects' lists are retained, yet their values of integer aren't? I am rather new to Python, so it would be great if someone could point out to me where my thoughts/assumptions have gone astray. Thanks a lot in advance for your replies.

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  • Bash: Continue script if only one instance is running.

    - by Andrew
    Hello, now this is embarrassing. I'm writing quick script and I can't figure out why this statement don't work. if [ $(pidof -x test.sh | wc -w) -eq 1 ]; then echo Passed; fi I also tried using back-ticks instead of $() but it still wouldn't work. Can you see what is wrong with it? pidof -x test.sh | wc -w returns 1 if I run it inside of script, so I don't see any reason why basically if [ 1 -eq 1 ] wouldn't pass. Thanks a lot!

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  • Explicitly typing variables causes compiler to think an instance of a builtin type doesn't have a pr

    - by wallacoloo
    I narrowed the causes of an AS3 compiler error 1119 down to code that looks similar to this: var test_inst:Number = 2.953; trace(test_inst); trace(test_inst.constructor); I get the error "1119: Access of possibly undefined property constructor through a reference with static type Number." Now if I omit the variable's type, I don't get that error: var test_inst = 2.953; trace(test_inst); trace(test_inst.constructor); it produces the expected output: 2.953 [class Number] So what's the deal? I like explicitly typing variables, so is there any way to solve this error other than not providing the variable's type?

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  • Passing parameter to base class constructor or using instance variable?

    - by deamon
    All classes derived from a certain base class have to define an attribute called "path". In the sense of duck typing I could rely upon definition in the subclasses: class Base: pass # no "path" variable here def Sub(Base): def __init__(self): self.path = "something/" Another possiblity would be to use the base class constructor: class Base: def __init__(self, path): self.path = path def Sub(Base): def __init__(self): super().__init__("something/") What would you prefer and why? Is there a better way?

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  • in c# ,one array of class and two connected instance of it why ?

    - by Al0NE
    Hi I wrote the code below : 1. MyClass[] origArr=new MyClass[3]; 2. MyClass[] arr1; 3. // filled the array with objects and did some work on it . 4. dgv_1.DataSource=origArr; 5. 6. // Here is the problem : 7. arr1=origArr; 8. // do some work on arr1 ... 9. dgv_2.DataSource=arr1; For some reason the data in 'origArr' changed when data in 'arr1' change ... I thought that maybe this happened because 'origArr' and 'arr1' are pointers referring to the same object so I changed line '7' to : 7. origArr.CopyTo(arr1,0); but it didn't work ... what can i do to make the pointers referring to different objects?

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  • Why doesn't the .click() not work in this instance?

    - by Deshiknaves
    Basically what this does is fadeIn pre-existing divs and then loads an image. When the image is loaded it then appends that into one of the pre-existing divs. Then it appends a new div with an id of xButton. Then later it $('#xButton').click() should hide the 3 divs. However it just doesn't work. If I change the click() to either #modalImage or #overlay, it works but just not for the #xButton. I would really like to figure out why its not working and how I should be doing this instead. Thanks. $(function(){ $('#container a').click(function(e){ e.preventDefault(); var id = $(this).attr('href'), img = new Image(); $('#overlay').fadeIn(function(){ $('#modalImage').fadeIn(); }); $(img).load(function(){ $(this).hide(); $('#modalImage').removeClass('loader').append(this); $(this).fadeIn(function(){ var ih = $(this).outerHeight(), iw = $(this).outerWidth(), newH = ($(window).height()/10)*7, newW = ($(window).width()/10)*7; if (ih >= iw && ih >= newH) { $(this).css('height',newH + 'px'); $(this).css('width', 'auto'); } else if (ih >= iw && newH > ih) { $(this).css('height', ih + 'px'); $(this).css('width', 'auto'); } else if (iw > ih && iw >= newW) { if ((newW / (iw / ih)) > newH) { $(this).css('width', 'auto'); $(this).css('height', newH + 'px'); } else { $(this).css('width', newW + 'px'); $(this).css('height', 'auto'); } } else { $(this).css('width', iw + 'px'); $(this).css('height', 'auto'); } var padW = ($(window).width() - $(this).outerWidth()) / 2, padH = ($(window).height() - $(this).outerHeight()) / 2; console.log (padH + ' ' + padW); $(this).css('top', padH); $(this).css('left', padW); if($('#overlay').is(":visible") == true) { ih = ih + 4; $('<div id="xButton">x</div>').appendTo('#modalImage'); if (padH >= 0) { $('#xButton').css('top', padH - 4).css('right', padW - 65); } else { $('#xButton').css('top', '20px').css('right', padW - 65); } } }); }).attr('src', id); }); $('#xButton').click(function(){ $(this).hide(); $('#overlay').fadeOut(function(){ $('#modalImage img').css('top', '-9999px').remove(); $('#xButton').remove(); $('#modalImage').addClass('loader'); }); }); });

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