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  • sqlalchemy: what is the difference between declaring the cascade within the foreign key vs relation?

    - by steve
    what is the difference between declaring the cascade within a foreign key vs relations? class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id', onupdate="CASCADE", ondelete="CASCADE"))) vs class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact", cascade="all, delete-orphan") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id')) with the foreign key declaration, it seems like the cascade is enforced at the database level. how does the relations approach work? thanks!

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  • mysql eliminate responses under certain condition with join

    - by Dustin
    Forgive me if this is an easy question. I teach classes and want to be able to select those students who have taken one class, but not another class. I have two tables: lessons_slots which is the table for every class such as: -------------------- -ID name slots- -1 basics 10 - -2 advanced 10 - -3 basics 10 - --------------------- The other table is class_roll, which holds enrollment info, such as: -------------------- -sID classid firstname lastname- -1 1 Jo Schmo -2 1 Person Two ... -13 2 Jo Schmo --------------------- What I want to do, I select everyone who has not had the advanced class (for example). I've tried doing SELECT * FROM lessons_slots LEFT JOIN class_roll ON lessons_slots.ID = class_roll.classid WHERE lessons_slots.name != 'advanced' But that doesn't work. Any ideas?

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  • How to pass data to a C++0x lambda function that will run in a different thread?

    - by Dimitri C.
    In our company we've written a library function to call a function asynchronously in a separate thread. It works using a combination of inheritance and template magic. The client code looks as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, &DemoThread::SomeFunction, stringToPassByValue); Since the introduction of lambda functions I'd like to use it in combination with lambda functions. I'd like to write the following client code: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=]() { const std::string someCopy = stringToPassByValue; }); Now, with the Visual C++ 2010 this code doesn't work. What happens is that the stringToPassByValue is not copied. Instead the "capture by value" feature passes the data by reference. The result is that if the function is executed after stringToPassByValue has gone out of scope, the application crashes as its destructor is called already. So I wonder: is it possible to pass data to a lambda function as a copy? Note: One possible solution would be to modify our framework to pass the data in the lambda parameter declaration list, as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=](const std::string stringPassedByValue) { const std::string someCopy = stringPassedByValue; } , stringToPassByValue); However, this solution is so verbose that our original function pointer solution is both shorter and easier to read. Update: The full implementation of AsyncCall is too big to post here. In short, what happens is that the AsyncCall template function instantiates a template class holding the lambda function. This class is derived from a base class that contains a virtual Execute() function, and upon an AsyncCall() call, the function call class is put on a call queue. A different thread then executes the queued calls by calling the virtual Execute() function, which is polymorphically dispatched to the template class which then executes the lambda function.

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  • Iterator blocks and inheritance.

    - by Dave Van den Eynde
    Given a base class with the following interface: public class Base { public virtual IEnumerable<string> GetListOfStuff() { yield return "First"; yield return "Second"; yield return "Third"; } } I want to make a derived class that overrides the method, and adds its own stuff, like so: public class Derived : Base { public override IEnumerable<string> GetListOfStuff() { foreach (string s in base.GetListOfStuff()) { yield return s; } yield return "Fourth"; yield return "Fifth"; } } However, I'm greeted with a warning that "access to a member through a base keyword from an iterator cannot be verified". What's the accepted solution to this problem then?

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  • Help with active record relations

    - by Christian Fazzini
    class CreateActivities < ActiveRecord::Migration def self.up create_table :activities do |t| t.references :user t.references :media t.integer :artist_id t.string :type t.timestamps end end def self.down drop_table :activities end end class Fan < Activity belongs_to :user, :counter_cache => true end class Activity < ActiveRecord::Base belongs_to :user belongs_to :media belongs_to :artist, :class_name => 'User', :foreign_key => 'artist_id' end class User < ActiveRecord::Base has_many :activities has_many :fans end I tried changing my activity model too, without any success: class Activity < ActiveRecord::Base has_many :activities, :class_name => 'User', :foreign_key => 'user_id' has_many :activities, :class_name => 'User', :foreign_key => 'artist_id' end One thing to note. Activity is an STI. Fan inherits from Activity. In console, I do: # Create a fan object. User is a fan of himself fan = Fan.new => #<Fan id: nil, user_id: nil, media_id: nil, artist_id: nil, type: "Fan", comment: nil, created_at: nil, updated_at: nil> # Assign a user object fan.user = User.first => #<User id: 1, genre_id: 1, country_id: 1, .... # Assign an artist object fan.artist_id = User.first.id => 1 # Save the fan object fan.save! => true Activity.last => #<Fan id: 13, user_id: 1, media_id: nil, artist_id: 1, type: "Fan", comment: nil, created_at: "2010-12-30 08:41:25", updated_at: "2010-12-30 08:41:25"> Activity.last.user => #<User id: 1, genre_id: 1, country_id: 1, ..... But... Activity.last.artist => nil Why is Activity.last.artist returning nil?

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  • Makefile to compile both C and Java programs at the same time

    - by user342745
    I have three programs that need to be compiled at the same time, 2 written in C and 1 in java. I had all three working with the Makefile when they were in C, but then switched one of them to java... is there a way to compile all 3 at once with the same makefile? Here is my current Makefile: CC=gcc JC=javac JFLAGS= -g CFLAGS= -Wall -g -std=c99 LDFLAGS= -lm .SUFFIXES: .java .class .java.class: $(JC) $(JFLAGS) $*.java CLASSES = kasiski.java kentry.java ALL= ic ftable kasiski all: $(ALL) ic: ic.o kasiski: $(CLASSES:.java=.class) ftable: ftable.o ic.o: ic.c ic.h ftable.o: ftable.c ftable.h .PHONY: clean clean: rm -rf core* *.class *.o *.gch $(ALL)

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  • Select CSS based on multiple classes

    - by Stacey
    I have a style rule I want to apply to a tag when it has TWO styles. Is there any way to perform this without javascript? In other words.. <li class='left ui-class-selector'> I want to select only if the li has both 'left' and 'ui-class-selector' classes applied.

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  • Zend_Form and Liskov Substitution Principle

    - by blockhead
    A very common pattern I see (I'm picking on Zend Framework, only because I was dealing with it at the moment of this question), is something like this: class My_Form extends Zend_Form { public function init() { $this->addElement(); } } Zend_Form is not an abstract class, but is perfectly usable on its own. This seems to be "recommended" as place to "encapsulate" your forms into a nice class. Does this violate the Liskov Substitution Principle? Each subclass of Zend_Form will have a wildy different behavior than the base class. Would it be better to use composition for this, or am I totally misunderstanding this principle?

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  • Does this code describe an Existential Type in C#?

    - by noblethrasher
    Currently watching Bart De Smet's explanation of IQueryable and he mentioned Existential Types (which I've been curious about for some time). After reading the answers to this question I'm just wondering if this is a way to construct it in C#: public abstract class ExistentialType { private ExistentialType() { } public abstract int Foo(); public ExistentialType Create() { return new ConcreateType1(); } private class ConcreateType1 : ExistentialType { public override int Foo() { throw new NotImplementedException(); } } private class ConcreateType2 : ExistentialType { public override int Foo() { throw new NotImplementedException(); } } private class ConcreateType3 : ExistentialType { public override int Foo() { throw new NotImplementedException(); } } }

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  • C++ IDE for Linux with smart reference searching

    - by Dmitry Yudakov
    Is there an IDE supporting C++ with REALLY smart searching of references? By 'reference' I mean usage of a class (or its member), variable, function in the whole Project or Workspace. There's lots of IDE providing it. Some of them seem just to search for the text with same name giving lots of stuff, others are smarter and check the context (like class boundaries, namespace) but aren't accurate enough. The best I've tried so far was Visual SlickEdit, but still there's more to wish. class C1 { int foo; }; class C2 { int foo; }; For example in this situation when searching for C1::foo references I don't want C2::foo to be shown too. So, is there an IDE that would be so smart?

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  • Regex Problem(C#)

    - by oraclee
    Hi all; Html Code: <TD style="DISPLAY: none">999999999</TD> <TD class=CLS1 >Name</TD> <TD class=BLACA>271229</TD> <TD>220</TD> <TD>343,23</TD> <TD>23,0</TD> <TD>222,00</TD> <TD>33222,8</TD> <TD class=blacl>0</TD> <TD class=black>0</TD> <TD>3433</TD> <TD>40</TD> i need td in value how to make csharp, i wanna string array; 999999999 Name 271229 220 pls help

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  • preload image with jquery

    - by robertdd
    ok, I spent 2 days trying to preloaded images but no succes! i have this function: jQuery.getlastimage = function(id) { $.getjs(); $.post('operations.php', {'operation':'getli', 'id':id,}, function(lastimg){ $("#upimages" + id).html('<a href="uploads/'+ lastimg +'?'+ (new Date()).getTime() +'"><img class="thumbs" id="' + id + '" alt="' + lastimg + '" src="uploads/' + lastimg +'?'+ (new Date()).getTime() + '" /></a>'); }); }; while the image loading i want to appear a gif or a text "Loading...". the function will get something like this: <div class="upimage"> <ul class="thumbs" id="upimagesQueue"> **<li id="#upimagesRIFDIB"> <a href="uploads/0001.jpg?1271800088379"> <img src="uploads/0001.jpg?1271800088379" alt="0001.jpg" id="RIFDIB" class="thumbs"> </a> </li>** <li> .... </li> </ul> </div> i tryed like this: ... $.post('operations.php', {'operation':'getli', 'id':id,}, function(lastimg){ $("#upimages" + id) .html('<a href="uploads/'+ lastimg +'?'+ (new Date()).getTime() +'"><img class="thumbs" id="' + id + '" alt="' + lastimg + '" src="uploads/' + lastimg +'?'+ (new Date()).getTime() + '" /></a>') .hide() .load(function() { $(this).show(); }); ... but all the <li> will hide and after is loading the image appear, i want the <li> to apear with a gif or a text in it and after the image is loaded the link and the image to apear! How to do this? Anyone have an idea? Thanks!

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  • center text in div

    - by Son of anarchy
    <div> <div class="left"> <div align="center" class="node"> <div class="nodeText"> <h2 >test</h2> </div> <div class="node"> <h2>test</h2> </div> <div class="node"> <h2>test</h2> </div> <div> I need to center text in div nothing seems to work .left { float:left; width:200px; border:solid 1px black; text-align: center; } .node { height:200px; border:solid 1px black; margin:0 auto; } .nodeText{ vertical-align: middle; } h2{ text-align: center; } Tnxs

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  • Ads in whole app iPhone problem

    - by lars
    I am using mobclix together with admob. The code is to big to add it in all classes. So i created a new class: Ads Everytime i want an ad in a view, i have to send the view to the ad class: - (void)initAd:(UIView *) pView { NSLog(@"ads init"); self.loadedView = pView; ..... To create an ad in a class: Ad* ad = [Ads new]; [ad initAd:self.view]; I dont know if thats the right way. I have to create a new Ads object everytime i change a view (or class). Is there a way to always have an Ads instance running, or is there another better way? Thanks alot!!

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  • text-transform cannot change/be overwritten? (css)

    - by Radek
    I am studying css and I do not understand why some OTHER text and line 2 has red underline effect on them. I thought I either changed it for class others or reset it to none for class line2 I tried `text-decoration:none' for both .line2 and .others and the text was still red underlined. <html> <head> <style type="text/css"> .line {color:red; text-transform:uppercase; text-decoration:underline;} .line2 {color:blue; text-transform:none;} .others {color:black; text-transform:lowercase; text-decoration:blink; font-weight:bold;} </style> </head> <body> <div class='line'> line 1 <div class='others'><BR>some OTHER text<BR></DIV> <div class='line2'> <BR>line 2 </div> </div> </body> </html>

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  • Remove some tags in jquery

    - by user201140
    I would like to use jquery to remove some tags inside mainclass, so that this - <div class='mainclass'> <div class='inclass'> <a href='#'>Some text</a> </div> </div> Becomes this - <div class='mainclass'> Some text </div> Thanks in advance.

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  • C# -Fluent interface implementation Help

    - by nettguy
    I am implementing the following piece of code using Fluent Interface design in C# 3.0. The code is working fine. public interface ITrainable { ITrainable AddSkill(string _skill); } public interface ISearchSkill { ISearchSkill SearchSkill(SoftwareEngineer emp,string[] _skills); } public abstract class Person { public Person(){} protected string Name { get; set; } } public class SoftwareEngineer:Person,ITrainable { protected internal List<string> skillSet { get; set; } public SoftwareEngineer() { } public SoftwareEngineer(string name) { Name=name; skillSet = new List<string>(); } public ITrainable AddSkill(string _skill) { skillSet.Add(_skill); return this; } } public class HRExecutive :Person,ISearchSkill { SoftwareEngineer _employee; public HRExecutive() { _employee=new SoftwareEngineer(); } public ISearchSkill SearchSkill(SoftwareEngineer _employee,string[] skills) { this._employee= _employee; foreach (string _skill in skills) { if (_employee.skillSet.Contains(_skill)) { Console.WriteLine(Name + " is trained on " + _skill); } else { Console.WriteLine(Name + " is not trained on " + _skill); } } return this; } } Execution SoftwareEngineer emp1 = new SoftwareEngineer("JonSkeet"); emp1.AddSkill("java").AddSkill("C#").AddSkill("F#"); HRExecutive hr = new HRExecutive(); hr.SearchSkill(emp1, new string[] { "java", "C#" }). SearchSkill(emp1, new string[] { "Oracle", "F#" }); Question : I don't want the skillSet of SoftwareEngineer being accessed by some XXX class.It could be accessed by limited classes.But protected internal List<string> skillSet { get; set; } is the only option (i think) i can declare in order to access the skillSet from HRExecutive.If i do so other XXX class can still access it. How to rewrite the code to prevent it?

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  • Instance where embedded C++ compilers don't support multiple inheritance?

    - by Nathan
    I read a bit about a previous attempt to make a C++ standard for embedded platforms where they specifically said multiple inheritance was bad and thus not supported. From what I understand, this was never implemented as a mainstream thing and most embedded C++ compilers support most standard C++ constructs. Are there cases where a compiler on a current embedded platform (i.e. something not more than a few years old) absolutely does not support multiple inheritance? I don't really want to do multiple inheritance in a sense where I have a child with two full implementations of a class. What I am most interested in is inheriting from a single implementation of a class and then also inheriting one or more pure virtual classes as interfaces only. This is roughly equivalent to Java/.Net where I can extend only one class but implement as many interfaces as I need. In C++ this is all done through multiple inheritance rather than being able to specifically define an interface and declare a class implements it.

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  • Add methods to generated WCF client proxy code

    - by dcstraw
    I'd like to add one additional method for each service operation in my WCF client proxy code (i.e. the generated class that derives from ClientBase). I have written a Visual Studio extension that has an IOperationContractGenerationExtension implementation, but this interface only seems to expose the ability to modify the service interface, not the ClientBase-derived class. Is there any way to generate new methods in the proxy client class?

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  • JQuery nth-child not working properly

    - by Keith Donegan
    Hi Guys, I am using JQuery's nth-child selector to alter the margin on every 3rd div with a class of photo_post_thumbnail, but it alters it every 2nd div? Can anyone spot what I am doing wrong? Site http://www.clients.eirestudio.net/hatstand/wordpress/photos/ HTML markup <div class="postbox photo_post_thumbnail"> blah blah </div> <div class="postbox photo_post_thumbnail"> blah blah </div> <div class="postbox photo_post_thumbnail"> blah blah </div> JQuery Code $('.photo_post_thumbnail:nth-child(3n)').css('margin-right', '0px');

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  • Is a many-to-many relationship with extra fields the right tool for my job?

    - by whichhand
    Previously had a go at asking a more specific version of this question, but had trouble articulating what my question was. On reflection that made me doubt if my chosen solution was correct for the problem, so this time I will explain the problem and ask if a) I am on the right track and b) if there is a way around my current brick wall. I am currently building a web interface to enable an existing database to be interrogated by (a small number of) users. Sticking with the analogy from the docs, I have models that look something like this: class Musician(models.Model): first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) dob = models.DateField() class Album(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) class Instrument(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) Where I have one central table (Musician) and several tables of associated data that are related by either ForeignKey or OneToOneFields. Users interact with the database by creating filtering criteria to select a subset of Musicians based on data the data on the main or related tables. Likewise, the users can then select what piece of data is used to rank results that are presented to them. The results are then viewed initially as a 2 dimensional table with a single row per Musician with selected data fields (or aggregates) in each column. To give you some idea of scale, the database has ~5,000 Musicians with around 20 fields of related data. Up to here is fine and I have a working implementation. However, it is important that I have the ability for a given user to upload there own annotation data sets (more than one) and then filter and order on these in the same way they can with the existing data. The way I had tried to do this was to add the models: class UserDataSets(models.Model): user = models.ForeignKey(User) name = models.CharField(max_length=100) description = models.CharField(max_length=64) results = models.ManyToManyField(Musician, through='UserData') class UserData(models.Model): artist = models.ForeignKey(Musician) dataset = models.ForeignKey(UserDataSets) score = models.IntegerField() class Meta: unique_together = (("artist", "dataset"),) I have a simple upload mechanism enabling users to upload a data set file that consists of 1 to 1 relationship between a Musician and their "score". Within a given user dataset each artist will be unique, but different datasets are independent from each other and will often contain entries for the same musician. This worked fine for displaying the data, starting from a given artist I can do something like this: artist = Musician.objects.get(pk=1) dataset = UserDataSets.objects.get(pk=5) print artist.userdata_set.get(dataset=dataset.pk) However, this approach fell over when I came to implement the filtering and ordering of query set of musicians based on the data contained in a single user data set. For example, I could easily order the query set based on all of the data in the UserData table like this: artists = Musician.objects.all().order_by(userdata__score) But that does not help me order by the results of a given single user dataset. Likewise I need to be able to filter the query set based on the "scores" from different user data sets (eg find all musicians with a score 5 in dataset1 and < 2 in dataset2). Is there a way of doing this, or am I going about the whole thing wrong?

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  • How to implement "select sum()" in Grails

    - by xain
    I have a relationship like this: class E { string name hasMany = [me:ME] } class M { float price } class ME { E e M m int quantity } And I'd hate to iterate to achieve this: "obtain the sum of the quantity in ME times the price of the corresponding M for a given E". Any hints on how to implement it using GORM/HQL ? Thanks in advance

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  • What are the requirments for ISupportInitialize code to be serialized in InitializeComponent? .Net

    - by Jules
    I need to add some code to the EndInit method of a PictureBox control but unfortunately its private and, from what I can gather, I can't shadow it and call base - at least not in VB.Net. What I can do is add a dummy property to my picture box class. The type of the dummy property is simply a class that just implements ISupportInitialize. However, that doesn't work, I need the dummy class to inherit from Control. Is that the minimum requirement?

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  • NHibernate: How is identity Id updated when saving a transient instance?

    - by bretddog
    If I use session-per-transaction and call: session.SaveOrUpdate(entity) corrected: session.SaveOrUpdateCopy(entity) ..and entity is a transient instance with identity-Id=0. Shall the above line automatically update the Id of the entity, and make the instance persistent? Or should it do so on transaction.Commit? Or do I have to somehow code that explicitly? Obviously the Id of the database row (new, since transient) is autogenerated and saved as some number, but I'm talking about the actual parameter instance here. Which is the business logic instance. EDIT Mappings: public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name); HasMany(x => x.Staff) // 1:m .Cascade.All(); HasManyToMany(x => x.Products) // m:m .Cascade.All() .Table("StoreProduct"); } } public class EmployeeMap : ClassMap<Employee> { public EmployeeMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.FirstName); Map(x => x.LastName); References(x => x.Store); // m:1 } } public class ProductMap : ClassMap<Product> { public ProductMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name).Length(20); Map(x => x.Price).CustomSqlType("decimal").Precision(9).Scale(2); HasManyToMany(x => x.StoresStockedIn) .Cascade.All() .Inverse() .Table("StoreProduct"); } } EDIT2 Class definitions: public class Store { public int Id { get; private set; } public string Name { get; set; } public IList<Product> Products { get; set; } public IList<Employee> Staff { get; set; } public Store() { Products = new List<Product>(); Staff = new List<Employee>(); } // AddProduct & AddEmployee is required. "NH needs you to set both sides before // it will save correctly" public void AddProduct(Product product) { product.StoresStockedIn.Add(this); Products.Add(product); } public void AddEmployee(Employee employee) { employee.Store = this; Staff.Add(employee); } } public class Employee { public int Id { get; private set; } public string FirstName { get; set; } public string LastName { get; set; } public Store Store { get; set; } } public class Product { public int Id { get; private set; } public string Name { get; set; } public decimal Price { get; set; } public IList<Store> StoresStockedIn { get; private set; } }

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