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  • GH-Unit for unit testing Objective-C code, why am I getting linking errors?

    - by djhworld
    Hi there, I'm trying to dive into the quite frankly terrible world of unit testing using Xcode (such a convoluted process it seems.) Basically I have this test class, attempting to test my Show.h class #import <GHUnit/GHUnit.h> #import "Show.h" @interface ShowTest : GHTestCase { } @end @implementation ShowTest - (void)testShowCreate { Show *s = [[Show alloc] init]; GHAssertNotNil(s,@"Was nil."); } @end However when I try to build and run my tests it moans with this error: - Undefined symbols: "_OBJC_CLASS_$_Show", referenced from: __objc_classrefs__DATA@0 in ShowTest.o ld: symbol(s) not found collect2: ld returned 1 exit status Now I'm presuming this is a linking error. I tried following every step in the instructions located here: - http://github.com/gabriel/gh-unit/blob/master/README.md And step 2 of these instructions confused me: - In the Target 'Tests' Info window, General tab: Add a linked library, under Mac OS X 10.5 SDK section, select GHUnit.framework Add a linked library, select your project. Add a direct dependency, and select your project. (This will cause your application or framework to build before the test target.) How am I supposed to add my project to the linked library list when all it accepts it .dylib, .framework and .o files. I'm confused! Thanks for any help that is received.

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  • Lost Update Anomaly in Sql Server Update Command

    - by Javed
    Hi, I am very much confused. I have a transaction in ReadCommitted Isolation level. Among other things I am also updating a counter value in it, something similar to below: Update tblCount set counter = counter + 1 My application is a desktop application and this transaction happens to occur quite frequently and concurrently. We recently noticed an error that sometimes the counter value doesn't get updated or is missed. We also insert one record on each counter update so we are sure that records have been inserted but somehow counter fails to update. This happens once in 2000 simulaneous transactions. I seriously doubt it is a lost update anomaly I am facing but if you look at the command above, it's just update the counter from its own value: if I have started a transaction and the transaction has reached this statement, it should have locked the row. This should not cause lost update, but it's happening somehow. Is the thing that this update command works in two parts? Like first it reads the counter value (during which it doesn't get the exclusive lock) and then writes the new calculated value (when it does get an exclusive lock)? Please help, I have got really confused.

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  • Using HttpClient with SSL and certificates

    - by ChrisCM
    While I've been familiar with HTTPS and the concept of SSL, I have recently begun some development and found I am a little confused. The requirement was that I write a small Java application that runs on a machine attached to a scanner. When a document is scanned this is picked up and the file (usually PDF) sent over the internet to our application server that will then process it. I've written the application using Apache Commons libraries and HTTPClient. The second requirement was to connect over SSL, requiring a certificate. Following guidance on the HTTPclient page I am using AuthSSLProtocolSocketFactory from the contributions page. The constructor can take a keystore, keystore password, truststore and truststore password. As an initial test our DBA enabled SSL on one of our development webservers and provided me with a .p12 file which when I imported into IE allows me to connect successfully. I am a bit confused between keystores and truststores and what steps I need to take using the keytool. I tried importing the p12 into a keystore file but get the error: keytool error: java.lang.Exception: Input not an X.509 certificate I followed a suggestion of importing the p12 into Internet Explorer and exporting as a .cer which I can then successfully import into a keystore. When I supply this as a keystore argument of the AuthSSLProtocolSocketFactory I get a meaningless errror, but if I try it as a truststore it seems like it reads it fine but ultimately I get Caused by: javax.net.ssl.SSLHandshakeException: Received fatal alert: bad_certificate I am unsure if I have missed some steps, I am misunderstanding SSL and mutual authentication altogether or this is mis-configuration on the server side. Can anyone provide suggestions or point me towards resources that might help me figure this out please?

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  • Google Federated Login vs Hybrid Protocol vs Google Data Authentication. Whats's the Difference?

    - by johnfelix
    Hi, I am trying to implement Google Authentication in my website, in which I would also be pulling some Google Data using the Google Data API and I am using Google App Engine with Jinja2. My question is, so many ways are mentioned to do it. I am confused between Google Federated Login,Google Data Protocol, Hybrid Protocol. Are these things the same or different ways to do the same thing. From what I read and understood, which might be incorrect, Google Federated Login uses the hybrid protocol to authenticate and fetch the google data. Is there a proper guide to implement any one of these in python. Examples which I found at the google link are kind of different. From what I understood,correct me if i am wrong, I have to implement only the OpenID Consumer part. In order to implement Google Federated Login in Python, I saw that we need to download a separate library from the openid-enabled.com but I found a different library for the google data implementation at http://code.google.com/p/gdata-python-client/ As you can see, I am confused a lot :D. Please help me :) Thanks

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  • Break on EXC_BAD_ACCESS in XCode?

    - by jasonh
    I'm new to iPhone development and XCode in general and have no idea how to begin troubleshooting an EXC_BAD_ACCESS signal. How can I get XCode to break at the exact line that is causing the error? I can't seem to get XCode to stop on the line causing the problem, but I do see the following lines in my debug console: Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextSetStrokeColorWithColor: invalid context Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextSetLineWidth: invalid context Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextAddPath: invalid context Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextDrawPath: invalid context 2009-10-25 15:12:14.680 LanderTest[1289:207] *** -[CFArray objectAtIndex:]: message sent to deallocated instance 0x3c4e610 Now, I am attempting to draw to the context I retrieve from UIGraphicsGetCurrentContext() and pass to the object that I want to draw with. Further trial and error debugging and I found that an NSMutableArray I have a property for on my class was a zombie. I went into the init function for the class and here's the code I was using: if ((self = [super init])) { NSMutableArray *array = [NSMutableArray array]; self.terrainBlocks = array; [array release]; } return self; } I removed the [array release] line and it no longer gives me the EXC_BAD_ACCESS signal, but I'm now confused about why this works. I thought that when I used the property, it automatically retained it for me, and thus I should release it from within init so that I don't have a leak. I'm thoroughly confused about how this works and all the guides and Stackoverflow questions I've read only confuse me more about how to set properties within my init method. There seems to be no consensus as to which way is the best.

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  • Help to understand the issue with protected method

    - by zeroed
    I'm reading Sybex Complete Java 2 Certification Study Guide April 2005 (ISBN0782144195). This book is for java developers who wants to pass java certification. After a chapter about access modifiers (along with other modifiers) I found the following question (#17): True or false: If class Y extends class X, the two classes are in different packages, and class X has a protected method called abby(), then any instance of Y may call the abby() method of any other instance of Y. This question confused me a little. As far as I know you can call protected method on any variable of the same class (or subclasses). You cannot call it on variables, that higher in the hierarchy than you (e.g. interfaces that you implement). For example, you cannot clone any object just because you inherit it. But the questions says nothing about variable type, only about instance type. I was confused a little and answered "true". The answer in the book is False. An object that inherits a protected method from a superclass in a different package may call that method on itself but not on other instances of the same class. There is nothing here about variable type, only about instance type. This is very strange, I do not understand it. Can anybody explain what is going on here?

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  • Handling events from user control containing a WPF textbox

    - by Tom
    I've been successful in putting a WPF textbox into an existing windows form using ElementHost and a user control. It looks like the following: Public Class MyUserControl Private _elementHost as ElementHost = New ElementHost Private _wpfTextbox as System.Windows.Controls.Textbox = New System.Windows.Controls.Textbox Public Sub New() Me.Controls.Add(_elementHost) _elementHost.Dock = DockStyle.Fill _elementHost.Child = _wpfTextbox _wpfTextbox.SpellCheck.IsEnabled = True End Sub End Class Now, when I put this user control onto a windows form, it accepts keyboard input and the form itself can get text from the textbox. However, when I try to handle keypress (or keydown, keyup) events from the user control, nothing happens. I've looked into this problem and did a bit of research but now I'm a little confused as to what I really need to be looking at. The following are the topics that I am somewhat confused about. HwndSource Relaxed delegates WPF routed events If I am interpreting everything correctly, input from WPF textboxes are handled differently compared to regular form textboxes. It seems like both aren't compatible with each other but there must be some way to "pass" keys from one to another? I'd appreciate any help.

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  • How to get raw jpeg data (but no metatags / proprietary markers)

    - by CoolAJ86
    I want to get raw jpeg data - no metadata. I'm very confused looking at the jpeg "standards". How correct is my understanding of the marker "tree"? 0xFFD8 - Identifies the file as an image 0xFFE? - EXIF, JFIF, SPIFF, ICC, etc 0x???? - the length of the tag 0xFFD8 - Start of Image 0xFFE0 - should follow SOI as per spec, but often preceded by comments ??? 0x???? - Matrices, tags, random data ??? There are never other markers in-between these markers? Or these include the matrices and such? 0xFFDA - Start of Stream - This is what I want, yes? 0xXXXX - length of stream 0xFFD9 - End of Stream (EOI) 0x???? - Comment tags, extra exif, jfif info??? 0xFFD9 - End of Image 0xFF00 - escaped 0xFF, not to be confused with a marker This has been my reading material: http://en.wikipedia.org/wiki/JPEG http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html http://www.media.mit.edu/pia/Research/deepview/exif.html http://www.faqs.org/faqs/jpeg-faq/part1/section-15.html

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  • Need some help understanding this problem about maximizing graph connectivity

    - by Legend
    I was wondering if someone could help me understand this problem. I prepared a small diagram because it is much easier to explain it visually. Problem I am trying to solve: 1. Constructing the dependency graph Given the connectivity of the graph and a metric that determines how well a node depends on the other, order the dependencies. For instance, I could put in a few rules saying that node 3 depends on node 4 node 2 depends on node 3 node 3 depends on node 5 But because the final rule is not "valuable" (again based on the same metric), I will not add the rule to my system. 2. Execute the request order Once I built a dependency graph, execute the list in an order that maximizes the final connectivity. I am not sure if this is a really a problem but I somehow have a feeling that there might exist more than one order in which case, it is required to choose the best order. First and foremost, I am wondering if I constructed the problem correctly and if I should be aware of any corner cases. Secondly, is there a closely related algorithm that I can look at? Currently, I am thinking of something like Feedback Arc Set or the Secretary Problem but I am a little confused at the moment. Any suggestions? PS: I am a little confused about the problem myself so please don't flame on me for that. If any clarifications are needed, I will try to update the question.

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  • Which java technology should i use , if i want to build website with thousands of users

    - by Mirage
    Sorry for asking this question but i searched all java realted question but i got more confused. I am still not clear what should i start with 1)My main is build website in Java because someone told me that there are some machine learning or AI libraries available in java which i can use in java. so i decided to use that as it can reduce my work. Now i don't know java at all some people say following are used to build websites like 1)Servelts alone can build webiste 2)JSP alone can also build webiste 3)Struts 4)Spring with Hibernate 5)SEAM 6)JEE also for webistes Now guys i am confused where should i start from. Where does core JAVA fits in here. i was thinking of perhaps learning python as i know i have to learn Python only not its variations SO please guide me one thing which can solve my basic purpose of using ready made libraries of AI If i can do that with JSP then i will start with that. But i need to learn all of them then its better if can start learning python. I have 5 months to finish webiste. I really don't know why there are many braches of java for doing one thing Please help me.

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  • Cannot get new product attribute in grid display

    - by russjman
    I added a new attribute to my products(a boolean "yes/no" field). It is a variable to enable/disable the price from displaying on the product detail page, and grid view. I managed to get it work on the product info page. But on product grid page I cant seem to access that variable. Specifically, the template i am working with is catalog/product/price.phtml. From what i can tell, the price is being displayed by the same group of if-statements on both the product detail page, and grid page. This has me confused because i cant find any code on that template to handle multiple products, just a bunch of nested if statements. this is how im attempting to access this new variable using $_displayPrice. on line 36 of catalog/product/price.html <?php $_product = $this->getProduct(); ?> <?php $_id = $_product->getId() ?> <?php $_displayPrice = $_product->getDisplayPrice() ? "Yes" : "No"; echo $_displayPrice;?> What has me further confused is that when display $_product-getData(), my new variable isn't anywhere among that data. thanks in advance

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  • Codeigniter: db data in controller

    - by Kevin Brown
    I'm confused about what to do... I'm working on a user's page where they can view certain things only if their supervisor has given them "money" or "credits". I need a simple way to get the person that is their supervisor by doing something like: $data['employer'] = $this->home_model->getEmployees(array('user_id'=>$manager_id)); Basically, get the user information about a person who's user_id matches the manager_id of the currently logged in member. I don't know how to set the variable $manager_id. Additional Information: The current user has an id, and a manager_id. I need the id of the manager. So, I need to grab the manager_id of the logged-in user and find the manager who's user_id is that of the manager_id. What's the process to do this? I can get each individually, but I don't know how to use one to get the other... I know it is confusing, but I'm confused! Thanks for the help!

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  • Pointer initialization

    - by SoulBeaver
    Sorry if this question has been asked before. On my search through SO I didn't find one that asked what I wanted to know. Basically, when I have this: typedef struct node { int data; node *node; } *head; and do node *newItem = new node; I am under the impression that I am declaring and reserving space, but not defining, a pointer to struct node, is that correct? So when I do newItem->data = 100 and newItem->next = 0 I get confused. newItem = 0would declare what exactly? Both data and next? The object as a whole? I'm especially confused when I use typedef. Which part is the macro? I assume node because that's how I call it, but why do I need it? Finally, what happens when I do: node *temp; temp = new node; temp = head->next; head->next = newItem; newItem->next = temp; I mean, head-next is a pointer pointing to object newItem, so I assume not to newItem.data or next themselves. So how can I use an uninitialized pointer that I described above safely like here? is head now not pointing to an uninitialized pointer?

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  • Understanding Symbols In Ruby

    - by Kezzer
    Despite reading this article, I'm still confused as to the representation of the data in memory when it comes to using symbols. If a symbol, two of them contained in different objects, exist in the same memory location, then how is it that they contain different values? I'd have expected the same memory location to contain the same value. As a quote from the link: Unlike strings, symbols of the same name are initialized and exist in memory only once during a session of ruby I just don't understand how it manages to differentiate the values contained in the same memory location. EDIT So let's consider the example: patient1 = { :ruby => "red" } patient2 = { :ruby => "programming" } patient1.each_key {|key| puts key.object_id.to_s} 3918094 patient2.each_key {|key| puts key.object_id.to_s} 3918094 patient1 and patient2 are both hashes, that's fine. :ruby however is a symbol. If we were to output the following: patient1.each_key {|key| puts key.to_s} Then what will be output? "red", or "programming"? FURTHER EDIT I'm still really quite confused. I'm thinking a symbol is a pointer to a value. Let's forget hashes for a second. The questions I have are; can you assign a value to a symbol? Is a symbol just a pointer to a variable with a value in it? If symbols are global, does that mean a symbol always points to one thing?

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  • BackgroundWorker and instance variables

    - by Alastair Pitts
    One thing that's always confused me is how a BackgroundWorker seems to have thread-safe access to the instance variables of the surrounding class. Given a basic class: public class BackgroundProcessor { public List<int> Items { get; private set; } public BackgroundProcessor(IEnumerable<int> items) { Items = new List<int>(items); } public void DoWork() { BackgroundWorker worker = new BackgroundWorker(); worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted); worker.DoWork += new DoWorkEventHandler(worker_DoWork); worker.RunWorkerAsync(); } void worker_DoWork(object sender, DoWorkEventArgs e) { var processor = new ProcessingClass(); processor.Process(this.Points); //Accessing the instance variable } void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { //Stuff goes here } } Am I erroneous in my assumption the the call to processor.Process(this.Points); is a thread-safe call? How don't I get a cross-thread access violation? I'm sure it's obvious, but it always has confused me.

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  • Hibernate MapKeyManyToMany gives composite key where none exists

    - by larsrc
    I have a Hibernate (3.3.1) mapping of a map using a three-way join table: @Entity public class SiteConfiguration extends ConfigurationSet { @ManyToMany @MapKeyManyToMany(joinColumns=@JoinColumn(name="SiteTypeInstallationId")) @JoinTable( name="SiteConfig_InstConfig", joinColumns = @JoinColumn(name="SiteConfigId"), inverseJoinColumns = @JoinColumn(name="InstallationConfigId") ) Map<SiteTypeInstallation, InstallationConfiguration> installationConfigurations = new HashMap<SiteTypeInstallation, InstallationConfiguration>(); ... } The underlying table (in Oracle 11g) is: Name Null Type ------------------------------ -------- ---------- SITECONFIGID NOT NULL NUMBER(19) SITETYPEINSTALLATIONID NOT NULL NUMBER(19) INSTALLATIONCONFIGID NOT NULL NUMBER(19) The key entity used to have a three-column primary key in the database, but is now redefined as: @Entity public class SiteTypeInstallation implements IdResolvable { @Id @GeneratedValue(generator="SiteTypeInstallationSeq", strategy= GenerationType.SEQUENCE) @SequenceGenerator(name = "SiteTypeInstallationSeq", sequenceName = "SEQ_SiteTypeInstallation", allocationSize = 1) long id; @ManyToOne @JoinColumn(name="SiteTypeId") SiteType siteType; @ManyToOne @JoinColumn(name="InstalationRoleId") InstallationRole role; @ManyToOne @JoinColumn(name="InstallationTypeId") InstType type; ... } The table for this has a primary key 'Id' and foreign key constraints+indexes for each of the other columns: Name Null Type ------------------------------ -------- ---------- SITETYPEID NOT NULL NUMBER(19) INSTALLATIONROLEID NOT NULL NUMBER(19) INSTALLATIONTYPEID NOT NULL NUMBER(19) ID NOT NULL NUMBER(19) For some reason, Hibernate thinks the key of the map is composite, even though it isn't, and gives me this error: org.hibernate.MappingException: Foreign key (FK1A241BE195C69C8:SiteConfig_InstConfig [SiteTypeInstallationId])) must have same number of columns as the referenced primary key (SiteTypeInstallation [SiteTypeId,InstallationRoleId]) If I remove the annotations on installationConfigurations and make it transient, the error disappears. I am very confused why it thinks SiteTypeInstallation has a composite key at all when @Id is clearly defining a simple key, and doubly confused why it picks exactly just those two columns. Any idea why this happens? Is it possible that JBoss (5.0 EAP) + Hibernate somehow remembers a mistaken idea of the primary key across server restarts and code redeployments? Thanks in advance, -Lars

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  • Need some help understanding this problem

    - by Legend
    I was wondering if someone could help me understand this problem. I prepared a small diagram because it is much easier to explain it visually. Problem I am trying to solve: 1. Constructing the dependency graph Given the connectivity of the graph and a metric that determines how well a node depends on the other, order the dependencies. For instance, I could put in a few rules saying that node 3 depends on node 4 node 2 depends on node 3 node 3 depends on node 5 But because the final rule is not "valuable" (again based on the same metric), I will not add the rule to my system. 2. Execute the request order Once I built a dependency graph, execute the list in an order that maximizes the final connectivity. First and foremost, I am wondering if I constructed the problem correctly and if I should be aware of any corner cases. Secondly, is there a closely related algorithm that I can look at? Currently, I am thinking of something like Feedback Arc Set or the Secretary Problem but I am a little confused at the moment. Any suggestions? PS: I am a little confused about the problem myself so please don't flame on me for that. If any clarifications are needed, I will try to update the question.

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  • Stream PDF to another local App

    - by Nathan
    Hi, I'm currently trying to optimize a small firefox extension that will grab a pdf off the current document and send it to a port that another local application is listening on. Right now it uses a terrifying hackjob of cache viewer. The way I'm getting it is loading the cache, searching through it using the current URL and grabbing the file and saving it to a temp directory. Then I stream the file in, delete the temp, and send it through the socket. Now, my new design, ideally I'd want to build it from scratch and cut out saving it to the local machine at all, and just stream it through the socket. I've been looking at doing something like, //check page to ensure its a pdf //init in/out streams //stream through sock //flush Now, this would be vastly superior to the 400 line hacked up mess I have now, but I'm new to building FF extensions, and after reading a lot about URIs and the file streaming and such I'm probably more confused than when I started trying to fix this three hours ago. I'm okay with sending things through the sockets and whatnot, I understand that, I'm mainly confused about what multitude of interfaces I want to use. Gah! Thanks! Also, long time reader, first time poster!

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  • [Ruby] Object assignment and pointers

    - by Jergason
    I am a little confused about object assignment and pointers in Ruby, and coded up this snippet to test my assumptions. class Foo attr_accessor :one, :two def initialize(one, two) @one = one @two = two end end bar = Foo.new(1, 2) beans = bar puts bar puts beans beans.one = 2 puts bar puts beans puts beans.one puts bar.one I had assumed that when I assigned bar to beans, it would create a copy of the object, and modifying one would not affect the other. Alas, the output shows otherwise. ^_^[jergason:~]$ ruby test.rb #<Foo:0x100155c60> #<Foo:0x100155c60> #<Foo:0x100155c60> #<Foo:0x100155c60> 2 2 I believe that the numbers have something to do with the address of the object, and they are the same for both beans and bar, and when I modify beans, bar gets changed as well, which is not what I had expected. It appears that I am only creating a pointer to the object, not a copy of it. What do I need to do to copy the object on assignment, instead of creating a pointer? Tests with the Array class shows some strange behavior as well. foo = [0, 1, 2, 3, 4, 5] baz = foo puts "foo is #{foo}" puts "baz is #{baz}" foo.pop puts "foo is #{foo}" puts "baz is #{baz}" foo += ["a hill of beans is a wonderful thing"] puts "foo is #{foo}" puts "baz is #{baz}" This produces the following wonky output: foo is 012345 baz is 012345 foo is 01234 baz is 01234 foo is 01234a hill of beans is a wonderful thing baz is 01234 This blows my mind. Calling pop on foo affects baz as well, so it isn't a copy, but concatenating something onto foo only affects foo, and not baz. So when am I dealing with the original object, and when am I dealing with a copy? In my own classes, how can I make sure that assignment copies, and doesn't make pointers? Help this confused guy out.

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  • Hi, how can I use the check box group in JSF to select the items of database and generate a list in

    - by Alexzzy
    I am using netbean and JSF to do my project, recently I encountered a problem that confused me. The question: There is a set of check box groups that identify the artifacts from the nature, creator, period and school. And all the artifacts are stored in a table of database. I would like to select the items by nature or creator or something like that, and generate a list for the items selected in the next page. There are some tables of database for artifacts, nature, creators and school, and the type_ID(this is the nature), creator_ID, school_ID are the foreign keys in artifacts table. I have bound the tables with respective check boxes. For example, if I want to select nature is painting, creator is Davinci, school is Italian Renaissance, and then I click Search button. It will go to next page that generate a list of artifacts about all Italian Renaissance paintings created by Davinci. How can I do that? I was confused by JSF, but I have to use JSF to do my project. Anyone can help me plz??? Thank you very very much !!!!!!!

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  • problems with async jquery and loops

    - by Seth Vargo
    I am so confused. I am trying to append portals to a page by looping through an array and calling a method I wrote called addModule(). The method gets called the right number of times (checked via an alert statement), in the correct order, but only one or two of the portals actually populate. I have a feeling its something with the loop and async, but it's easier explained with the code: moduleList = [['weather','test'],['test']]; for(i in moduleList) { $('#content').append(''); for(j in moduleList[i]) { addModule(i,moduleList[i][j]); //column,name } } function addModule(column,name) { alert('adding module ' + name); $.get('/modules/' + name.replace(' ','-') + '.php',function(data){ $('#'+column).append(data); }); } for each array in the main array, I append a new column, since that's what each sub-array is - a column of portals. Then I loop through that sub array and call addModule on that column and the name of that module (which works correctly). Something buggy happens in my addModule method that it only adds the first and last modules, or sometimes a middle one, or sometimes none at all... im so confused!

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  • What are the responsibilities of the data layer?

    - by alimac83
    I'm working on a project where I had to add a data layer to my application. I've always thought that the data layer is purely responsible for CRUD functions ie. shouldn't really contain any logic but should simply retrieve data for the business layer to manipulate. However I'm a little confused with my project because I'm not sure whether I've structured my app correctly for this scenario. Basically I'm trying to retrieve a list of products from the database that fall within a certain pricing threshold. At the moment I have a function in my data layer that basically returns all products where price min threshold and price < max threshold. But it got me thinking that maybe this is incorrect. Should the data layer simply return a list of ALL products and then the business logic do the filtering? I'm pretty confused over whether the data layer should simply provide methods that allow the business layer to get raw data or whether it should be responsible for getting filtered data too? If anyone has an article or something explaining this in detail it'd be very helpful. Thanks

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  • How to re-prompt after a trap return in bash?

    - by verbose
    I have a script that is supposed to trap SIGTERM and SIGTSTP. This is what I have in the main block: trap 'killHandling' TERM And in the function: killHandling () { echo received kill signal, ignoring return } ... and similar for SIGINT. The problem is one of user interface. The script prompts the user for some input, and if the SIGTERM or SIGINT occurs when the script is waiting for input, it's confusing. Here is the output in that case: Enter something: # SIGTERM received received kill signal, ignoring # shell waits at blank line for user input, user gets confused # user hits "return", which then gets read as blank input from the user # bad things happen because of the blank input I have definitely seen scripts which handle this more elegantly, like so: Enter something: # SIGTERM received received kill signal, ignoring Enter something: # re-prompts user for user input, user is not confused What is the mechanism used to accomplish the latter? Unfortunately I can't simply change my trap code to do the re-prompt as the script prompts the user for several things and what the prompt says is context-dependent. And there has to be a better way than writing context-dependent trap functions. I'd be very grateful for any pointers. Thanks!

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  • Searching For A Record After A LINQ query

    - by Justin
    I'm confused to why this is happening. I'm new to LINQ so I'm clearly missing something here, that is probably pretty easy. I've looked up help on the topic, but I don't really know what to ask so I haven't found any answers that really address my question. This doesn't work It throws an EntityCommandExecutionException when the FirstOrDefault method is executed. var query = from band in context.BandsEntitySet where band.ID == 12345 select band; string venueName = "Willis Park"; foreach (var item in query) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } This works var query = from band in context.BandsEntitySet where band.ID == 12345 select band; var bandList = query.toList(); string venueName = "Willis Park"; foreach (var item in bandList) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } My question is simple: Why is the exception being thrown? And why does creating a list from the query allow me to use the FirstOrDefault method? Exception Message: A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll I guess I am wrong in my assumption that query is a list? Then what is it exactly? I'm confused because this doesn't throw an exception: foreach (var item in query) { var area = item.VenueArea; } I'd appreciate any help on this issue. thanks, Justin

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  • Concise description of how .h and .m files interact in objective c?

    - by RJ86
    I have just started learning objective C and am really confused how the .h and .m files interact with each other. This simple program has 3 files: Fraction.h #import <Foundation/NSObject.h> @interface Fraction : NSObject { int numerator; int denominator; } - (void) print; - (void) setNumerator: (int) n; - (void) setDenominator: (int) d; - (int) numerator; - (int) denominator; @end Fraction.m #import "Fraction.h" #import <stdio.h> @implementation Fraction -(void) print { printf( "%i/%i", numerator, denominator ); } -(void) setNumerator: (int) n { numerator = n; } -(void) setDenominator: (int) d { denominator = d; } -(int) denominator { return denominator; } -(int) numerator { return numerator; } @end Main.m #import <stdio.h> #import "Fraction.h" int main(int argc, char *argv[]) { Fraction *frac = [[Fraction alloc] init]; [frac setNumerator: 1]; [frac setDenominator: 3]; printf( "The fraction is: " ); [frac print]; printf( "\n" ); [frac release]; return 0; } From what I understand, the program initially starts running the main.m file. I understand the basic C concepts but this whole "class" and "instance" stuff is really confusing. In the Fraction.h file the @interface is defining numerator and denominator as an integer, but what else is it doing below with the (void)? and what is the purpose of re-defining below? I am also quite confused as to what is happening with the (void) and (int) portions of the Fraction.m and how all of this is brought together in the main.m file. I guess what I am trying to say is that this seems like a fairly easy program to learn how the different portions work with each other - could anyone explain in non-tech jargon?

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