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• iPhone , core data, whether NSManagedObject use lazy load mechanism when it was create ?

  - by Robin

  Hi, all, I have use core data in app, I have definite a class that most like as follows: @interface Master : NSManagedObject { } @property (nonatomic, retain) NSSet* Details; .... the entity Master contains a property 'Details' that is relate to another table, this is typical Master-Details relationship, I trace the app , but I find a issue that the property 'Details' value was construct even it never be invoked ..... but I consider that the core data 'should' use some lazy mechanism to improve performance, or maybe I miss some configure step ? because the Master entity contains at least five 'Child' table properties , I have to consider this problem before use the core data .... any help ? thanks for your time!

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• Using Rails and Rspec, how do you test that the database is not touched by a method

  - by Will Tomlins

  So I'm writing a test for a method which for performance reasons should achieve what it needs to achieve without using SQL queries. I'm thinking all I need to know is what to stub: describe SomeModel do describe 'a_getter_method' do it 'should not touch the database' do thing = SomeModel.create something_inside_rails.should_not_receive(:a_method_querying_the_database) thing.a_getter_method end end end EDIT: to provide a more specific example: class Publication << ActiveRecord::Base end class Book << Publication end class Magazine << Publication end class Student << ActiveRecord::Base has_many :publications def publications_of_type(type) #this is the method I am trying to test. #The test should show that when I do the following, the database is queried. self.publications.find_all_by_type(type) end end describe Student do describe "publications_of_type" do it 'should not touch the database' do Student.create() student = Student.first(:include => :publications) #the publications relationship is already loaded, so no need to touch the DB lambda { student.publications_of_type(:magazine) }.should_not touch_the_database end end end So the test should fail in this example, because the rails 'find_all_by' method relies on SQL.

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• Which PSU should I chose? The biggest is the best?

  - by Shiki

  I'm fully aware of PSU's "Active PFC" and that they won't consume the written W all the time. (Makes sense). But now I'm before a PSU replacement (Guys: NEVER buy a Chieftec. Seriously.) The question is: If one can get a bigger one (in my case 750W and 650W) ... should that person go for the bigger one ? (The difference in price is not much). No, I don't think I'll soon use all that much. (Help (if you want of course) to make the question more generic if the question is really not OK in this form. I've been wondering about this for a time already. In my case it would be XFX Black Edition Silver 750W and 650W)

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• Best way to model Customer <--> Address

  - by Jen

  Every Customer has a physical address and an optional mailing address. What is your preferred way to model this? Option 1. Customer has foreign key to Address Customer (id, phys_address_id, mail_address_id) Address (id, street, city, etc.) Option 2. Customer has one-to-many relationship to Address, which contains a field to describe the address type Customer (id) Address (id, customer_id, address_type, street, city, etc.) Option 3. Address information is de-normalized and stored in Customer Customer (id, phys_street, phys_city, etc. mail_street, mail_city, etc.) One of my overriding goals is to simplify the object-relational mappings, so I'm leaning towards the first approach. What are your thoughts?

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• CakePHP HABTM Filtering

  - by James Haigh

  Hi, I've got two tables - users and servers, and for the HABTM relationship, users_servers. Users HABTM servers and vice versa. I'm trying to find a way for Cake to select the servers that a user is assigned to. I'm trying things like $this->User->Server->find('all'); which just returns all the servers, regardless of whether they belong to the user. $this->User->Server->find('all', array('conditions' => array('Server.user_id' => 1))) just gives an unknown column SQL error. I'm sure I'm missing something obvious but just need someone to point me in the right direction. Thanks!

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• Several devices in Device Manager have Code 3 error

  - by John Straka

  One of our users' machines (Dell Optiplex 380 running Windows 7 32-bit) is having a weird driver issue. A bunch of devices have Error Code 3: The driver for this device might be corrupted, or your system may be running low on memory or other resources. (Code 3) The system isn't low on memory (only 1GB in use out of whatever the max for 32-bit is.) Here's a screenshot of the affected devices: I tried reinstalling the chipset and audio drivers to no avail. I have no idea what prompted it, and I'm not sure how the basic Windows Generic PnP Monitor driver could even be corrupted. What might be causing this error?

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• Mapping enum to a table with hibernate annotation

  - by Thierry-Dimitri Roy

  I have a table DEAL and a table DEAL_TYPE. I would like to map this code: public class Deal { DealType type; } public enum DealType { BASE("Base"), EXTRA("Extra"); } The problem is that the data already exist in the database. And I'm having a hard time mapping the classes to the database. The database looks something like that: TABLE DEAL { Long id; Long typeId; } TABLE DEAL_TYPE { Long id; String text; } I know I could use a simple @OneToMany relationship from deal to deal type, but I would prefer to use an enum. Is this possible? I almost got it working by using a EnumType.ORDINAL type. But unfortunately, my IDs in my deal type table are not sequential, and do not start at 1. Any suggestions?

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• Random timeout now and then

  - by KenavR

  Maybe this is a to generic question, but since we have this issue for quite a while now, I give it a shot. We have some applications which use HTTP for the connection between the client (website or fat-client) and the server. The Computer who runs this applications is in a Network behind a firewall and a proxy, the server isn't inside the same network. The problem is that every now and then the https Request times out and depending on the Client the Application "hangs" or does some other funky stuff. The problem is definitely inside our network, because if i try the applications outside our network it works fine. Can you give me a hint where i can most likely find the problem?

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• Symfony 1.4: Deleting a sfGuardUser

  - by Tom

  Hi, I'm having some trouble with the following... I have a sfGuardUser table set up normally, and it has a one-to-one relationship with a Profile table, which contains some additional user info. When a user wants to delete themselves from the site, I'd like to retain their info in the Profile table for various purposes BUT delete the sfGuardUser in order to keep that table cleaner/shorter (not just set it to inactive). I was under the impression that I could set the FK in the Profile table to NULL and then delete the sfGuardUser, but it seems the FK-constraint fails. Indeed, it seems I can't delete either and the queries fail: If I try to delete the sfGuardUser, the Profile table will have an invalid FK If I try to delete a Profile, the sfGuardUser will have an invalid FK Other than leaving outdated sfGuardUsers and Profiles in these tables, or having to use a cascaded delete to get rid of both, can anyone tell me if there's any other way around this? Thank you.

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• Installing maven on Ubuntu by manual download

  - by WebDevHobo

  To install Maven, I downloaded the latest version from the website and then followed these steps: http://maven.apache.org/download.html#Installation The last step, the version control, does not work. It says that 'mvn' is currently not installed and that I should type sudo apt-get install maven2 If I go directly to the mvn file itself, it does work: root@ubuntu:~# /usr/local/apache-maven/apache-maven-2.2.1/bin/mvn --version Apache Maven 2.2.1 (r801777; 2009-08-06 12:16:01-0700) Java version: 1.6.0_21 Java home: /usr/java/jdk1.6.0_21/jre Default locale: en_US, platform encoding: UTF-8 OS name: "linux" version: "2.6.32-25-generic" arch: "i386" Family: "unix" So, what am I doing wrong here? Or what would and apt-get install do extra that I might have forgotten?

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• How to: Display multiple related classes in an ASP.NET GridView ?

  - by kversch

  I would like to display students and their grades with a GridView and LinqToSQL like this: assignment1 assignment2 Student 1 55 89 Student 2 87 56 Student 3 92 34 I found this topic but it doesn't answer my question: http://forums.asp.net/t/1557987.aspx I have a many-to-many relationship between students and assignments called "grades". The grade for the assignment is stored in that table in a "gradeNumber" column. I would also like to specify which assignments should be displayed in the grid. Btw, my LINQ entities are extended to allow me to write/get studentx.Assignments or assignmentx.Students.

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• JPA and aggregate functions. How do I use the result of the query?

  - by Bogdan

  Hey guys, I'm new to ORM stuff and I need some help understanding something. Let's assume I have the following standard SQL query: SELECT *, COUNT(test.testId) AS noTests FROM inspection LEFT JOIN test ON inspection.inspId = test.inspId GROUP BY inspection.inspId which I want to use in JPA. I have an Inspection entity with a one-to-many relationship to a Test entity. (an inspection has many tests) I tried writing this in JPQL: Query query = em.createQuery("SELECT insp, COUNT(???what???) FROM Inspection insp LEFT JOIN insp.testList " + "GROUP BY insp.inspId"); 1) How do I write the COUNT clause? I'd have to apply count to elements from the test table but testList is a collection, so I can't do smth like COUNT(insp.testList.testId) 2) Assuming 1 is resolved, what type of object will be returned. It will definitely not be an Inspection object... How do I use the result?

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• Howto check if a object is connected to another in hibernate

  - by codevourer

  Imagine two domain object classes, A and B. A has a bidirectional one-to-many relationship to B. A is related to thousands of B. The relations must be unique, it's not possible to have a duplicate. To check if an instance of B is already connected to a given instance of A, we could perform an easy INNER JOIN but this will only ensure the already persisted relations. What about the current transient relations? class A { @OneToMany private List<B> listOfB; } If we access the listOfB and perform a check of contains() this will fetch all the connected instances of B lazy from the datasource. I only want to validate them by their primary-key. Is there an easy solution where I can do things like "Does this instance of A is connected with this instance of B?" Without loading all these data into memory and perform a based on collections?

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• Physical Cores vs Virtual Cores in Parallelism

  - by Code Curiosity

  When it comes to virtualization, I have been deliberating on the relationship between the physical cores and the virtual cores, especially in how it effects applications employing parallelism. For example, in a VM scenario, if there are less physical cores than there are virtual cores, if that's possible, what's the effect or limits placed on the application's parallel processing? I'm asking, because in my environment, it's not disclosed as to what the physical architecture is. Is there still much advantage to parallelizing if the application lives on a dual core VM hosted on a single core physical machine?

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• Syntax error in INSERT INTO statement

  - by user454563

  I wrote a program that connects to MS Access. When I fill in the fields and add a new item to Access the program fails. The exception is "Syntax error in INSERT INTO statement" Here is the relevant code. **************************************************************** AdoHelper.cs **************************************************************** using System; using System.Collections.Generic; using System.Text; using System.Data; using System.Data.OleDb; namespace Yad2 { class AdoHelper { //get the connection string from the app.config file //Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\Yad2.accdb static string connectionString = Properties.Settings.Default.DBConnection.ToString(); //declare the db connection static OleDbConnection con = new OleDbConnection(connectionString); /// <summary> /// To Execute queries which returns result set (table / relation) /// </summary> /// <param name="query">the query string</param> /// <returns></returns> public static DataTable ExecuteDataTable(string query) { try { con.Open(); OleDbCommand command = new OleDbCommand(query, con); System.Data.OleDb.OleDbDataAdapter tableAdapter = new System.Data.OleDb.OleDbDataAdapter(command); DataTable dt = new DataTable(); tableAdapter.Fill(dt); return dt; } catch (Exception ex) { throw ex; } finally { con.Close(); } } /// <summary> /// To Execute update / insert / delete queries /// </summary> /// <param name="query">the query string</param> public static void ExecuteNonQuery(string query) { try { con.Open(); System.Data.OleDb.OleDbCommand command = new System.Data.OleDb.OleDbCommand(query, con); command.ExecuteNonQuery(); } catch (Exception ex) { throw ex; } finally { con.Close(); } } /// <summary> /// To Execute queries which return scalar value /// </summary> /// <param name="query">the query string</param> public static object ExecuteScalar(string query) { try { con.Open(); System.Data.OleDb.OleDbCommand command = new System.Data.OleDb.OleDbCommand(query, con); /// here is the Excaption !!!!!!!!! return command.ExecuteScalar(); } catch { throw; } finally { con.Close(); } } } } **************************************************************************** **************************************************************************** DataQueries.cs **************************************************************************** using System; using System.Collections.Generic; using System.Text; using System.Data; namespace Yad2 { class DataQueries { public static DataTable GetAllItems() { try { string query = "Select * from Messages"; DataTable dt = AdoHelper.ExecuteDataTable(query); return dt; } catch (Exception ex) { throw ex; } } public static void AddNewItem(string mesNumber, string title , string mesDate , string contactMail , string mesType , string Details ) { string query = "Insert into Messages values(" + mesNumber + " , '" + title + "' , '" + mesDate + "' , '" + contactMail + "' , , '" + mesType + "' , '" + Details + "')"; AdoHelper.ExecuteNonQuery(query); } public static void DeleteDept(int mesNumber) { string query = "Delete from Item where MessageNumber=" + mesNumber; AdoHelper.ExecuteNonQuery(query); } } } *********************************************************************************************** plase help me .... why the program falls ?

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• Grails - Need to restrict fetched rows based on condition on join table

  - by sector7

  Hi guys, I have these two domains Car and Driver which have many-to-many relationship. This association is defined in table tblCarsDrivers which has, not surprisingly, primary keys of both the tables BUT additionally also has a new boolean field deleted. Herein lies the problem. When I find/get query on domain Car, I am fetched all related drivers irrespective of their deleted status in tblCarsDrivers, which is expected. I need to put a clause/constraint to exclude the deleted drivers from the list of fetched records. PS: I tried using an association domain CarDriver in joinTable name but that seems not to work. Apparently it expects only table names, not maps. PPS: I know its unnatural to have any other fields besides the mapping keys in mapping table but this is how I got it and it cant be changed. Car domain is defined as such - class Car { Integer id String name static hasMany = [drivers:Driver] static mapping = { table 'tblCars' version false drivers joinTable:[name: 'tblCarsDrivers',column:'driverid',key:'carid'] } } Thanks!

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• How would you create a notification system like on SO or Facebook in RoR?

  - by Justin Meltzer

  I'm thinking that notifications would be it's own resource and have a has_many, through relationship with the user model with a join table representing the associations. A user having many notifications is obvious, and then a notification would have many users because there would be a number of standardized notifications (a commenting notification, a following notification etc.) that would be associated with many users. Beyond this setup, I'm unsure how to trigger the creation of notifications based on certain events in your application. I'm also a little unsure of how I'd need to set up routing - would it be it's own separate resource or nested in the user resource? I'd find it very helpful if someone could expand on this. Lastly, ajax polling would likely improve such a feature. There's probably some things I'm missing, so please fill this out so that it is a good general resource.

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• I get "stack level too deep" error when using a named scope

  - by Brian Roisentul

  I'm using ruby on rails 2.3.8 and when I write the syntax shown below I get the "stack level too deep" error message. The model is called Announcement and the line of the error looks like this: Tag.find(category_id).announcements.published Where published is named_scope :published, :conditions => "announcements.state = 'published'" I use this named scope in many other places and it works fine. What am I doing wrong? (the relationship between Tag and Announcement model is ok because if I remove the ".published" method from that line it works just fine).

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• Installing a personal security certificate for Windows Server 2008 Terminal Services user

  - by Rick

  We use StoneEdge Order Manager, which runs under Microsoft Access, on several Windows computers as well as through Terminal Services on Windows Server 2008. Terminal Services users are unable to process credit cards using the First Data Global Gateway on the server. We have followed the necessary setup instructions provided under the user account, which involves adding a certificate in the Internet Options control panel. The Windows XP desktops require this to be done, or a generic 'unable to connect' message is shown when attempting to charge a card. On the server, this message is shown regardless of whether the certificate has been installed. Is there anything else that needs to be done that is specific to Windows Server that is not mentioned in the workstation instructions? Setup Instructions

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• Core Data Predicate To Many

  - by Vikings

  I have a core data model that has a one to many relationship, there is a category, and it can contain many subcategories. Category <---- Subcategory I am trying to perform a fetch that checks if a particular Category contains a Subcategory with a particular name. Let's say I have two categories below, I want to fetch to see if there are any subcategories name "Apple" in the Category named "Fruits". Vetegables - Carrot - Lettuce Fruits - Apple - Orange - Pear Code: - (SubCategory *)searchForSubCategoryWithName:(NSString *)subCategory inCategory:(Category *)category { NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"SubCategory" inManagedObjectContext:self.beer.managedObjectContext]; [fetchRequest setEntity:entity]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name == [c] %@", subCategory]; [fetchRequest setPredicate:predicate]; NSError *error; NSArray *fetchedObjects = [self.beer.managedObjectContext executeFetchRequest:fetchRequest error:&error]; if (fetchedObjects != nil && fetchedObjects.count > 0) { return [fetchedObjects objectAtIndex:0]; } else { return nil; } }

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• After C++ - Python or Java?

  - by carleeto

  I'm fast approaching the point in my coding where I would like to quickly write object oriented code in languages other than C++ for a variety of reasons. After a lot of research, my choices have pretty much narrowed down to Python and Java. I'm leaning towards Python because of its relationship to C, but with Java, from what I can see, I get a good introduction to using and creating test suites with Eclipse - there is also Processing which is pulling me towards Java. I'm not the kind of guy to tackle two languages at once, so which one would you recommend and why? What I want at the end is to have an additional language I can use for rapid development. Ease of learning isn't important to me as I'm willing to put in the time regardless. Ability to use the new language widely is.

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• Reduce the number of queries in EF

  - by Gio2k

  I have the following Model: Entities: Product (Contains basic data for products: price, etc) Attribute (Contains data for all possible optional attributes) ProductAttribute (Contains data for optional attributes of a product, eg. Color, Model, Size). ProductAttribute is essentially a many to many relationship with payload (ProductId, AttributeID, Value) And this piece of code: private static void ListAttributes(Product p) { p.ProductAttributes.Load(); foreach (var att in p.ProductAttributes) { att.Attribute.load(); Console.WriteLine("\tAttribute Name:{0} - Value {1}", att.Attribute.Name, att.AttributeValue); } } This piece of code will fire a query for each time the att.Attribute.Load() method is called in the foreach loop, only so i can get display the name of the attribute. I would like to fetch the Attribute.Name together with the query that fetches all attribute values, i.e. join ProductAttribute and Attribute. Is there any way to achieve this within my method?

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• 'Recursive' LINQ calls

  - by Sir Psycho

  Hi, I'm trying to build an XML tree of some data with a parent child relationship, but in the same table. The two fields of importance are CompetitionID ParentCompetitionID Some data might be CompetitionID=1, ParentCompetitionID=null CompetitionID=2, ParentCompetitionID=1 CompetitionID=3, ParentCompetitionID=1 The broken query I have simply displays results in a flat format. Seeing that I'm working with XML, some sort of recursive functionality is required. I can do this using recursion, but would like to see the linq version. Any help appreciated. var results = from c1 in comps select new { c.CompetitionID, SubComps= from sc in comps.Where (c2 => c2.CompetitionID == c1.CompetitionID) select sc };

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• Hard Disk recovery

  - by Shaihi

  I have 3 disks of the same type model and year of production. All the disks were used part of a generic solution of an IBM server solution. My problem is that all 3 disks suffered the same malfunction at the same exact time and are now dis-functional. I went to two different expert's laboratories and got the same answer: To recover the data they need another identical disk from which they can take spare parts. Can my case really be that clinical? Anyway, I am not sure if this question belongs to this forum, but I am looking to buy the following disk: IIBM ESERVER XSERIES IBM P/N 24P3707 IBM FRU 24P3708 146.8GB USCSI 10K RPM PART NOMBER 9V2005-027 I already bought a disk with the same part number, but the labs said that apparently I need a disk that was manufactured in the same factory. That means that all the numbers have to be exactly the same. If anybody know where I can purchase such a disk (the information on the lost disks is really important to me), please tell me the place.

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• Navigating by foreign keys in ADO.NET Entity Framework/MySQL

  - by Werg38

  I am using ASP.NET MVC2 on top of a MySQL database in VS2008. I am using the MySQL ADO.NET connector 6.2.3 to provide the connection for the ADO.NET Entity Data Model. This is mostly working ok, however navigating via foreign keys is causing me a real headache! Here is a simplified example.. Car (Table) CarID PK Colour Doors ManufacturerID FK Manufacturer (Table) ManufacturerID PK Name In the edmx file I can see the 1-many relationship shown as a navigation property in the both the Car and Manufacturer tables. I create a Models.CarRepository that allows me to returns a IQueryable. At the View I want to be able to display the Manufacturer.Name for each car. This is not accessible via the object I get returned. What is best way to implement this? Have I encountered a limitation of the Entity Framework/MySQL combination?

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