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• Updating the collections of entities with NHibernate the correct way

  - by karel_evzen

  A simple question regarding how NHibernate works: I have a parent entity that has a collection of other child entities. Those child entities have a reference to the parent entity they belong to. Now I want to implement an Add method to the parent entity that would add a child to it. Should that Add method only add the child to its new parents collection, or should it also update the parent reference of the child or should it also remove the added entity from its previous parents collection? Do I have to do all these things in that method or will NHibernate do something for me? Thanks.

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• Do fields need to be explicitly final to have a "proper" immutable object?

  - by Yishai

  You often read about immutable objects requiring final fields to be immutable in Java. Is this in fact the case, or is it simply enough to have no public mutability and not actually mutate the state? For example, if you have an immutable object built by the builder pattern, you could do it by having the builder assign the individual fields as it builds, or having the builder hold the fields itself and ultimately return the immutable object by passing the values to its (private) constructor. Having the fields final has the obvious advantage of preventing implementation errors (such as allowing code to retain a reference to the builder and "building" the object multiple times while in fact mutating an existing object), but having the Builder store its data inside the object as it is built would seem to be DRYer. So the question is: Assuming the Builder does not leak the Object early and stops itself from modifying the object once built (say by setting its reference to the object as null) is there actually anything gained (such as improved thread safety) in the "immutability" of the object if the object's fields were made final instead?

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• Initializing a value through a Session variable

  - by William Calleja

  I need to Initialize a value in a Javascript by using a c# literal that makes reference to a Session Variable. I am using the following code <script type="text/javascript" language="javascript" > var myIndex = <%= !((Session["myIndex"]).Equals(null)||(Session["myIndex"]).Equals("")) ? Session["backgroundIndex"] : "1" %>; However the code above is giving me a classic Object reference not set to an instance of an object. error. Why? Shouldn't (Session["myIndex"]).Equals(null) capture this particular error?

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• Can't get a List(Of <my class>) from a Dictionary in .NET?

  - by magsto

  I have a Dictionary with key of type UInteger and the value is List(Of Session) where the (Public) class Session contains a couple of variables and a constructor (Public Sub New(...)). Some of the variables in my Session class is: Private count As Integer Private StartDate As Date Private Values As List(Of Integer) and a couple of methods like: Friend Sub Counter(ByVal c as Integer) count += c End Sub There is no problem to add values to the Dictionary: Dim Sessions As New List(Of Session) Dim dict As New Dictionary(Of Integer, Sessions) then some code to fill up a couple of Session objects in Sessions (not shown here) and then: dict.Add(17, Sessions) 'No problem Sessions.Clear() Sessions = dict(17) 'This doesn't return anything! The Sessions object is empty even if the code doesn't returned any error. Is my class Session to compex to be stored in a Dictionary?

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• Improve SQL query performance

  - by Anax

  I have three tables where I store actual person data (person), teams (team) and entries (athlete). The schema of the three tables is: In each team there might be two or more athletes. I'm trying to create a query to produce the most frequent pairs, meaning people who play in teams of two. I came up with the following query: SELECT p1.surname, p1.name, p2.surname, p2.name, COUNT(*) AS freq FROM person p1, athlete a1, person p2, athlete a2 WHERE p1.id = a1.person_id AND p2.id = a2.person_id AND a1.team_id = a2.team_id AND a1.team_id IN ( SELECT id FROM team, athlete WHERE team.id = athlete.team_id GROUP BY team.id HAVING COUNT(*) = 2 ) GROUP BY p1.id ORDER BY freq DESC Obviously this is a resource consuming query. Is there a way to improve it?

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• Objective C memory management question with NSArray

  - by Robert

  I am loading an array with floats like this: NSArray *arr= [NSArray arrayWithObjects: [NSNumber numberWithFloat:1.9], [NSNumber numberWithFloat:1.7], [NSNumber numberWithFloat:1.6], [NSNumber numberWithFloat:1.9],nil]; Now I know this is the correct way of doing it, however I am confused by the retail counts. Each Object is created by the [NSNumber numberWithFloat:] method. This gives the object a retain count of 1 dosnt it? - otherwise the object would be reclaimed The arrayWithObjects: method sends a retain message to each object. This means each object has a retain cont of 2. When the array is de-allocated each object is released leaving them with a retain count of 1. What have I missed?

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• Check constraint on table lookup

  - by bzamfir

  Hi, I have a table, department , with several bit fields to indicate department types One is Warehouse (when true, indicate the department is warehouse) And I have another table, ManagersForWarehouses with following structure: ID autoinc WarehouseID int (foreign key reference DepartmentID from departments) ManagerID int (foreign key reference EmployeeID from employees) StartDate EndDate To set new manager for warehouse, I insert in this table with EndDate null, and I have a trigger that sets EndDate for previous record for that warehouse = StartDate for new manager, so a single manager appears for a warehouse at a certain time. I want to add two check constraints as follows, but not sure how to do this do not allow to insert into ManagersForWarehouses if WarehouseID is not marked as warehouse Do not allow to uncheck Warehouse if there are records in ManagersForWarehouses Thanks

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• linq2sql left join with "multiselect"

  - by just_azho

  Hi, folks I'm trying to achieve following by linq2sql, but not successful. I've Member and Reference tables. DB is design in such a manner that Member can have multiple (=0) References. What I want as a result of query is, list (rows) of members, where all references of the member are "collected" in one column. What I had achieved is following query, but for this one there exist a row for each Reference. var refs = (from m in db.Members join r in db.References on m.PID equals r.PID into g from o in g.DefaultIfEmpty() select new { member = m, name = (o == null ? "" : o.NameSurname) }); I feel I need to insert SelectMany somewher :) Could you please give hints on achieving the goal?

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• Counting unknown numbers of chars from a file in C

  - by fang_dejavu

  I'm looking for a easy way to count the unknown number of characters in a file using C language. thanks for your help

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• Entity Framework with SQL Server 2000 (APPLY Operator) issue

  - by How Lun

  Hello, I have a simple Linq query below: var seq = (from n in GetObjects() select n.SomeKey) .Distinct() .Count(); This query works find with SQL Server 2005 and above. But, this start to give headache when I hooked the EF to SQL Server 2000. Because EF is using APPLY operator which only SQL Server 2005 and above can be supported. I do not know why the hell EF is using APPLy operator instead of sub queries. My current work around is: var seq = (from n in GetObjects() select n.SomeKey) .Distinct() .ToList() .Count(); But, I can forsee more problems to come. The above query is just a simple one. Did anyone come across such issue? And how you guys work around it? Or is there a way to force EF not to use APPLY operator? Any help will be very much appreciated. How Lun.

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• Java Error When correct code is put together

  - by Eric

  I have a few string problems that I need to put together for a complete homework assignment. They all work correctly by themselves, but when I put them together in the main function, the last one that finds the smallest word in a string gives an error. Anyone know why? public static void main(String[] args){ Scanner sc = new Scanner(System.in); //Length of Word String word1 = sc.next(); System.out.println(word1.length()); //Evens in one string odds in the other String word2 = sc.next(); StringBuilder even = new StringBuilder(); StringBuilder odd = new StringBuilder(); for(int i = 0; i < word2.length(); i++){ if(i % 2 == 0){ even.append(word2.charAt(i)); } else{ odd.append(word2.charAt(i)); } } System.out.println(even + " " + odd); //Diminishing Suffix String word3 = sc.next(); for(int j = 0; j < word3.length(); j++){ System.out.print(word3.substring(j, word3.length()) + " "); } System.out.printf("\n"); //Letter Replacement String word4 = sc.next(); String word5 = sc.next(); String word6 = sc.next(); String word7 = word4.replace(word5, word6); System.out.println(word7); //How many times x appears in xstring String word8 = sc.next(); String word9 = sc.next(); int index = word8.indexOf(word9); int count = 0; while (index != -1) { count++; word8 = word8.substring(index + 1); index = word8.indexOf(word9); } System.out.println(count); System.out.println(); //Lexicographically smallest word String Sentence = sc.nextLine(); String[] myWords = Sentence.split(" "); int shortestLengths, shortestLocation; shortestLengths=(myWords[1]).length(); shortestLocation=1; for (int i = 1; i <myWords.length; i++) { if ((myWords[i]).length() < shortestLengths) { shortestLengths=(myWords[i]).length(); shortestLocation=i; } } System.out.println(myWords[shortestLocation]); } } Talking about the lexicographically smallest one

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• Singleton wrapper for Context

  - by kpdvx

  I'm considering creating a singleton wrapper for a Context so my model objects, if necessary, can open and read from a database connection. My model objects do not have access to a Context, and I'd like to avoid needing to pass a reference to a Context from object to object. I was planning to place into this singleton a reference to the Context returned by Application.getApplicationContext(). This singleton object would be initialized in my custom Application instance before anything else would need to or have a chance to use it. Can anyone think of a reason to not do this?

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• Flex: Problem with CollectionEvent on ArrayCollection

  - by dasnervtdoch

  Hi there, got a reference to an arrayCollection and add event listener like this: collection.addEventListener(CollectionEvent.COLLECTION_CHANGE, onCollectionChange); that´s fine. Now some other component does have the same reference and is adding items to and removing items from that collection. Each time the handler is called: private function onProjectPersonsChange(event:Event):void { if (event.kind == CollectionEventKind.ADD) { //do something } else if (event.kind == CollectionEventKind.REMOVE) { //do something //here is the problem: event.items.length = 0 } else { trace('CollectionEvent: kind not handled!'); } } Does somebody know why the removed item is not in 'items'? Thanks in advance!

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• XPath to find an element with a similar sibling

  - by user364902

  Suppose I have this XML: <x> <e a='1' b='A'/> <e a='1' b='B'/> <e a='1' b='A'/> </x> I'd like to write an xpath to find any elements e which: Have attribute @b = 'A' Have the same value for attribute @a The xpath can't reference the literal value of attribute @a, however. It can reference the literal value of attribute @b. Or more generally, I want to find if there are any instances where there are two or more elements e[@b=A'] with the same value for attribute @a. Is this possible?

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• How many Stored Procedures created everyday ( problem in converting Datetime )?

  - by Space Cracker

  I make a query that return to me the count of Stored Procedure that created everyday as follow SELECT convert(varchar, crdate, 103) as Date,Count(*) as Counter FROM sysobjects WHERE (xtype = 'p') AND (name NOT LIKE 'dt%') Group by convert(varchar, crdate, 103) and its already work but dates appear in string format that i can't order it such as below 01/03/2010 3 01/04/2008 4 01/05/2010 5 01/11/2008 1 01/12/2008 4 02/03/2008 1 02/03/2010 2 02/04/2008 4 02/05/2010 2 02/11/2008 2 02/11/2009 2 02/12/2008 4 03/01/2010 1 03/02/2010 2 03/03/2010 2 03/04/2008 2 03/04/2010 2 03/05/2008 1 03/05/2010 2 I want to make that in which date is in datetime format that i can make order by successfully, i tried convert(datetime, crdate, 103) but it show Full date any idea of how to do ?

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• How to remove row which has one or more empty or null cell ?

  - by Harikrishna

  I have datagridview on my winform. I am displaying records in the datagridview. Now after displaying the records on the datagridview, I want to remove the row from datagridview which has one or more empy cells that is no value in the cell for that row. So for that I am checking each cell for every row if there is any cell empty or null then I remove that rows using RemoveAt() function. My code is : for (int i = 0; i < dataGridView1.Rows.Count - 1; i++) { for (int j = 0; j < dataGridView1.Columns.Count; j++) { if (string.IsNullOrEmpty(dataGridView1.Rows[i].Cells[j].Value.ToString())) { dataGridView1.Rows.RemoveAt(i); break; } } }

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• MySQL UPDATE WHERE IN for each listed value separately?

  - by Tom

  Hi, I've got the following type of SQL: UPDATE photo AS f LEFT JOIN car AS c ON f.car_id=c.car_id SET f.photo_status=1 , c.photo_count=c.photo_count+1 WHERE f.photo_id IN ($ids) Basically, two tables (car & photo) are related. The list in $ids contains unique photo ids, such as (34, 87, 98, 12). With the query, I'm setting the status of each photo in that list to "1" in the photo table and simultaneously incrementing the photo count in the car table for the car at hand. It works but there's one snag: Because the list can contain multiple photo ids that relate to the same car, the photo count only ever gets incremented once. If the list had 10 photos associated with the same car, photo_count would become 1 .... whereas I'd like to increment it to 10. Is there a way to make the incrementation occur for each photo individually through the join, as opposed to MySQL overthinking it for me? I hope the above makes sense. Thanks.

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• How can we compute the LAST page with JPA?

  - by Kevin

  I would like to implement pagination in my Servlet/EJB/JPA-Hibernate project, but I can't figure out how only one page from the query and know the number of pages I must display I use setFirstResult(int first) ; setMaxResults(int max) ; and that's working alright, but how can I know how many pages I will have in total? (Hibernate is my JPA provider, but I would prefer using only JPA if possible) UPDATE: COUNT() seems to be the better/easiest solution; but what can be the cost of SELECT COUNT(*) FROM ... in comparison with executeQuery("SELECT * FROM ...).getListResult().size() ?

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• Duplicate array but maintain pointer links

  - by St. John Johnson

  Suppose I have an array of nodes (objects). I need to create a duplicate of this array that I can modify without affecting the source array. But changing the nodes will affect the source nodes. Basically maintaining pointers to the objects instead of duplicating their values. // node(x, y) $array[0] = new node(15, 10); $array[1] = new node(30, -10); $array[2] = new node(-2, 49); // Some sort of copy system $array2 = $array; // Just to show modification to the array doesn't affect the source array array_pop($array2); if (count($array) == count($array2)) echo "Fail"; // Changing the node value should affect the source array $array2[0]->x = 30; if ($array2[0]->x == $array[0]->x) echo "Goal"; What would be the best way to do this?

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• Subtype polymorphism and arrays

  - by user133466

  Computer[] labComputers = new Computer[10]; with public class Computer { ... void toString(){ // print computer specs } } public class Notebook extends Computer{ ... void toString(){ // print computer specs + laptop color } } each subscripted variable labComputers[i] can reference either a Computer object or a Notebook object because Notebook is a subclass of Computer. For the method call labComputers[i].toString(), polymorphism ensures that the correct toString method is called. I wonder what if we do Notebook[] labComputers = new Notebook[10]; what kind or error would I get if I reference with Computer object and a Notebook object

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• How to expose information about a running .NET exe?

  - by Doug

  I have a .NET exe that I wrote and it has a couple properties that I made public and want to expose. I want to shell this exe (Process.Start()) and then somehow reference this exe and get access to these public properties. These properties expose information about the running exe. I know how to shell to the exe. And I know how to add a reference to the exe from my project that I want to use this object. But how do I get access to the properties of this running exe? I hope I am explaining myself well. If you do know the answer maybe you could just tell me what the standard method is to expose properties of a running exe to another application at run-time. Thanks for any help!

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• Oracle date / order by question

  - by user561793

  I want to select a date from oracle table formatted like select (to_char(req_date,'MM/YYYY')) but I also want to order the result set on this date format. I want them to be ordered like dates not strings. Like this 09/2009 10/2009 11/2009 12/2009 01/2010 02/2010 03/2010 04/2010 05/2010 06/2010 07/2010 08/2010 09/2010 10/2010 11/2010 12/2010 Not like 01/2010 02/2010 03/2010 04/2010 05/2010 06/2010 07/2010 08/2010 09/2009 09/2010 10/2009 10/2010 11/2009 11/2010 12/2009 12/2010 Any way to do this in sql? full sql is select (to_char(req_date,'MM/YYYY')) as monthYear,count(req_id) as count from REQUISITION_CURRENT t group by to_char(req_date,'MM/YYYY') Thanks

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• Index is outside the bounds of the array

  - by coffeeaddict

  Ok, I cannot get this. I've looked at it and I don't see why it's out of bounds. I get the error at paypalItems[paypalItems.Length] = new PaymentDetailsItemType PaymentDetailsItemType[] paypalItems = new PaymentDetailsItemType[order.OrderItems.Count]; for (int i = 0; i < order.OrderItems.Count; i++) { paypalItems[i] = new PaymentDetailsItemType { Name = order.OrderItems[i].Name, Amount = ApiUtility.CreateBasicAmount(order.OrderItems[i].Price), Description = order.OrderItems[i].Name, Number = order.OrderItems[i].Sku, }; } if (giftCardsTotal != 0) { // add Coupons & Discounts line item paypalItems[paypalItems.Length] = new PaymentDetailsItemType { Name = "Gift Cards", Amount = ApiUtility.CreateBasicAmount(giftCardsTotal), Description = "Gift Cards" }; }

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• How to identify each parameter type in a C# method?

  - by user465876

  I have a C# method say: MyMethod(int num, string name, Color color, MyComplexType complex) Using reflection, how can I distinctly identify each of the parameter types of any method? I want to perform some task by parameter type. If the type is simple int, string or boolean then I do something, if it is Color, XMLDocument, etc I do something else and if it is user defined type like MyComplexType or MyCalci etc then I want to do certain task. I am able to retrieve all the parameters of a method using ParameterInfo and can loop through each parameter and get their types. But how can I identify each data type? foreach (var parameter in parameters) { //identify primitive types?? //identify value types //identify reference types } Edit: this is apart of my code to create a propert grid sort of page where I want to show the parameter list with data types for the selected method. If the parameter has any userdefined type/reference type then I want to expand it further to show all the elements under it with datatypes.

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• returning an abstract class from a function

  - by cemregoksu

  Is it possible to return an abstract class(class itself or a reference, doesn't matter) from a function?

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