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  • C++ Dynamic object construction

    - by Rajesh Subramanian
    I have a base class, class Msg { ParseMsg() { ParseMsgData(); ParseTrailer(); } virtual void ParseMsgData() = 0; ParseTrailer(); }; and derived classes, class InitiateMsg { void ParseMsgData() { ... } }; class ReadOperationMsg { void ParseMsgData() { ... } }; class WriteOperationMsg { void ParseMsgData() { ... } }; and the scenario is below, void UsageFunction(string data) { Msg* msg = ParseHeader(data); ParseMsg } Msg* ParseHeader(string data) { Msg *msg = NULL; .... switch() { case 1: msg = new InitiateMsg(); break; case 2: msg = new ReadOperationMsg{(); break; case 3: msg = new WriteOperationMsg{(); break; .... } return msg; } based on the data ParseHeader method will decide which object has to be created, So I have implemented ParseHeader function outside the class where I am using. How can I make the ParseHeader function inside the Msg class and then use it? In C# the same is achieved by defining ParseHeader method as static with in class and use it from outside,

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  • Copy object using pointer (templates)

    - by Azodious
    How the push_back of stl::vector is implemented so it can make copy of any datatype .. may be pointer, double pointer and so on ... I'm implementing a template class having a function push_back almost similar to vector. Within this method a copy of argument should be inserted in internal memory allocated memory. but the argument is a pointer. (an object pointer). Can you pls tell how to create copy from pointer. so that if i delete the pointer in caller still the copy exists in my template class? Code base is as follows: template<typename T> class Vector { public: void push_back(const T& val_in) { T* a = *(new T(val_in)); m_pData[SIZE++] = a; } } Caller: Vector<MyClass*> v(3); MyClass* a = new MyClass(); a->a = 0; a->b = .5; v.push_back(a); delete a; Thanks.

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  • object references an unsaved transient instance

    - by developer
    Hi, I have 2 tables, user and userprofile, both with almost identical fields. user table references userprofile table by primary key ID. My requirement is that on click of a button I need to dump user table record to userprofile table. Now for a particular user table, if there is a corresponding userprofile entry, I am successfully able to dump the data, but if there is no record in userprofile table then I need to create a new record by dumping all the data. My problem is that I am able to update the data when the record is present in userprofile table, but in the case wherein I have to create a new record I get the below error "object references an unsaved transient instance - save the transient instance before flushing". `<class name="User"> <id name="ID" type="Int32"> <generator class="native" /> </id> <many-to-one name="Pid" class="UserProfile" /> </class>` UserProfile is another table and Pid above references the Primary key ID of UserProfile table.

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  • Limiting object allocation over multiple threads

    - by John
    I have an application which retrieves and caches the results of a clients query. The client then requests different chunks of data and the application sends the relevant results and removes them from the cache. A new requirement for this application is that there needs to be a run-time configurable maximum number of results which may be cached. I've taken the naive approach and implemented this by using a counter under a lock which is incremented every time a result is cached and decremented whenever a result is removed from the cache. Unfortunately, this has drastically reduced the applications performance when processing a large number of concurrent requests. I have tried both a critical section lock and spin-lock; the performance improves a bit with a spin-lock, but is still unacceptably slow. Is there a better way to solve this problem which may improve performance? Right now I have a thread pool that services requests and each request is tied to a Request object which stores that cached results for that particular request. Here is a simplified pseudo code version of my current implementation: void ResultCallback( Result result, Request *request ) { lock totalResultsCached lock cachedLimit if( totalResultsCached + 1 > cachedLimit ) { unlock cachedLimit unlock totalResultsCached //cancel the request return; } ++totalResultsCached; unlock cachedLimit unlock totalResultsCached request.add(result) } void SendResults( int resultsToSend, Request *request ) { while ( resultsToSend > 0 ) { send(request.remove()) lock totalResultsCached --totalResultsCached unlock totalResultsCached --resultsToSend; } }

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  • Check if NSString exists in custom object in NSArray

    - by Paul Peelen
    I have an NSArray with Store objects. Each Store object has two NSString objects; StoreID and Name. I would like to check quickly if an ID exists in this NSArray with Store objects. Example: Store *s1 = [[Store alloc] init]; s1.name = @"Some Name"; s1.id = @"123ABC"; Store *s2 = [[Store alloc] init]; s2.name = @"Some Other Name"; s2.id = @"ABC123"; NSArray *array = [[NSArray alloc] initWithObjects:s1, s2, nil]; NSString *myIdOne = @"ABCDEF"; NSString *myIdTwo = @"123ABC"; BOOL myIdOneExists = ...? BOOL myIdTwoExists = ...? Its the ...? I need to figure out. I know I can do this using a for loop and break when found... but this seems to me like an nasty approach since the NSArray could contain thousands of objects,... theoretically. So I would like to know about a better solution.

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  • how to create an object using self?

    - by Nick
    I thought I understood the use of self while referring to anything in the current class. After encountering this warning and subsequent run failure, I have googled many variants of "define self" or "usage of self" and gotten nowhere. This problem is how to create an object without the warning, and understand why. #import <Cocoa/Cocoa.h> @interface Foo : NSObject { Foo *obj; } -(void)beta; @end #import "Foo.h" @implementation Foo -(void)beta{ obj = [self new]; // 'Foo' may not respond to '-new' } @end Note, if I substitute Foo for self, there's no problem. I thought the class name and self were equivalent, but obviously the compiler doesn't think so. Perhaps an explanation of what's wrong here will not only solve my problem but also enlighten my understanding of the usage of self. Are there any tutorials about proper usage of self? I couldn't find anything beyond something like "self is the receiver of the message," which I didn't help me at all.

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  • AS3---TypeError: Error #1009: Cannot access a property or method of a null object reference

    - by user571620
    I'm very new to flash and I really have no idea what I'm doing. Thank you in advance. its giving me that error after I click a button to go to another frame. After I get the error, some buttons do not go to its destination and instead it just does nothing. The error is as follows: TypeError: Error #1009: Cannot access a property or method of a null object reference. at wmhssports_fla::MainTimeline/frame39() Here is the code for frame 39: stop(); winter_btn.addEventListener(MouseEvent.CLICK, buttonClick1); function buttonClick1(event:MouseEvent):void{ gotoAndPlay(39); }; spring_btn_boys.addEventListener(MouseEvent.CLICK, buttonClick10); function buttonClick10(event:MouseEvent):void{ gotoAndPlay(114); }; fall_btn_boys.addEventListener(MouseEvent.CLICK, buttonClick11); function buttonClick11(event:MouseEvent):void{ gotoAndPlay(135); }; Edit: I could email the file to someone, if they could look at it for me? Its REALLY sketchy due to my inexperience with flash, but then again its not that big of a clip. email me at: [email protected]

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  • Showing a MKAnnotation for custom object

    - by Chamanhm
    I have a list of objects and each of those has a title, name, description, latitude, longitude and address. Is it possible to show this objects as MKAnnotations? I've been stuck with this for hours now. When I tried to make the objects have a CLLocationCoordinate2D I kept getting the error about latitude or longitude not being assignable. #import <Foundation/Foundation.h> #import <MapKit/MapKit.h> @interface Oficina : NSObject <MKMapViewDelegate> @property (nonatomic, readwrite) CLLocationCoordinate2D oficinaCoordinate; @property (nonatomic, strong) NSString *oficinaCiudad; @property (nonatomic, strong) NSString *oficinaEstado; @property (nonatomic, strong) NSString *oficinaTitulo; @property (nonatomic, strong) NSString *oficinaTelefono; @property (nonatomic, strong) NSString *oficinaLatitud; @property (nonatomic, strong) NSString *oficinaLongitud; @property (nonatomic, strong) NSString *oficinaID; @property (nonatomic, strong) NSString *oficinaDireccion; @property (nonatomic, strong) NSString *oficinaHorario; @property (nonatomic, strong) NSString *oficinaTipoDeOficina; @property (nonatomic, strong) NSString *oficinaServicios; @property (nonatomic, strong) NSString *oficinaTipoDeModulo; @end So after consuming an internet service I get around 70 of these objects. Now I want to be able to turn each of those into a map annotation. This is one of the ways I've tried to assign the latitude but I get the error "Expression not assignable".. currentOffice.oficinaCoordinate.latitude = [parseCharacters floatValue]; Where currentOffice is an instance of my custom object.

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  • Forcing size of a complex Flash object.

    - by John
    As I've found recently, setting width/height properties on a Sprite only forces the Sprite to fit the given dimensions by scaling the actual size, which is calculated by Flash based on the rendered content. This leaves me confused. If I have a custom Sprite subclass which draws using Graphics, how can I do layout before an initial render - the size will be zero until it is first drawn? For a more complex issue, let's say I have a 2D game world with objects spread over a wide area with world coordinates from (0,0) to (5000,5000), where each object has a size of maybe up to 100x100. I want to have a Flash component which is the "game window", and has a fixed size like 400x300, rendering part of the game world. So how do I force the game window size to 400x300 pixels? I can draw a 400x300 rectangle to get the size correct but then if I draw any objects which are partly in-view, they can screw this up. Is the right approach to provide a custom setSize(w,h) method which is used rather than width & height setters? But even so, is there no way to make a Sprite force to the size I want? Do you really have to catch it every render and re-scale it?

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  • Placing and removing element on array trough object

    - by Chris
    Hello, Lets assume i have 2 methods 1 that places a element on the array and one that removes it. const int Max = 10; int[] table= new int[Max]; I would like to call it up like this: s1.Place(5); // 5 0 0 0 0 0 0 0 0 0 0 s1.Place(9); // 5 9 0 0 0 0 0 0 0 0 0 s1.Remove(9); // 5 0 0 0 0 0 0 0 0 0 0 I would only like to use : using system for this. The result i get right now when i run the program is s1 = "nameofprogram" "name of class object" Normally i should get 0 0 0 0 0 0 0 0 0 0 to begin with. Any ideas how i can exactly add or remove those elements on the array? public void Place(int g) { if (top == Max) { throw new Exception("Stack overflow..."); } else { table[top] = g; top++; } .... Best Regards.

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  • Nullable object must have a value. VB.NET

    - by Glenn05
    I need help. I'm having problem in my program. This is my code on my Business logic layer. Function Load_ItemDetails(ByVal ItemID As String) As Items Dim objItemEnt As New tblitem Dim objitem As New Items Try Using da = New DataAccess objItemEnt = da.Load_ItemDetails(ItemID) With objitem .ItemCode = objItemEnt.ItemCode .ItemName = objItemEnt.ItemName .Description = objItemEnt.Description .NameofType = objItemEnt.NameofType .TypeofPricing = objItemEnt.TypeofPricing .OnStock = objItemEnt.OnStock .ItemPrice = objItemEnt.ItemPrice .DateModified = objItemEnt.DateModified End With Return objitem End Using Catch ex As Exception Throw End Try End Function This code is for my data access layer. Public Function Load_ItemDetails(ByVal ItemCode As String) Dim objitem As New tblitem Try Using entItem = New DAL.systemdbEntities1 Dim qryUsers = From p In entItem.tblitems Where p.ItemCode = ItemCode Select p Dim luser As List(Of tblitem) = qryUsers.ToList If luser.Count > 0 Then Return luser.First Else Return objitem End If End Using Catch ex As Exception Throw End Try End Function` For my Presentation layer: Private Sub Load_Item_Detail(ByVal ItemCode As String) objItem = New Items Using objLogic = New LogicalLayer objItem = objLogic.Load_ItemDetails(ItemCode) With objItem Me.ItemCodetxt.Text = .ItemCode Me.ItemNametxt.Text = .ItemName Me.ItemDesctxt.Text = .Description Me.ItemTypetxt.Text = .NameofType Me.ItemPricetxt.Text = .TypeofPricing Me.ItemOnstocktxt.Text = CStr(.OnStock) Me.ItemPricetxt.Text = CStr(.ItemPrice) Me.TextBox1.Text = CStr(.DateModified) Me.ItemCodetxt.Tag = .ItemCode End With End Using End Sub` and after I run, I get this error Nullable object must have a value help me. I'm stuck. I don't know what to do guys. I new in n tier architecture.

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  • [Django] One single page to create a Parent object and its associated child objects

    - by ahmoo
    Hi all, This is my very first post on this awesome site, from which I have been finding answers to a handful of challenging questions. Kudos to the community! I am new to the Django world, so am hoping to find help from some Django experts here. Thanks in advance. Item model: class Item(models.Model): name = models.CharField(max_length=50) ItemImage model: class ItemImage(models.Model): image = models.ImageField(upload_to=get_unique_filename) item = models.ForeignKey(Item, related_name='images') As you can tell from the model definitions above, every Item object can have many ItemImage objects. My requirements are as followings: A single web page that allows users to create a new Item while uploading the images associated with the Item. The Item and the ItemImages objects should be created in the database all together, when the "Save" button on the page is clicked. I have created a variable in a custom config file, called NUMBER_OF_IMAGES_PER_ITEM. It is based on this variable that the system generates the number of image fields per item. Questions: What should the forms and the template be like? Can ModelForm be used to achieve the requirements? For the view function, what do I need to watch out other than making sure to save Item before ItemImage objects?

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  • Efficiently fill resultset in object model

    - by Zeeshan
    Hi, I have an object model whose structure is Dashboard  List of panels     List of containers       List of widgets If i get whole dashboard, with panels + containers + widgets, from Database then multiple I/O requires I want to get it in one I/O .For this i prepared a query which gives me this resultset. DASHBOARDID   PANELID  CONTAINERID  WIDGETID 13                          11                    5              2 13                          11                    5              3 13                          11                    6              4 13                          11                    6              5 13                          12                    7              6 13                          12                    7              7 13                          12                    8              8 13                          12                    8              9 Using list datastructure this model is able to be filled but it takes time i want to efficiently fill this resultset in above object model. is there nay way ?

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  • Setting default values for object properties in AS3

    - by Paul T
    I'm an actionscript newbie so please bear with me. Below is a function, and I am curious how to set default property values for objects that are being created in a loop. In the example below, these propeties are the same for each object created in the loop: titleTextField.selectable, titleTextField.wordWrap, titleTextField.x If you pull these properties out of the loop, they are null because the TextField objects have not been created, but it seems silly to have to set them each time. What is the correct way to do this. Thanks! var titleTextFormat:TextFormat = new TextFormat(); titleTextFormat.size = 10; titleTextFormat.font = "Arial"; titleTextFormat.color = 0xfff200; for (var i=0; i<arrThumbPicList.length; i++) { var yPos = 55 * i var titleTextField:TextField = new TextField(); titleTextField.selectable = false; titleTextField.wordWrap = true; titleTextField.text = arrThumbTitles[i]; titleTextField.x = 106; titleTextField.y = 331 + yPos; container.addChild(titleTextField); titleTextField.setTextFormat(titleTextFormat); }

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  • C++11 decltype requires instantiated object

    - by snipes83
    I was experimenting a little with the C++11 standard and came up with this problem: In C++11 you can use auto and decltype to automatically get return type for a function as, for example the begin() and end() functions below: #include <vector> template <typename T> class Container { private: std::vector<T> v; public: auto begin() -> decltype(v.begin()) { return v.begin(); }; auto end() -> decltype(v.end()) { return v.end(); }; }; My problem here is that I have to declare the private vector<T> v before the public declarations which is against my coding style. I would like to declare all my private members after my public members. You have to declare the vector before the function declaration because the expression in decltype is a call to vector member function begin() and requires an instance of the object. Is there a way around this?

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  • Call to a member function find() on a non-object simpleHTMLDOM PHP

    - by wandersolo
    I am trying to read a link from one page, print the url, go to that page, and read the link on the next page in the same location, print the url, go to that page (and so on...) All I'm doing is reading the url and passing it as an argument to the get_links() method until there are no more links. This is my code but it throws a Fatal error: Call to a member function find() on a non-object. Anyone know what's wrong? <?php $mainPage = 'https://www.bu.edu/link/bin/uiscgi_studentlink.pl/1346752597?ModuleName=univschr.pl&SearchOptionDesc=Class+Subject&SearchOptionCd=C&KeySem=20133&ViewSem=Fall+2012&Subject=&MtgDay=&MtgTime='; get_links($mainPage); function get_links($url) { $data = new simple_html_dom(); $data = file_get_html($url); $nodes = $data->find("input[type=hidden]"); $fURL=$data->find("/html/body/form"); $firstPart = $fURL[0]->action . '<br>'; foreach ($nodes as $node) { $val = $node->value; $name = $node->name; $name . '<br />'; $val . "<br />"; $str1 = $str1. "&" . $name . "=" . $val; } $fixStr1 = str_replace('&College', '?College', $str1); $fixStr2 = str_replace('Fall 2012', 'Fall+2012', $fixStr1); $fixStr3 = str_replace('Class Subject', 'Class+Subject', $fixStr2); $fixStr4 = $firstPart . $fixStr3; echo $nextPageURL = chop($fixStr4); get_links($nextPageURL); } ?>

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  • How to Link VS2010 Database Project and LINQ to SQL

    - by Jason
    As I am working with the new database projects in VS2010, and as I am learning LINQ to SQL, I am curious as to the best way to link the two groups of information so that when I update one, the other updates along with it. From my research here at SO, as well as in Google, it appears the general rule of thumb is: "Build the database, and then create your LINQ to SQL classes." Of course, if I make a change in my database, the LINQ to SQL doesn't update automatically and I have to do it by hand. This is fairly simple right now as my database is small, but I am curious if there is an easier way for this to happen. In addition, the LINQ to SQL tool is pretty nice. The ability to create tables, add associations, and even create inheritance is very simple. As my second question, I am curious as to whether or not VS2010 can work the other way - I design the database in the DBLM file and then link it back to my database project. I appreciate any help with either of these two questions. I'm really interested in making this as easy as possible to reduce errors during development and improve the speed at which changes can be made.

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  • ReSharper - Possible Null Assignment when using Microsoft.Contracts

    - by HVS
    Is there any way to indicate to ReSharper that a null reference won't occur because of Design-by-Contract Requires checking? For example, the following code will raise the warning (Possible 'null' assignment to entity marked with 'NotNull' attribute) in ReSharper on lines 7 and 8: private Dictionary<string, string> _Lookup = new Dictionary<string, string>(); public void Foo(string s) { Contract.Requires(!String.IsNullOrEmpty(s)); if (_Lookup.ContainsKey(s)) _Lookup.Remove(s); } What is really odd is that if you remove the Contract.Requires(...) line, the ReSharper message goes away. Update I found the solution through ExternalAnnotations which was also mentioned by Mike below. Here's an example of how to do it for a function in Microsoft.Contracts: Create a directory called Microsoft.Contracts under the ExternalAnnotations ReSharper directory. Next, Create a file called Microsoft.Contracts.xml and populate like so: <assembly name="Microsoft.Contracts"> <member name="M:System.Diagnostics.Contracts.Contract.Requires(System.Boolean)"> <attribute ctor="M:JetBrains.Annotations.AssertionMethodAttribute.#ctor"/> <parameter name="condition"> <attribute ctor="M:JetBrains.Annotations.AssertionConditionAttribute.#ctor(JetBrains.Annotations.AssertionConditionType)"> <argument>0</argument> </attribute> </parameter> </member> </assembly> Restart Visual Studio, and the message goes away!

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  • Legit? Two foreign keys referencing the same primary key.

    - by Ryan
    Hi All, I'm a web developer and have recently started a project with a company. Currently, I'm working with their DBA on getting the schema laid out for the site, and we've come to a disagreement regarding the design on a couple tables, and I'd like some opinions on the matter. Basically, we are working on a site that will implement a "friends" network. All users of the site will be contained in a table tblUsers with (PersonID int identity PK, etc). What I am wanting to do is to create a second table, tblNetwork, that will hold all of the relationships between users, with (NetworkID int identity PK, Owners_PersonID int FK, Friends_PersonID int FK, etc). Or conversely, remove the NetworkID, and have both the Owners_PersonID and Friends_PersonID shared as the Primary key. This is where the DBA has his problem. Saying that "he would only implement this kind of architecture in a data warehousing schema, and not for a website, and this is just another example of web developers trying to take the easy way out." Now obviously, his remark was a bit inflammatory, and that have helped motivate me to find an suitable answer, but more so, I'd just like to know how to do it right. I've been developing databases and programming for over 10 years, have worked with some top-notch minds, and have never heard this kind of argument. What the DBA is wanting to do is instead of storing both the Owners_PersonId and Friends_PersonId in the same table, is to create a third table tblFriends to store the Friends_PersonId, and have the tblNetwork have (NetworkID int identity PK, Owner_PersonID int FK, FriendsID int FK(from TBLFriends)). All that tblFriends would house would be (FriendsID int identity PK, Friends_PersonID(related back to Persons)). To me, creating the third table is just excessive in nature, and does nothing but create an alias for the Friends_PersonID, and cause me to have to add (what I view as unneeded) joins to all my queries, not to mention the extra cycles that will be necessary to perform the join on every query. Thanks for reading, appreciate comments. Ryan

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  • Invoice & Invoice lines: How do you store customer address information?

    - by elviejo
    Hi I'm developing an invoicing application. So the general idea is to have two tables: Invoice (ID, Date, CustomerAddress, CustomerState, CustomerCountry, VAT, Total); InvoiceLine (Invoice_ID, ID, Concept, Units, PricePerUnit, Total); As you can see this basic design leads to a lot of repetiton of records where the client will have the same addrres, state and country. So the alternative is to have an address table and then make a relationship Address<-Invoice. However I think that an invoice is immutable document and should be stored just the way it was first made. Sometimes customers change their addresses, or states and if it was coming from an Address catalog that will change all the previously made invoices. So What is your experience? How is the customer address stored in an invoice? In the Invoice table? an Address Table? or something else? Can you provide pointers to a book, article or document where this is discussed in further detail?

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  • Database structure - is mySQL the right choice?

    - by Industrial
    Hi everyone, We are currently planning the database structure of a quite complex e-commerce web app that has flexibility as it's main cornerstone. Our app features a large amount of data (products) and we have run into a slight headache trying to keep performance high without compromizing normalization rules in the database, or leaving our highly beloved flexibility concept behind when integrating product options (also widely known as product attributes or parameters). Based on various references and sources available, we have made up lists on pros and cons of all major and well known database patterns to solve this. After comparing these, we have come up with two final alternatives: EAV (Entity-attribute-value model) : Pros: Database is used for all sorting. Cons: All related queries will include a number of joins between multiple tables in order to complete the collection of data. SLOB (Serialized LOB, also known as Facade?) : Pros: Very flexible. Keeping the number of necessary joins low compared to a EAV design pattern. Easy to update/add/remove data from each product. Cons: All sorting will be done by the application instead of the database. Will use lots of performance (memory?) when big datasets is processed by a large number of users. Our main questions: Which pattern/structure would you use, or maybe even a different solution? Is there better databases besides mySQL available nowadays to accomplish what we want? Thanks a lot! Reference: http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters

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  • DDD: Aggregate Roots

    - by Mosh
    Hello, I need help with finding my aggregate root and boundary. I have 3 Entities: Plan, PlannedRole and PlannedTraining. Each Plan can include many PlannedRoles and PlannedTrainings. Solution 1: At first I thought Plan is the aggregate root because PlannedRole and PlannedTraining do not make sense out of the context of a Plan. They are always within a plan. Also, we have a business rule that says each Plan can have a maximum of 3 PlannedRoles and 5 PlannedTrainings. So I thought by nominating the Plan as the aggregate root, I can enforce this invariant. However, we have a Search page where the user searches for Plans. The results shows a few properties of the Plan itself (and none of its PlannedRoles or PlannedTrainings). I thought if I have to load the entire aggregate, it would have a lot of overhead. There are nearly 3000 plans and each may have a few children. Loading all these objects together and then ignoring PlannedRoles and PlannedTrainings in the search page doesn't make sense to me. Solution 2: I just realized the user wants 2 more search pages where they can search for Planned Roles or Planned Trainings. That made me realize they are trying to access these objects independently and "out of" the context of Plan. So I thought I was wrong about my initial design and that is how I came up with this solution. So, I thought to have 3 aggregates here, 1 for each Entity. This approach enables me to search for each Entity independently and also resolves the performance issue in solution 1. However, using this approach I cannot enforce the invariant I mentioned earlier. There is also another invariant that states a Plan can be changed only if it is of a certain status. So, I shouldn't be able to add any PlannedRoles or PlannedTrainings to a Plan that is not in that status. Again, I can't enforce this invariant with the second approach. Any advice would be greatly appreciated. Cheers, Mosh

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  • .NET Membership with Repository Pattern

    - by Zac
    My team is in the process of designing a domain model which will hide various different data sources behind a unified repository abstraction. One of the main drivers for this approach is the very high probability that these data sources will undergo significant change in the near future and we don't want to be re-writing business logic when this happens. One data source will be our membership database which was originally implemented using the default ASP.Net Membership Provider. The membership provider is tied to the System.Web.Security namespace but we have a design guideline requiring that our domain model layer is not dependent upon System.Web (or any other implementation/environment dependency) as it will be consumed in different environments - nor do we want our websites directly communicating with databases. I am considering what would be a good approach to reconciling the MembershipProvider approach with our abstracted n-tier architecture. My initial feeling is that we could create a "DomainMembershipProvider" which interacts with the domain model and then implement objects in the model which deal with the repository and handle validation/business logic. The repository would then implement data access using our (as-yet undecided) ORM/data access tool. Are there are any glaring holes in this approach - I haven't worked closely with the MembershipProvider class so may well be missing something. Alternatively, is there an approach that you think will better serve the requirements I described above? Thanks in advance for your thoughts and advice. Regards, Zac

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  • structured vs. unstructured data in db

    - by Igor
    the question is one of design. i'm gathering a big chunk of performance data with lots of key-value pairs. pretty much everything in /proc/cpuinfo, /proc/meminfo/, /proc/loadavg, plus a bunch of other stuff, from several hundred hosts. right now, i just need to display the latest chunk of data in my UI. i will probably end up doing some analysis of the data gathered to figure out performance problems down the road, but this is a new application so i'm not sure what exactly i'm looking for performance-wise just yet. i could structure the data in the db -- have a column for each key i'm gathering. the table would end up being O(100) columns wide, it would be a pain to put into the db, i would have to add new columns if i start gathering a new stat. but it would be easy to sort/analyze the data just using SQL. or i could just dump my unstructured data blob into the table. maybe three columns -- host id, timestamp, and a serialized version of my array, probably using JSON in a TEXT field. which should I do? am i going to be sorry if i go with the unstructured approach? when doing analysis, should i just convert the fields i'm interested in and create a new, more structured table? what are the trade-offs i'm missing here?

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  • Database migration pattern for Java?

    - by Eno
    Im working on some database migration code in Java. Im also using a factory pattern so I can use different kinds of databases. And each kind of database im using implements a common interface. What I would like to do is have a migration check that is internal to the class and runs some database schema update code automatically. The actual update is pretty straight forward (I check schema version in a table and compare against a constant in my app to decide whether to migrate or not and between which versions of schema). To make this automatic I was thinking the test should live inside (or be called from) the constructor. OK, fair enough, that's simple enough. My problem is that I dont want the test to run every single time I instantiate a database object (it runs a query so having it run on every construction is not efficient). So maybe this should be a class static method? I guess my question is, what is a good design pattern for this type of problem? There ought to be a clean way to ensure the migration test runs only once OR is super-efficient.

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