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  • Avoiding null point exception in el in JSF

    - by Buddhika Ariyaratne
    I am developing a JSF application with JPA(EclipseLink 2.0) and Primefaces. I want to know is there any way to avoid null point exception when el calls a property of a null object. I have described the situation. I have Bill class. There may be no or more BillItem objects with a Bill objects. Each BillItem object have Objects like Make, Country, Manufacturer, etc objects. I am displaying several properties of a bill within a single JSF file like this. "#{billControlled.bill.billItem.modal.name}" But if a bill is not selected, or when there are no bill items for a selected bill, the properties accessing in the el are null. I can avoid this by creating new objects for every bill, for example, new make for a new bill item, etc or by creating new properties in the controller itself for all the properties. But that is a very long way and feel like rudimentory. Is there any good practice to avoid this null point exception in el in JSF?

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  • Do you know of a free .Net component for visual flow model graph design and editing?

    - by Ivan
    An app (C#4, WinForms, Entity Framework, SQL Server 2008) of mine maintains a graph of interconnected objects, each having some simple member fields and a set of many directed (in and out) one-to-one links to other objects. I'd like to offer a user an ability to view and edit this graph visually some way, creating and removing connections, modifying objects attributes values and introducing/dropping objects. I suppose there has to be a framework (at list a primitive kind of) for this as visual model design tools are pretty common to meet. Do you know one?

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  • Ret Failure with SDL using FASM on Win32

    - by Jon Purdy
    I'm using SDL with FASM, and have code that's minimally like the following: format ELF extrn _SDL_Init extrn _SDL_SetVideoMode extrn _SDL_Quit extrn _exit SDL_INIT_VIDEO equ 0x00000020 section '.text' public _SDL_main _SDL_main: ccall _SDL_Init, SDL_INIT_VIDEO ccall _SDL_SetVideoMode, 640, 480, 32, 0 ccall _SDL_Quit ccall _exit, 0 ; Success, or ret ; failure. With the following quick-and-dirty makefile: SOURCES = main.asm OBJECTS = main.o TARGET = SDLASM.exe FASM = C:\fasm\fasm.exe release : $(OBJECTS) ld $(OBJECTS) -LC:/SDL/lib/ -lSDLmain -lSDL -LC:/MinGW/lib/ -lmingw32 -lcrtdll -o $(TARGET) --subsystem windows cleanrelease : del $(OBJECTS) %.o : %.asm $(FASM) $< $@ Using exit() (or Windows' ExitProcess()) seems to be the only way to get this program to exit cleanly, even though I feel like I should be able to use retn/retf. When I just ret without calling exit(), the application does not terminate and needs to be killed. Could anyone shed some light on this? It only happens when I make the call to SDL_SetVideoMode().

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  • Deleting entity with child relationships using .Net Entity Framework problem

    - by Am
    My God, EF is so frustrating. I can't seem to be able to get my head around what I need to do so I can delete an object. I seem to be able to remove the object but not the related child objects. Can anyone tell me what is the rule of thumb when you want to delete all related child objects of a given object? I've tried loading all related objects like this: if (!object.childobjects.IsLoaded) object.childobjects.Load(); but once I do the following I get errors related to the relationships: modelcontext.DeleteObject(object); modelcontext.SaveChanges(); Why can't I just load the object using modelcontext.GetObjectByKey and remove it along with its child objects? My other question is can I delete an object using Entity command like so? DELETE e from objectset as e where e.id = 12 I've tried few variations and all of them throw exceptions.

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  • Inference engine to calculate matching set according to internal rules

    - by Zecrates
    I have a set of objects with attributes and a bunch of rules that, when applied to the set of objects, provides a subset of those objects. To make this easier to understand I'll provide a concrete example. My objects are persons and each has three attributes: country of origin, gender and age group (all attributes are discrete). I have a bunch of rules, like "all males from the US", which correspond with subsets of this larger set of objects. I'm looking for either an existing Java "inference engine" or something similar, which will be able to map from the rules to a subset of persons, or advice on how to go about creating my own. I have read up on rule engines, but that term seems to be exclusively used for expert systems that externalize the business rules, and usually doesn't include any advanced form of inferencing. Here are some examples of the more complex scenarios I have to deal with: I need the conjunction of rules. So when presented with both "include all males" and "exclude all US persons in the 10 - 20 age group," I'm only interested in the males outside of the US, and the males within the US that are outside the 10 - 20 age group. Rules may have different priorities (explicitly defined). So a rule saying "exclude all males" will override a rule saying "include all US males." Rules may be conflicting. So I could have both an "include all males" and an "exclude all males" in which case the priorities will have to settle the issue. Rules are symmetric. So "include all males" is equivalent to "exclude all females." Rules (or rather subsets) may have meta rules (explicitly defined) associated with them. These meta rules will have to be applied in any case that the original rule is applied, or if the subset is reached via inferencing. So if a meta rule of "exclude the US" is attached to the rule "include all males", and I provide the engine with the rule "exclude all females," it should be able to inference that the "exclude all females" subset is equivalent to the "include all males" subset and as such apply the "exclude the US" rule additionally. I can in all likelihood live without item 5, but I do need all the other properties mentioned. Both my rules and objects are stored in a database and may be updated at any stage, so I'd need to instantiate the 'inference engine' when needed and destroy it afterward.

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  • How to write async background workers that work on WPF flowdocument

    - by iBe
    I'm trying to write a background worker that processes a flowdocument. I can't access the properties of flowdocument objects because of the thread verification. I tried to serialize the document and loaded it on the worker thread which actually solved the thread verfication issue. However, once the processing is complete I also need to use things like TextPointer objects. Those objects now point to a objects in the copy not the original. Can anyone suggest the best way to approach such background processing in WPF?

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  • Hierarchy / Flyweight / Instancing Problem in Python

    - by Dan
    Here is the problem I am trying to solve, (I have simplified the actual problem, but this should give you all the relevant information). I have a hierarchy like so: 1.A 1.B 1.C 2.A 3.D 4.B 5.F (This is hard to illustrate - each number is the parent, each letter is the child). Creating an instance of the 'letter' objects is expensive (IO, database costs, etc), so should only be done once. The hierarchy needs to be easy to navigate. Children in the hierarchy need to have just one parent. Modifying the contents of the letter objects should be possible directly from the objects in the hierarchy. There needs to be a central store containing all of the 'letter' objects (and only those in the hierarchy). 'letter' and 'number' objects need to be possible to create from a constructor (such as Letter(**kwargs) ). It is perfectably acceptable to expect that when a letter changes from the hierarchy, all other letters will respect the same change. Hope this isn't too abstract to illustrate the problem. What would be the best way of solving this? (Then I'll post my solution) Here's an example script: one = Number('one') a = Letter('a') one.addChild(a) two = Number('two') a = Letter('a') two.addChild(a) for child in one: child.method1() for child in two: print '%s' % child.method2()

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  • Ajax data two-way data binding strategies?

    - by morgancodes
    I'd like to 1) Draw create form fields and populate them with data from javascript objects 2) Update those backing objects whenever the value of the form field changes Number 1 is easy. I have a few js template systems I've been using that work quite nicely. Number 2 may require a bit of thought. A quick google search on "ajax data binding" turned up a few systems which seem basically one-way. They're designed to update a UI based on backing js objects, but don't seem to address the question of how to update those backing objects when changes are made to the UI. Can anyone recommend any libraries which will do this for me? It's something I can write myself without too much trouble, but if this question has already been thought through, I'd rather not duplicate the work.

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  • Two different definitions of database schema

    - by AspOnMyNet
    a) I found two definitions of schema: FIRST - A set of information that describes a table is known as a schema, and schemas are used to describe specific tables within a database, as well as entire databases (and the relationship between tables in them, if any). SECOND - A database schema is a way to logically group objects such as tables, views, stored procedures etc. Think of a schema as a container of objects. I assume the two descriptions describe entirely different concepts, which just happen to use the same name? b) A database schema is a way to logically group objects such as tables, views, stored procedures etc. Think of a schema as a container of objects. If I understand the above definition correctly, then database schema is similar to a namespace, only difference being that we can assign access permissions to database schema, while same can’t be done with namespaces? thanx

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  • How would the 'Model' in a Rails-type webapp be implemented in a functional programming langauge?

    - by ceptorial
    In MVC web development frameworks such as Ruby on Rails, Django, and CakePHP, HTTP requests are routed to controllers, which fetch objects which are usually persisted to a backend database store. These objects represent things like users, blog posts, etc., and often contain logic within their methods for permissions, fetching and/or mutating other objects, validation, etc. These frameworks are all very much object oriented. I've been reading up recently on functional programming and it seems to tout tremendous benefits such as testability, conciseness, modularity, etc. However most of the examples I've seen for functional programming implement trivial functionality like quicksort or the fibonnacci sequence, not complex webapps. I've looked at a few 'functional' web frameworks, and they all seem to implement the view and controller just fine, but largely skip over the whole 'model' and 'persistence' part. (I'm talking more about frameworks like Compojure which are supposed to be purely functional, versus something Lift which conveniently seems to use the OO part of Scala for the model -- but correct me if I'm wrong here.) I haven't seen a good explanation of how functional programming can be used to provide the metaphor that OO programming provides, i.e. tables map to objects, and objects can have methods which provide powerful, encapsulated logic such as permissioning and validation. Also the whole concept of using SQL queries to persist data seems to violate the whole 'side effects' concept. Could someone provide an explanation of how the 'model' layer would be implemented in a functionally programmed web framework?

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  • Looking for an elegant way to store one-to-many relationship in coredata when order is important

    - by Eric Schweichler
    I've been trying to come up with a way to solve my problem, but every solution I can think of is messy and makes me want to retch. I have a one-to-many relationship, consisting of a Team object that can have many Member objects. When I built my data model using Xcode, I was given the default NSSet in which to store the member objects, Unfortunately Sets are not ordered and I need to preserve the order of the Member objects and I need to know if there are empty spaces between Members. I thought of Using an NSArray in place of the NSSet and creating a dummy Member object in my data store that I could use to mark vacant a spot between to Member objects, but that solution really feels like too much of a hack to me. Since I'll always have to filter out this dummy Member from any queries. An NSDictionary would be perfect as I could store the Member object references and their positions as Object-Key pairs, (taking care of both order and vacancies) but apparently CoreData does not support NSDictionary. Has anyone had a similar need, and devised a simple solution?

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  • NSUndoManager, Core Data and selective undo/redo

    - by Combat
    I'm working on a core data application that has a rather large hierarchy of managed objects similar to a tree. When a base object is created, it creates a few child objects which in turn create their own child objects and so on. Each of these child objects may gather information using NSURLConnections. Now, I'd like to support undo/redo with the undoManager in the managedObjectContext. The problem is, if a user creates a base object, then tries to undo that action, the base object is not removed. Instead, one or more of the child objects may be removed. Obviously this type of action is unpredictable and unwanted. So I tried disabling undo registration by default. I did this by calling disableUndoRegistration: before anything is modified in the managedObjectContext. Then, enabling undo registration before base operations such as creating a base object the again re-disabling registrations afterwords. Now when i try to undo, I get this error: undo: NSUndoManager 0x1026428b0 is in invalid state, undo was called with too many nested undo groups Thoughts?

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  • How to skip "Loose Object" popup when running 'git gui'

    - by Michael Donohue
    When I run 'git gui' I get a popup that says This repository currently has approximately 1500 loose objects. It then suggests compressing the database. I've done this before, and it reduces the loose objects to about 250, but that doesn't suppress the popup. Compressing again doesn't change the number of loose objects. Our current workflow requires significant use of 'rebase' as we are transitioning from Perforce, and Perforce is still the canonical SCM. Once Git is the canonical SCM, we will do regular merges, and the loose objects problem should be greatly mitigated. In the mean time, I'd really like to make this 'helpful' popup go away.

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  • ORM solutions (JPA; Hibernate) vs. JDBC

    - by Grasper
    I need to be able to insert/update objects at a consistent rate of at least 8000 objects every 5 seconds in an in-memory HSQL database. I have done some comparison performance testing between Spring/Hibernate/JPA and pure JDBC. I have found a significant difference in performance using HSQL.. With Spring/Hib/JPA, I can insert 3000-4000 of my 1.5 KB objects (with a One-Many and a Many-Many relationship) in 5 seconds, while with direct JDBC calls I can insert 10,000-12,000 of those same objects. I cannot figure out why there is such a huge discrepancy. I have tweaked the Spring/Hib/JPA settings a lot trying to get close in performance without luck. I want to use Spring/Hib/JPA for future purposes, expandability, and because the foreign key relationships (one-many and many-many) are difficult to maintain by hand; but the performance requirements seem to point towards using pure JDBC. Any ideas of why there would be such a huge discrepancy?

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  • Java object caching, which is faster, reading from a file or from a remote machine?

    - by Kumar225
    I am at a point where I need to take the decision on what to do when caching of objects reaches the configured threshold. Should I store the objects in a indexed file (like provided by JCS) and read them from the file (file IO) when required or have the object stored in a distributed cache (network, serialization, deserialization) We are using Solaris as OS. ============================ Adding some more information. I have this question so as to determine if I can switch to distributed caching. The remote server which will have cache will have more memory and better disk and this remote server will only be used for caching. One of the problems we cannot increase the locally cached objects is , it stores the cached objects in JVM heap which has limited memory(using 32bit JVM). ======================================================================== Thanks, we finally ended up choosing Coherence as our Cache product. This provides many cache configuration topologies, in process vs remote vs disk ..etc.

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  • Associate "Code/Properties/Stuff" with Fields in C# without reflection. I am too indoctrinated by J

    - by AlexH
    I am building a library to automatically create forms for Objects in the project that I am working on. The codebase is in C#, and essentially we have a HUGE number of different objects to store information about different things. If I send these objects to the client side as JSON, it is easy enough to programatically inspect them to generate a form for all of the properties. The problem is that I want to be able to create a simple way of enforcing permissions and doing validation on the client side. It needs to be done on a field by field level. In javascript I would do this by creating a parallel object structure, which had some sort of { permissions : "someLevel", validator : someFunction } object at the nodes. With empty nodes implying free permissions and universal validation. This would let me simply iterate over the new object and the permissions object, run the check, and deal with the result. Because I am overfamilar with the hammer that is javascript, this is really the only way that I can see to deal with this problem. My first implementation thus uses reflection to let me treat objects as dictionaries, that can be programatically iterated over, and then I just have dictionaries of dictionaries of PermissionRule objects which can be compared with. Very javascripty. Very awkward. Is there some better way that I can do this? Essentially a way to associate a data set with each property, and then iterate over those properties. Or else am I Doing It Wrong?

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  • Coloring NSTableView Text per row

    - by Tristan
    I have a NSTableView that is displaying an array of objects I have. For each of these objects (rows) I would like to change the color of the text displayed depending on the results of a function I run on each object; So for example all the object in the table that exist in another list (or some other requirement) I want to display them in green text, and objects that don't exist display in red. How would I go about doing this?

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  • Class type while deserialization in c++

    - by Rushi
    I am developing game editor in c++.I have implemented reflection mechanism using DiaSDK.Now I want to store state of the objects(Like Camera,Lights,Static mesh) in some level file via serialization. And later on able to retrieve their state via deserialization.Serializing objects is not a problem for me.But while deserializing objects how do I know class type?so that i can create object of that particular type.

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  • Turn Function or Stored Procedure Result into "live" Result for LINQ

    - by Alex
    Is it possible to turn result sets obtained in LINQ through a stored procedure or function call into a "live" set of objects of which I can retrieve Foreign Key related objects? If, for example, my stored procedure returns a set of rows (= LINQ objects) of type "Contact", then I can't seem to obtain Contact.BillingAddress (which is related by Foreign Key). Any idea how to make this work?

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  • Django Initial for a ManyToMany Field

    - by gramware
    I have a form that edits an instance of my model. I would like to use the form to pass all the values as hidden with an inital values of username defaulting to the logged in user so that it becomes a subscribe form. The problem is that the normal initial={'field':value} doesn't seem to work for manytomany fields. how do i go about it? my views.py @login_required def event_view(request,eventID): user = UserProfile.objects.get(pk=request.session['_auth_user_id']) event = events.objects.get(eventID = eventID) if request.method == 'POST': form = eventsSusbcribeForm( request.POST,instance=event) if form.is_valid(): form.save() return HttpResponseRedirect('/events/') else: form = eventsSusbcribeForm(instance=event) return render_to_response('event_view.html', {'user':user,'event':event, 'form':form},context_instance = RequestContext( request )) my forms.py class eventsSusbcribeForm(forms.ModelForm): eventposter = forms.ModelChoiceField(queryset=UserProfile.objects.all(), widget=forms.HiddenInput()) details = forms.CharField(widget=forms.Textarea(attrs={'cols':'50', 'rows':'5'}),label='Enter Event Description here') date = forms.DateField(widget=SelectDateWidget()) class Meta: model = events exclude = ('deleted') def __init__(self, *args, **kwargs): super(eventsSusbcribeForm, self).__init__(*args, **kwargs) self.fields['username'].initial = (user.id for user in UserProfile.objects.filter())

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  • What is the best solution to do Reporting on Object data for .NET ?

    - by Peter Fox
    Hi, Our projects are using objects as the data source to reports. Our business layer is returning single objects or IEnumerable. Our reports (quite complex) need to display value-type properties of the object, and its related objects. Typical case would be, from a List, display a master report with category data, then a subreport with data for each Product inside each Category, then a subreport for each Part of each Product, and so on. Reporting from the database is not an option for us. We have tried so far - Reporting Services : works but have to mess around with the XML definition of the report to define the datasource classes, very hard to work with if you use an object datasource, architecturally not too clean - Telerik Reports : quite nice (esp., nice architecture) but seems to have problems with complex reports (master/sub), does not give great paging control, rumored to have performance/crash problems (immature product). Does anyone know a good reporting solution that can be integrated in an ASP.NET application and works well with objects as datasources ?

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  • How to keep your unit test Arrange step simple and still guarantee DDD invariants ?

    - by ian31
    DDD recommends that the domain objects should be in a valid state at any time. Aggregate roots are responsible for guaranteeing the invariants and Factories for assembling objects with all the required parts so that they are initialized in a valid state. However this seems to complicate the task of creating simple, isolated unit tests a lot. Let's assume we have a BookRepository that contains Books. A Book has : an Author a Category a list of Bookstores you can find the book in These are required attributes : a book has to have an author, a category and at least a book store you can buy the book from. There's likely to be a BookFactory since it is quite a complex object, and the Factory will initialize the Book with at least all the mentioned attributes. Now we want to unit test a method of the BookRepository that returns all the Books. To test if the method returns the books, we have to set up a test context (the Arrange step in AAA terms) where some Books are already in the Repository. If the only tool at our disposal to create Book objects is the Factory, the unit test now also uses and is dependent on the Factory and inderectly on Category, Author and Store since we need those objects to build up a Book and then place it in the test context. Would you consider this is a dependency in the same way that in a Service unit test we would be dependent on, say, a Repository that the Service would call ? How would you solve the problem of having to re-create a whole cluster of objects in order to be able to test a simple thing ? How would you break that dependency and get rid of all these attributes we don't need in our test ? By using mocks or stubs ? If you mock up things a Repository contains, what kind of mock/stubs would you use as opposed to when you mock up something the object under test talks to or consumes ?

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  • How to keep your unit tests simple and isolated and still guarantee DDD invariants ?

    - by ian31
    DDD recommends that the domain objects should be in a valid state at any time. Aggregate roots are responsible for guaranteeing the invariants and Factories for assembling objects with all the required parts so that they are initialized in a valid state. However this seems to complicate the task of creating simple, isolated unit tests a lot. Let's assume we have a BookRepository that contains Books. A Book has : an Author a Category a list of Bookstores you can find the book in These are required attributes : a book has to have an author, a category and at least a book store you can buy the book from. There's likely to be a BookFactory since it is quite a complex object, and the Factory will initialize the Book with at least all the mentioned attributes. Now we want to unit test a method of the BookRepository that returns all the Books. To test if the method returns the books, we have to set up a test context (the Arrange step in AAA terms) where some Books are already in the Repository. If the only tool at our disposal to create Book objects is the Factory, the unit test now also uses and is dependent on the Factory and inderectly on Category, Author and Store since we need those objects to build up a Book and then place it in the test context. Would you consider this is a dependency in the same way that in a Service unit test we would be dependent on, say, a Repository that the Service would call ? How would you solve the problem of having to re-create a whole cluster of objects in order to be able to test a simple thing ? How would you break that dependency and get rid of all these attributes we don't need in our test ? By using mocks or stubs ? If you mock up things a Repository contains, what kind of mock/stubs would you use as opposed to when you mock up something the object under test talks to or consumes ?

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  • How to create a custom ADO Multi Demensional Catalog with no database

    - by Alan Clark
    Does anyone know of an example of how to dynamically define and build ADO MD (ActiveX Data Objects Multidimensional) catalogs and cube definitions with a set of data other than a database? Background: we have a huge amount of data in our application that we export to a database and then query using the usual SQL joins, groups, sums etc to produce reports. The data in the application is originally in objects and arrays. The problem is the amount of data is so large the export can take 2 hours. So I am trying to figure out a good way of querying the objects in memory, either by a custom OLAP algorithm or library, or ADO MD. But I haven't been able to find an example of using ADO MD without a database behind it. We are using Delphi 2010 so would use ADO ActiveX but I imagine the ADO.NET MD is similar. I realize that if the application data was already stored in a database the problem would solve itself. Also if Delphi had LINQ capability I could query the objects and arrays that way.

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