I'm experiencing an issue refreshing data in XPCollection after commiting some database changes using UnitOfWork.
I have a WinForm with an XPCollection.
The XPCollection uses XpoDefault.Session.
I do some changes through a UnitOfWork:
using (UnitOfWork uow = new UnitOfWork())
{
var photos = new XPCollection<Photo>(uow);
photos[0].Date = DateTime.Now;
uow.CommitTransaction();
}
To get the original XPCollection to update the changes, I've tried the following:
foreach (Photo photo in myXPCollection)
{
XpoDefault.Session.Reload(photo);
}
foreach (Photo photo in myXPCollection)
{
photo.Reload();
}
myXPCollection.Reload()
None of the methods work.The changes are not reflected in the original XPCollection.
They are only visible when I start with a completely new Session. Obviously, this is a big performance problem.
How to get the changes made using UnitOfWork to another Session?
You said:
They are only visible when I start with a completely new Session. Obviously, this is a big performance problem.
That's exactly what you should do. Create a new UnitOfWork each time you want refreshed data. A UnitOfWork is very cheap performance-wise to instantiate. If you have a large collection of Photo objects, you should improve performance by loading only the objects you need by specifying the Criteria parameter in the XPCollection<Photo> constructor.
When you issue Reload() it doesn't fetch anything from the database: it discards any changes and reloads the object from the session identity map. You can read this article and this Support Center issue for more information.
By the way, the DevExpress Support Center is by far the best place to ask DevExpress questions.
Related
I am trying to list the view template’s properties so we can compare them with another old template.
For example what model elements are hidden or have overrides in a given template or which Revit links have been hidden or overridden in a given template.
View Template
(https://www.google.com/search?q=view+template+revit&rlz=1C1GGRV_enUS770US770&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjLndrd2cTbAhVESq0KHX1cAPwQ_AUICygC&biw=1536&bih=824#imgrc=Q0v-pV7Nxl4kfM:)
I’m looking to devise a View Template Compare tool and access to the owner and creator of them.
public void ApplyViewTemplateToActiveView()
{
Document doc = this.ActiveUIDocument.Document;
View viewTemplate = (from v in new FilteredElementCollector(doc)
.OfClass(typeof(View))
.Cast<View>()
where v.IsTemplate == true && v.Name == "MyViewTemplate"
select v)
.First();
using (Transaction t = new Transaction(doc,"Set View Template"))
{
t.Start();
doc.ActiveView.ViewTemplateId = viewTemplate.Id;
t.Commit();
}
}
With Revit API you can access with:
GetTemplateParameterIds Method / ViewTemplateId Property
The Revit API exposes almost all the ViewTemplate properties.
For instance this method returns all the Visibility/Graphic Overrides for a specific category:
https://apidocs.co/apps/revit/2019/ed267b82-56be-6e3b-0c6d-4de7df1ed312.htm
The only thing I couldn't get for a ViewTemplate are the "includes", but all the rest seems to be there.
Update:
The list or properties "not included" can be retrieved with GetNonControlledTemplateParameterIds().
Yes, and no.
Yes, I guess you can use Forge Model Derivative API to export RVT file and then build a dashboard around the View Templates data. That's assuming that View Templates data actually gets exported when the model is translated. That data is not attached to any geometry so I would not be surprised if it was skipped. The question here is why? This is like renting a 16-wheel truck to move a duffel bag across the street.
No, if your intention is to directly interact with the RVT model. Forge can view it, but to push anything back or request changes to the model, is not available yet. Then again, I am not even sure that the view template data is available via model derivative exports.
This brings me another alternative. Why not just collect the data using Revit API, the standard way and then push it out to a Database and build on top of that? There is no reason to employ Forge for any of that.
Thanks Jeremy, I had dig into your amazing website and also some solution that Konrad post in the Dynamo Forum about this. In Revit seems pretty achievable, you filter the View that is View Template and then extracts these properties, is it correct?.
I am wondering if someone can point me in the right direction with Forge.
Some amazing guys are developing a BQL https://www.retriever.works/.
BQL(Building Query Language) is a query language for buildings, similar to how SQL is a query language for databases. It is fast and flexible. BQL helps improve efficiency for QA/QC (quality assurance and quality control), and building data extraction without leaving Revit. I am also trying these and I would like to understand if there are some works where I could start with Forge next week about this.
When we add new properties to our custom AuthUserSession based session DTO, we either need to invalidate users active sessions and force them to re-login, or migrate their sessions (either in mass, or in lazy fashion). If this is not done, expected properties will not be filled, and adds a lot more complexity to the code relying on those properties.
I dug around and looked for any events around hydration of sessions from cache, but didn't see any easy place to tie in and determine if the session should be refreshed.
Any suggestions on where to plug in such logic in the flow where it will always happen before some session object is used by a ServiceStack Service or Razor view?
For Caching providers that implement ICacheClientExtended you can access all Sessions with:
var sessionPattern = IdUtils.CreateUrn<IAuthSession>(""); //= urn:iauthsession:
var sessionKeys = Cache.GetKeysStartingWith(sessionPattern).ToList();
var allSessions = Cache.GetAll<IAuthSession>(sessionKeys);
Otherwise I've just added a custom hook to be able to filter a session (in this commit), by overriding OnSessionFilter() in your AppHost, e.g:
public override IAuthSession OnSessionFilter(IAuthSession session, string id)
{
return base.OnSessionFilter(session, id);
}
This change is available from v4.0.49 that's now available from MyGet.
My collegue helped me with starting programming in c# although I had no experience but I like it. All went well until I came across some problems we both can't fix. He uses SQL himself but started me up with LINQ.
To do a LINQ-query I use this object : _oDBConnection (in clsApplication.cs)
So when opening the programm this object is built. But it creates some problems:
When saving a new object (putting data into table), I cannot load those values with a query. I need to restart the programm.
When running 2 instances of the programm, one is not getting the latest values when changed in the other (but it is showing the new ones but not the changed ones!)
According to these problems I can only conclude that when I call clsApplication._oDBConnection.tblTAble a second time it is not relinking again to the db but is giving me the old db-states back.
This is the code he built:
public static DBReservationDataContext _oDBConnection;
private static frmMain _fMain;
public clsApplication()
{
Thread.CurrentThread.Name = "main";
clsErrorLog.ErrorLocation = "C:\\Software\\ErrorLog";
clsErrorLog.setPassword("*****");
clsErrorLog.LockApplication += new clsErrorLog.dLockApplication(lockApplication);
_oDBConnection = new DBReservationDataContext();
_fMain = new frmMain();
_fMain.Show();
}
What can I do to fix this problem?
Example:
although present in the database, it crashes on this query because the entity with id == iID is not found. But the iID is correct and it does exist in the database. The query will work after closing and restarting the programm. Then the clsApplication is called again.
public clsReservationDetail(int iID)
:this()
{
_oReservationDetail = (from oReservationDetailQuery in clsApplication._oDBConnection.tblReservationDetails
where oReservationDetailQuery.ID == iID
select oReservationDetailQuery).First();
}
thx in advance
Your data context will have a Refresh method which will clear any cached results, and should allow your query to complete with no problems
The static keyword makes it so that you have one reference per AppDomain. That is the wrong way to use DataContext instances.
Each instance of DataContext tracks the objects it has seen. This is for consistency. If you get a Customer instance with CustomerID = 4 from one query, you should get the same Customer instance from another query that returns the CustomerID = 4 record.
If you want to see the changes in the database, you must
1) Tell the datacontext to stop tracking changes. This must be done before the first query and makes the datacontext instance unable to SubmitChanges (since it can't track them anymore).
OR
2) Tell the datacontext to Refresh each instance you suspect has changed. If you do that, you should specify how resolve the conflict between your local changes and the remote changes - the simplest way of resolving this conflict is to have no local changes.
OR
3) (The right way) Make a new DataContext instance and load the record with that!
Also note: Since DataContext implements IDisposable, you are required to call Dispose when you are done with each instance even when exceptions occur. The using block is a good way to get that to happen.
I recently had a problem with multiple form posting in an ASP.NET MVC application. The situation was basically, if someone intentionally hammered the submit button, they could force data to be posted multiple times despite validation logic (both server and client side) that was intended to prohibit this. This occurred because their posts would go through before the Transaction.Commit() method could run on the initial request (this is all done in nHibernate)
The MVC ActionMethod looked kind of like this..
public ActionResult Create(ViewModelObject model)
{
if(ModelState.IsValid)
{
// ...
var member = membershipRepository.GetMember(User.Identity.Name);
// do stuff with member
// update member
}
}
There were a lot of solutions proposed, but I found the C# lock statement, and gave it a try, so I altered my code to look like this...
public ActionResult Create(ViewModelObject model)
{
if(ModelState.IsValid)
{
// ...
var member = membershipRepository.GetMember(User.Identity.Name);
lock(member) {
// do stuff with member
// update member
}
}
}
It worked! None of my testers can reproduce the bug, anymore! We've been hammering away at it for over a day and no one can find any flaw. But I'm not all that experienced with this keyword. I looked it up again to get clarification...
The lock keyword marks a statement block as a critical section by obtaining the mutual-exclusion lock for a given object, executing a statement, and then releasing the lock
Okay, that makes sense. Here is my question.
This was too easy
This solution seemed simple, straightforward, clear, efficient, and clean. It was way too simple. I know better than to think something that complicated has that simple a solution. So I wanted to ask more experienced programmers ...
Is there something bad going on I should be aware of?
No it's not that easy. Locking only works if the same instance is used.
This will not work:
public IActionResult Submit(MyModel model)
{
lock (model)
{
//will not block since each post generates it's own instance
}
}
Your example could work. It all depends on if second-level caching is enabled in nhibernate (and thus returning the same user instance). Note that it will not prevent anything from being posted to the database, just that each post will be saved in sequence.
Update
Another solution would be to add return false; to the submit button when it's being pressed. it will prevent the button from submitting the form multiple times.
Here is a jquery script that will fix the problem for you (it will go through all submit buttons and make sure that they will only submit once)
$(document).ready(function(){
$(':submit').click(function() {
var $this = $(this);
if ($this.hasClass('clicked')) {
alert('You have already clicked on submit, please be patient..');
return false;
}
$this.addClass('clicked');
});
});
Add it do you layout or to a javascript file.
Update2
Note that the jquery code works in most cases, but remember that any user with a little bit of programming knowledge can use for instance HttpWebRequest to spam POSTs to your web server. It's not likely, but it could happen. The point I'm making is that you should not rely on client side code to handle problems since they can be circumvented.
Yeah, it's that easy, but - there may be a performance hit. Remember that a Monitor lock restricts that code to be run by only one thread at a time. There is a new thread for each HTTP Request, so that means only one of those requests at any given time can access that code. If it's a long running procedure, or a lot of people are trying to access that part of the site at the same time - you might start to sluggish responses.
It's that easy, but be careful what object you lock on. It should be the same one for all the threads - for example, it could be a static object.
lock is syntactic sugar for a Monitor, so there is quite a bit going on under the cover.
Also, you should keep an eye out for deadlocks - they can happen when you lock on two or more objects.
I get System.NotSupportedException: An attempt has been made to Attach or Add an entity that is not new perhaps having been loaded from another DataContext when I want to update an object's with child entities.
The scenario is like this:
I have a SubscriberProvider that allows me to create subscribers.
var provider = new SubscriberProvider(); // Creates a new repository with own datacontext
var newSubscriber = new Subscriber
{
EmailAddress = emailAddress,
};
newSubscriber.Interests.Add(new Interest{
Id=1,
Name="cars"
});
provider.Subscribe(newSubscriber);
On a normal subscribe page, this works fine.
Now I have a linq2sql Member class(retrievable by a MemberRepository) and I want to extend it to have a helper subscribe method like so:
var repository = new MembershipRepository(); // Holds its own datacontext
var member = repository.Get("member1");
member.Subscribe(); // transfer member's info and interests to subscriber's table
The exception occurs when SubscriberProvider tries to add interests of the member.
Commenting out
newSubscriber.Interests.Add(new Interest{
Id=1,
Name="cars"
});
will make member.Subscribe() work.
member.Subscribe() is simply:
public void Subscribe(bool emailIsVerified, bool receiveEmails, bool sendDoubleOptIn)
{
var provider = new MailingListProvider();
provider.Subscribe(EmailAddress, emailIsVerified, receiveEmails, CountryId, sendDoubleOptIn, ConvertInterests(MemberInterests.ToList()));
}
So what's causing the child entities(Interests) to lose their datacontext when I do member.Subscribe() and how do I go about fixing this?
It seems there's some code missing here, but I'll take a stab anyway because I think I have an idea what's going on.
If you have a different DataContext created for your MembershipRepository and your SubscriberRepository you're going to have issues related to entities "having been loaded from another DataContext." (as the Exception you posted points out). You can't just take an object out of one DataContext and save it into another.
It seems that you might have an architectural issue here. Should these 2 repositories actually be separate? If so, should they have completely different DataContexts? I would probably recommend using Dependency Injection to inject your DataContexts into your Repositories. Then you can decide how to cache your DataContexts.
That line of code you commented out is being flagged by the DataContext as a new record, even though it's likely that the record already exists, due to the error message.
Change the line to:
newSubscriber.Interests.Add(DataContext.Interests.Where(a => a.Id == 1).Single());
Now, the DataContext will know that record is one that already exists, and won't try to add it as an Insert to the ChangeSet.
Found the solution to this myself. Turns out it was the ConvertInterests() method causing it. The converted interest object had an invalid declaration which compiled ok.
Thinking the code was simple enough, I didn't create a test for it. I should have known better!