Two views in my application need to load same information when restoring state. My idea was, to avoid saving it twice, to have one view create another in init orcreatePartControl if it wasn't created yet. However,
PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().showView(...)
doesn't work there, as getActivePage() returns null. Is it possible to work around this?
Delegate to a manager or service to load/maintain/save the shared state. That will ensure the first access initializes your information. When the view is instantiated just go to the manager and retrieve the information. If the user never instantiates your view, then you never had to do the extra work.
In the general case, you can't create/instantiate one view while creating/activating another view. Eclipse won't allow it, and will generate ERRORs in the error log.
EDIT:
3 standard persistence patterns I've seen used (and/or misused :-) are:
1) Have your plugin get its state location and simply serialize you state out there. (location provided for free if you subclass org.eclipse.core.runtime.Plugin) You can do it in your activator stop(BundleContext) method. You can uses classes like org.eclipse.ui.XMLMemento to serialize to/from XML if you don't already have a solution.
2) if you subclass org.eclipse.ui.plugin.AbstractUIPlugin you can use org.eclipse.ui.plugin.AbstractUIPlugin.getDialogSettings() to store your state. Potentially a little bulky as you would have to keep it up to date.
3) have your common manager update a preference, potentially using another serialization technique.
Related
I thought I had a common business case but cannot find an appropriate solution for that.
So, suppose I have LoaderController which has a number of database actions like load, save, etc. It loads and saves the objects of a single type (i.e. this is not a generic controller). BUT: it can load objects from different databases - that's the point.
So, if a user calls /db1/load - the system loads data from database db1, /db2/load - from database db2, etc. Also, I have a kind of a shared environment, so I can't be sure that the first segment is always the database name. There might be other cases like /report/id which don't correspond to LoaderController but have to live with that type of route "/x1/x2" as well.
Well, the basic idea is to somehow register all my database endpoints like (pseudocode):
Register("db1", controller = typeof(LoaderController), parameter="ConnectionStringToDb1"), but I cannot understand how to do that. Not only registering that type of route is an issue but also pushing the connection string parameter into the particular controller in any way.
In our company, repository objects must be created with original language EN.
Is there a way to check the logon language in case of creating a new object in the ABAP repository?
Desired behaviour:
SE80 - Create program/class/data element/table/....
==> user exit/badi checks the logon language. When it is not 'EN', the creation will be refused.
regards,
Umar Abdullah
I know there is a exit for this but I haven't remember exact name. You can use general purpose for finding exit. Go to SE24 and open CL_EXITHANDLER class, find GET_INSTANCE method and add break point. Then start creating item, it will pause on debugger multiple times, try to find suitable one.
As #mkysoft suggested, you may implement a check in the BAdI CTS_REQUEST_CHECK, method CHECK_BEFORE_ADD_OBJECTS, which is invoked when the object is about to be attached to a transport request. Raise the exception CANCEL to make the attachment fail (and so the object is not created too).
EDIT: sorry, ignore my answer, "this method is NOT released for Customer usage" as said in note 2150125 - Method CHECK_BEFORE_ADD_OBJECTS not triggered
DISCLAIMER: THE METHOD DESCRIBED HERE IS ABSOLUTELY NOT RECOMMENDED.
As correctly pointed out by the other members there is no standard and customer-exposed method to achieve your requirement, but if you absolutely must enable this check during creation you can use the below method. As well as the previously offered to you, it also involves modification of SAP standard.
There is a system BAdi CTS_TADIR_SUBSCREEN that is located inside enhancement point CTS_ES_TADIR_POPUP. They are SAP internal and not released for customer usage, so do this at your own risk.
Implementation procedure:
Step 0. First thing you need to change is a SAP internal usage flag, for which you need Object Access key which can be obtained from SAP or from SAP partner that made the implementation in your org. In virgin state this BAdi throws the error if you try to implement it
So hereinafter we assume that you already ticked off this checkbox in BAdi settings
Step 1.
In order to implement the BAdi one need to implement enhancement spot prior to that. This is the most complicated part, because despite we disabled internality flag the SAP-namespaced enhancements must be stored only in SAP-namespaced objects. By SAP namespace I mean non-Z, non-Y and non-T (Test). This means to implement this enhancement, besides modifying the enhancement definition, one need to create, for example, CTS_ES_TADIR named enh.impl., and save it to non-Z package, which you also need to create. Your enhancement implementations selector should look somehow like this
On the above screen only the second will work, all the rest Z will not.
Every non-Z object need Object Access Key, remember? Too bad. But just to show the proof-of-concept, I will proceed.
Step 2. After you created the enh. implementation in SAP-namespace it will propose you to create the BAdi implementation. The same principle applies here: only SAP-namespaced container for SAP-namespaced objects, hence CTS_TADIR_SUBSCREEN should have implementing class for example CL_TADIR_SUBSCREEN. During the creation of enhancement you will see many warnings
but finally you should have something like this, where all system-named objects are created and the enhancement/BAdi is activated.
Step 3. In order to get the BAdi working we need to enable this subscreen processing
during the playing with enhancement I found out that BAdi class is not being triggered standalone, without screen events not enhanced, so to make it work you need to touch a screen enhancement for screen 100
If you do not wanna modify screen elements logic, just put the dummy enhancement in SHOW_TADIR dialog module in the end of the include LSTRDO18
PROCESS BEFORE OUTPUT.
MODULE SHOW_TADIR. "<-- create the dummy enhancement here
CALL SUBSCREEN subs_info INCLUDING gv_badi_prog gv_badi_dynnr.
for example declaration statement like I did
Step 4. Activate your created BAdi class and put the necessary logic there. I wasn't able to trigger method GET_DATA_FROM_SCREEN, but PUT_DATA_TO_SCREEN worked fine
If we put this simple processing for your requirement
METHOD cts_if_tadir_subscreen~get_data_from_screen.
IF object_data-l_mstlang <> 'E'.
MESSAGE 'Objects in non-English languages are not allowed!' TYPE 'A'.
ENDIF.
ENDMETHOD.
it will not allow creating objects in languages other than English.
The check in method get_data_from_screen is being done before showing the screen so language is determined from system logon settings. If to play more with this BAdi, I suppose the method GET_DATA_FROM_SCREEN can also be enabled, which will make it possible to check user input, i.e. the case when the user gonna change the default language.
The code:
public ChatMessage[] GetAllMessages(int chatRoomId)
{
using (ChatModelContainer context = new ChatModelContainer(CS))
{
//var temp = context.ChatMessages.ToArray();
ChatRoom cr = context.ChatRooms.FirstOrDefault(c => c.Id == chatRoomId);
if (cr == null) return null;
return cr.ChatMessages.ToArray();
}
}
The problem:
The method (part of WCF-service) returns an empty array. If I uncomment the commented line it starts working as expected. I have tried turning of lazy loading but it didnt help.
Also, when it works, I get ChatMessages with a reference to ChatRoom populated but not the ChatParticipant. They are both referenced by the ChatMessage-entity in the schema with both Id and Navigation Properties. The Ids are set and points to the right entities but on the client-side only the ChatRoom-reference has been populated.
Related questions:
Is an array the preferred method to return collections of EF-entities like this?
When making a change in my model (edmx) Im required to run the "Generate Database from Model..."-option before I can run context.CreateDatabase(). Why? I get some error message pointing to old SSDL but I cant find where the SSDL is stored. Is this created when I run this "Generate Database..."-option?
Is it safe to return entire entity-graphs to the client? Ive read some about "circular reference exeptions" but is this fixed in EF4?
How and when is references populated in EF4? If I have lazy-loading turned on I suspect only entities I touch is populated? But with lazy loading turned off, should the entire graph be populated always then?
Are there any drawbacks of using self-updating entities over ordinary entities in EF4? I dont need self-updating right now but I might do later. Can I upgrade easily or should I start with self-updating from the start?
Why cant I use entity-keys with type string?
Each of your questions needs a separate answer, but I'll try to answer them as briefly as possible.
First of all, in the code sample you provided, you get a ChatRoom object and then try to access a related object that is not included in your query (ChatMessages). If lazy loading is turned off as you had suggested, then you will need the Include("ChatMessages") call in your query, so your LINQ query should look like this:
ChatRoom cr = context.ChatRooms.Include("ChatMessages").FirstOrDefault(c => c.Id == chatRoomId);
Please ensure that your connection string is in your config file as well.
For the related questions:
You can return collections in any way you choose - I have typically done them in a List object (and I think that's the common way), but you could use arrays if you want. To return as a list, use the .ToList() method call on your query.
I don't understand what you're trying to do here, are you using code to create your database from your EDMX file or something? I've typically used a database-first approach, so I create my tables etc then update my EDMX from the database. Even if you generate your DB from your model, you shouldn't have to run CreateDatabase in code, you should be able to run the generated script against your DB. If you are using code-only then you need to dump the EDMX file.
You can generally return entity graphs to the client, should handle ok.
EF4 should only populate what you need. If you use lazy loading, it will automatically load things that you do not include in your LINQ query when you reference them and execute the query (e.g. do a ToList() operation). This won't work so well if your client is across a physical boundary (eg a service boundary) obviously :) If you don't use lazy loading, it will load what you tell it to in your query and that is all.
Self tracking entities are used for n-tier apps, where objects have to be passed across physical boundaries (eg services). They come with an overhead of generated code for each object to keep track of its changes, they also generate POCO objects which are not dependent on EF4 (but obviously contain generated code that would make the tracked changes work with the EF4 tracker). I'd say it depends on your usage, if you're building a small app that's quite self contained, and don't really care about separation for testability without the infrastructure in place, then you don't need to use self tracking entities. I say only use framework features when you need them, so if you're not writing an enterprise scale application (enterprise doesn't have to be big, but something scalable, highly testable, high quality etc) then no need to go for self tracking POCOs.
I haven't tried but you should be able to do that - that would be a candidate for a separate question if you can't get it to work :)
I was wondering if there is a way to share an NSManagedObject between two or more NSManagedObjectContext objects running in the same thread.
I have the following problem: I have one main context shared through all my code in the application and several different contexts that are created for each remote fetch request that I issue. (I created a custom class that fetches remotely and inserts all the objects found in the server in his own NSManagedObjectContext). Those fetch requests may run simultaneously since they use NSURLConnection objects that may end at different times. If the same remote object gets fetched by different connections, I will end up with duplicates at the moment of saving and merging the context with the main one. (That is, objects that have the same remote ID but a different objectID).
One possible solution would be to save (and so persist) every object as soon as it is created but I can't do that because it may have some relationships that may still have not been filled and won't validate during the save operation.
I'm really looking forward to a method that allows you to share the same non-persistent instance of an object between context. If anybody has encountered this issue and came up with a solution, I would be pleased to know!
Context cannot communicate between each other save through their stores. However, you can insert a managed object with a nil managed object context and it will be independent (albeit without relationships) of any context. You could pass that independent managed object around however you wished and insert it into a context when you needed to persist it. This is dangerous but possible.
However, if you're not running each connection on a separate thread then you don't gain anything by having multiple context. Each connection object will activate its delegate in sequence on the main thread. In this case, your easiest solution would be to use the same delegate for all the connections and let the delegate handle the insertions into a single context. To prevent duplication, just do a fetch on the remoteID and see if you get back an extant object before inserting a new object for that remoteID.
I don't think what you want to do is possible. I mean if you want to share changes between different contexts, you got to use notifications and merge it whenever did save or did change occur. But in your case, I'd say just use 1 context and save in the end. Or a less elegant way: save all the remote ids temporary in your app and check before inserting new ones. In this case, you can continue use multiple contexts and save after each didfinishloading.
Currently I am struggling with a Entity Framework issue. I have a wcf service that sits on top of the ef framework, and allows queries to the framework. At some point the user is able to request a file from the framework. The files are referenced by solution entries, so when you request a file from a solution, the reference is loaded to gain access to the file store.
That all works fine, but from that point onward, whenever you do another query that returns that solution entry, the whole file gets attached to the return result. I need some way of detaching or unloading the reference, such that the result entries will only contain an unloaded reference to the file store again.
I have tried to create a new context and query that context to retrieve information from, but when I do that, the entity in the original context is also changed.
I have tried to detach the entity from the original context and then query from the new context. That does not work either.
I have found one way of doing this. For all the non file-download queries, I detach the result entity, and send that over the wire. I am not sure if that is the best way to go about it though.
I hope someone might be able to provide some insight, thanks for the effort.
The issue you are experiencing is probably do to Change Tracking, which is on by default.
Possible Solution:
Disable Change Tracking with MergeOption.NoTracking
using (MyEntities _context = new MyEntities())
{
_context.Widgets.MergeOption = MergeOption.NoTracking;
return _context.Widgets.ToList();
}
This article may help to point you in the right direction on how to handle this issue if the solution above does not work.
I struggled with a similar issue recently. The problem was the result of the context maintaining a reference to the object I was using (obviously). Every time I made a change to an object of the same type, even when obtained with a new context (so I thought), the object was being changed.
With help from one of my peers, we determined the context was hanging around due to the way I was registering it with my IoC container (lifestyle per web request). When I changed the lifestyle to transient (which definitively provided a new instance) then changes to objects of the same type were unaffected.
Hope this helps.