I've read a lot of things about restoring data in FragmentActivity but nothing works in my case. I tried a lot of methods to do it but it never worked.
I have a FragmentActivity containing a ViewPager with 6 or 7 fragments. These fragments are containing each one a ListView. The datas in these ListView have been retrieved from web.
I can select an item of the ListView in a fragment to open an new activity showing the detail of the selected item.
When i go back to my FragmentActivity i don't want to retrieve a new time datas from web, but getting it from a bundle or whatever allowing me to display data instantly.
I tried getLast(Custom)NonconfigurationInstance() but it is only called when a real configuration has been changed (such as screen orientation). I also tried onSavedInstanceState in FragmentActivity, in Fragment, whith and without calling the super method... I always get a null savedInstanceState bundle in my onCreate/onCreateView.
I don't have piece of code for you because i go back to zero.
Any ideas please ?
Okay i found a solution but i hate it ! anyway...
When i select an item in the list of my fragment, i put the data i want to restore in the ActivityA with a custom Class that implements Serializable, and i close ActivityA. ActivityB is launching. when i close ActivityB, i put the data iwant to restore in ActivityA. I check if my data are not null (it can be null if i don't come from ActivityB), and if they aren't, i can populate my fragments and my lists without network connection.
It's a very bad way to solve my problem, but i have really no idea why the "savedInstanceState" methods are not working in this case.
Related
So I have a dynamic form that I created with thymeleaf and everything submits just fine to the database, however the child object, which in this case is row, is not being saved to the parent studySet. When I'm in debug mode I can see that the studySet contains an arraylist of however many row objects, but when they're being saved, it's just not being set to the studySet object.
I'll show some code, to see if I'm forgetting to do anything here. If anyone can see my problem and let me know that would be great. Thanks in advance
Here's my post method in my controller
#RequestMapping(value="createStudySet", method=RequestMethod.POST)
public String createSetPost (#ModelAttribute StudySet studySet, ModelMap model, #AuthenticationPrincipal User user) {
studySet.setUser(user);
user.getStudySet().add(studySet);
List<Row> rows = studySet.getRows();
studySet.setRows(rows);
studySetRepo.save(studySet);
return "redirect:/answers";
}
Also this may be helpful, this is a screenshot of my controller in debug mode, so that you can see that there is rows in the studySet.
So, I just want to set those rows to the studySet. Also I realize that this code is probably useless, but it shows an attempt at what I'm trying to do. List<Row> rows = studySet.getRows(); studySet.setRows(rows);.
Also let me know if it would be useful to see my domain objects, and I would add those to the question.
I will try to be as concise as possible. I'm using Flex/Hibernate technologies for my app. I also use Cairngorm micro-architecture for Flex. Because i'm beginner, i have probably misunderstand something about Caringorm's ModelLocator purpose. I have following problem...
Suppose that we have next data model:
USER ----------------> TOPIC -------------> COMMENT
1 M 1 M
User can start many topics, topics can have many comments etc. It is pretty simple model, just for example. In hibernate, i use EAGER fetching strategy for unidirectional USER->TOPIC and TOPIC->COMMENT relations(here is no question about best practices etc, this is just example of problem).
My ModelLocator looks like this:
...
public class ModelLocator ....
{
//private instance, private constructor, getInstance() etc...
...
//app state
public var users:ArrayCollection;
public var selectedUser:UserVO;
public var selectedTopic:TopicVO;
}
Because i use eager fetching, i can 'walk' through all object graph on my Flex client without hitting the database. This is ok as long as i don't need to insert, update, or delete some of the domain instances. But when that comes, problems with synchronization arise.
For example, if i want to show details about some user from some UserListView, when user(actor) select that user in list, i will take selected index in UserList, get element from users ArrayCollection in ModelLocator at selected index and show details about selected user.
When i want to insert new User, ok, I will save that user in database and in IResponder result method i will add that user in ModelLocator.users ArrayCollection.
But, when i want to add new topic for some user, if i still want to use convenience of EAGER fetching, i need to reload user list again... And to add topic to selected user... And if user is in some other location(indirectly), i need to insert topic there also.
Update is even worst. In that case i need to write even some logic...
My question: is this good way of using ModelLocator in Cairngorm? It seems to me that, because of mentioned, EAGER fetching is somehow pointless. In case of using EAGER fetching, synchronization on Flex client can become big problem. Should I always hit database in order to manipulate with my domain model?
EDIT:
It seems that i didn't make myself clear enough. Excuse me for that.
Ok, i use Spring in technology stack also and DTO(DVO) pattern with flex/spring (de)serializer, but i just wanted to stay out of that because i'm trying to point out how do you stay synchronized with database state in your flex app. I don't even mention multi-user scenario and poling/pushing topic which is, maybe, my solution because i use standard request-response mechanism. I didn't provide some concrete code, because this seems conceptual problem for me, and i use standard Cairngorm terms in order to explain pseudo-names which i use for class names, var names etc.
I'll try to 'simplify' again: you have flex client for administration of above mentioned domain(CRUD for each of domain classes), you have ListOfUsersView(shows list of users with basic infos about them), UserDetailsView(shows user details and list of user topics with delete option for each of topic), InsertNewUserTopicView(form to insert new topic) etc.
Each of view which displays some infos is synchronized with ModelLocator state variables, for example:
ListOfUsersView ------binded to------> users:ArrayCollection in ModelLocator
UserDetailsView ------binded to------> selectedUser:UserVO in ModelLocator
etc.
View state transition look like this:
ListOfUsersView----detailsClick---->UserDetailsView---insertTopic--->InsertTopicView
So when i click on "Details" button in ListOfUsersView, in my logic, i get index of selected row in ListOfUsers, after that i take UserVO object from users:ArrayCollection in ModelLocator at mentioned index, after that i set that UserVO object as selectedUser:UserVO in ModelLocator and after that i change view state to UserDetailsView(it shows user details and selectedUser.topics) which is synchronized with selectedUser:UserVO in ModelLocator.
Now, i click "Insert new topic" button on UserDetailsView which results in InsertTopicView form. I enter some data, click "Save topic"(after successful save, UserDetailsView is shown again) and problem arise.
Because of my EAGER-ly fetched objects, i didn't hit the database in mentioned transitions and because of that there are two places for which i need to be concerned when insert new topic for selected user: one is instance of selectedUser object in users:ArrayCollection (because my logic select users from that collection and shows them in UserDetailsView), and second is selectedUser:UserVO(in order to sync UserDetailsView which comes after successfull save operation).
So, again my question arises... Should i hit database in every transition, should i reload users:ArrayCollection and selectedUser:UserVO after save in order to synchronize database state with flex client, should i take saved topic and on client side, without hitting the database, programmatically pass all places which i need to update or...?
It seems to me that EAGER-ly fetched object with their associations is not good idea. Am i wrong?
Or, to 'simplify' :) again, what should you do in the mentioned scenario? So, you need to handle click on "Save topic" button, and now what...?
Again, i really try to explain this as plastic as possible because i'm confused with this. So, please forgive me for my long post.
From my point of view the point isn't in fetching mode itself but in client/server interaction. From my previous experience with it I've finally found some disadvantages of using pure domain objects (especially with eager fetching) for client/server interaction:
You have to pass all the child collections maybe without necessity to use them on a client side. In your case it is very likely you'll display topics and comments not for all users you get from server. The most like situation you need to display user list then display topics for one of the selected users and then comments for one of the selected topics. But in current implementation you receive all the topics and comments even if they are not needed to display. It is very possible you'll receive all your DB in a single query.
Another problem is it can be very insecure to get all the user data (or some other data) with all fields (emails, addresses, passwords, credit card numbers etc).
I think there can be other reasons not to use pure domain objects especially with eager fetching.
I suggest you to introduce some Mapper (or Assembler) layer to convert your domain objects to Data Transfer Objects aka DTO. So every query to your service layer will receive data from your DAO or Active Record and then convert it to corresponding DTO using corresponding Mapper. So you can get user list without private data and query some additional user details with a separate query.
On a client side you can use these DTOs directly or convert them into client domain objects. You can do it in your Cairngorm responders.
This way you can avoid a lot of your client side problems which you described.
For a Mapper layer you can use Dozer library or create your own lightweight mappers.
Hope this helps!
EDIT
What about your details I'd prefer to get user list with necessary displayable fields like first name and last name (to display in list). Say a list of SimpleUserRepresentationDTO.
Then if user requests user details for editing you request UserDetailsDTO for that user and fill tour selectedUser fields in model with it. The same is for topics.
The only problem is displaying list of users after user details editing. You can:
Request the whole list again. The advantage is you can display changes performed by other users. But if the list is too long it can be very ineffective to query all the users each time even if they are SimpleUserRepresentationDTO with minimal data.
When you get success from server on user details saving you can find corresponding user in model's user list and replace changed details there.
Tell you the truth, there's no good way of using Cairngorm. It's a crap framework.
I'm not too sure exactly what you mean by eager fetching (or what exactly is your problem), but whatever it is, it's still a request/response kind of deal and this shouldn't be a problem per say unless you're not doing something right; in which case I can't see your code.
As for frameworks, I recommend you look at RobotLegs or Parsley.
Look at the "dpHibernate" project. It implements "lazy loading" on the Flex client.
i've searched for several hours, and didn't find an answer for my problem.
i'm trying to place comboboxes in a datagrid filled with DYNAMIC data. (the number and the content of these comboboxes always change. i don't know in advance how many columns there are, where i need to use comboboxes. so every single combobox gets a unique dataprovider, which comes from an external source, WHEN the program runs.)
-i found MANY threads discussing this problem, but solving via crappy mxml files, filling the comboboxes inside the sourcecode by hand. i want to point out, that isn't good for me.
-i found a better solution, in which they used some sort of custom itemrenderer to get the data from the internet. (kind of a country chooser thing) but sadly that wasn't good enough, because the number and name of the countries in the world are static more or less, they don't change. so their renderer class didn't depend on any parameters from the main algorithm.
but in my program i calculate the data in my own actionscript objects, then fill an arraylist with that. so at the beginning i load the desired data from the net, and when i get the response of the urlrequest, AFTER that i start to populate the datagrid/combobox.
i can fill any datagrid or combobox without trouble, but to put that combobox inside a datagrid cell seems to be impossible.
could anyone please help? it drives me crazy. i managed to do this in several languages before, c#, java, even php+html, but in flex it looks way too complicated then it should be.
EDIT:
i'm aware, that this amount of network activity could mean some load on the server. i didn't design the philosophy behind it, i just need to wrote a client which meets the expectations. my program looks something like this:
(i'm willing to rewrite any part of it, just to make those nasty comboboxes work)
=========
main.mxml file
this is the main program, i handle some login related stuff here, and set basic design properties for the datagrids. (for example: maxwidth, maxheight, layout constraints etc.)
nothing interesting, except the command when i instantiate the actionscript class, which i wrote to fill the datagrid.
"..<fx:Script>
<![CDATA[
private var myGrid1:MyGridType;
..
somefunction {
myGrid1 = new MyGridType(theDatagridDefinedBefore, "argumentNeededToFillDataGridsWithUniqueData");
}
]]>
</fx:Script>.."
=========
MyGridType.as file
in the constructor i call a urlrequest with the help of the second argument, then add an eventlistener to it. when the data arrives, the eventlistener fires the filler function: i read the results into an arraycollection, then make it the dataprovider for the the datagrid in the first argument.
so far so good.
here comes the trouble with the comboboxes. for a specific number columns, i instantiate my combobox class. let's call that class "MyComboBoxType".
"..
blablabla = new MyComboBoxType(theDatagridDefinedBefore, param1, param2, param3);"
=========
MyComboBoxType.as file
i do nearly exactly the same, what i did in the MyGridType class. call for help from the net with param1-2-3. when i receive the data, fill an arraycollection. maybe set that arraycollection to be the dataprovider for a combobox. AAAAAAAND now i want that arraycollection or combobox to be on the datagrid "theDatagridDefinedBefore".
I know it's not exactly what you're trying to accomplish, but I had a somewhat similar issue in the past. Take a look at How to get the value of a ComboBox within a DataGrid to see if it helps.
If it were me, I would populate the entire ArrayCollection set before binding them to the datagrid if at all possible.
You should build up your custom [Bindable] data structure - say MyGridData class - for the rows in the grid (if you haven't done it yet);
the dataProvider of your grid should
be an Array / ArrayCollection /..
of MyGridData objects.
this step clearly works already, but
for the integrity: override the
getItemEditor function, or specify
it explicitly using mxml, to return
the combobox when needed.
as for the dataProvider of the
combobox, you should specify the
data.comboArray from inside the
renderer class, where data is the
MyGridData instance used by the row
you are processing. (overriding the
set data(value: Object):void
function, you can pre-process it.)
this way, you are working with the
reference of your original instances,
and by the binding you can detect /
show any changes to them directly.
I have a DataGrid.
It's ItemsSource is bound to the ModelView's CompositeCollection through the ViewModel.
The CompositeCollection consists of 2 ObservableCollections.
The display on the grid is fine. I am able to see the collection.
However, when I try to edit one of the rows, I get a crash (NotSupportedException) of:
"'EditItem' is not allowed for this view"
How do I make the rows editable? I need to be able to edit the ModelViews representing each row in the Grid.
Here is the CompositeCollection Property code that I use to bind to the itemssource:
this isn't the exact code since I am not allowed to post the exact code but it is the same logic on how I make the collection
public CompositeCollection ModelViewsCollection
{
get
{
CollectionContainer modelViewContainer;
CompositeCollection modelViewCollection = new CompositeCollection();
modelViewContainer= new CollectionContainer();
modelViewContainer.Collection= this.ModelViewCollection;
modelViewCollection .Add(modelViewContainer);
modelViewContainer= new CollectionContainer();
modelViewContainer.Collection= this.ModelViewCollection2;
modelViewCollection .Add(modelViewContainer);
return modelViewCollection;
}
}
CompositeCollection does not implement IEditableCollectionView which is used by the datagrid to edit.
I have had the same issues, and ended up doing my own fake composite collection on the view model, similiar to what you have, if all you are putting in your collection is two observable collections, its not to hard to track the changes listening to collection changed on both of them. and make your viewmodels collection consist of both of them
You could even do the dirty hack that i did, of rebuilding the ObservableCollection that the grid binds to every time one of the collections change (not elegant i know, but ill go back and optimise when i get time.. i.e. never) With a linq query this stuff is really easy.
Otherwise maybe you could derive from CompositeCollection and try and add the IEditableCollectionView, if you get that working be sure to let me know.
here is the same question on the datagrid forum
I'm using XtraGrid of DevExpress 2.9.5 to display a blotter of dynamic set of lines. The blotter is integrated into another application, this is why it has to be based on UserControl class and also implement a couple of custom interfaces.
public partial class BlotterForm : UserControl, ISMMdiEmbeddable, ISMAssociatedMFCWindow
{
private BindingList<BlotterTrade> fDeals;
....
}
As the data is binded to control using BindedList, any change should be reflected in the form automatically. And if I try to add new line to fDeals like follows:
public void AddDeal()
{
fDeals.Add(new BlotterTrade(1,2,3));
}
... i can see the line, but it's content is rubbish.
I tried to do the same in a small test application. It works ok with only difference that the blotter in test application is based on DevExpress.XtraEditors.XtraForm. To me it looks now that the form of original blotter doesn't overload some method or miss some event. But I cannot find out what exactly is missed.
Can somebody tell me what I do wrong or don't do?
Thanks.
A couple of things:
BindingList doesn't always work too well with DevExpress, and it's suggested to use XPCollection instead.
Do you have any more info about how you setup your columns in the xtragrid? If you use incorrect field names in the column, then they won't show what you're looking for.
If the params you're using (1, 2, 3) are ids stored as fkeys to other objects (not sure if you're using xpo or not) then they won't show up correctly either (there'll likely be a '+' in the cell instead of any values).
[aside] be sure that blottertrade implements INotifyPropertyChanged for better interaction with the grid.
Thanks to everybody for the answers and comments. I think I sorted out the problem. It was actually related to interaction between native C++ and C# layers in my application. The object that was supposed to be displayed in XtraGrid was created in C++ layer, the grid was displayed asynchronously with object construction/deconstruction, that's why at the moment when the grid was ready to display it, the object itself didn't exist. Hence the rubbish. It's good the grid itself was not crashing or firing exceptions.