i have a Grid showing details of a Person object. When a row is selected, i am showing the details in a separate Region.
When the user edits e.g. the First Name Textbox in the Details View, the changes immediately get reflected in the Grid.
When the user decides to Cancel the edit, i can undo the changes by replacing the object in the Details view, but the changes in the Grid view are not reverted.
in OnNavigatedTo of the Details View i have:
_persons = navigationContext.Parameters["persons"] as List<Person>;
i make a MemberwiseCopy of _persons[0] and show _persons[0] in the Details View:
PersonEdit = _persons[0];
_savedPerson = _persons[0].Clone();
All fields of the details view are bound to PersonEdit.
Changing the FirstName, which is bound to PersonEdit.FirstName the Grid shows the changed value.
When the user presses the "Cancel Edit" button, i want to restore the saved Copy.
tried both:
PersonEdit _savedPerson;
_persons[0] = _savedPerson;
This restores the changes done before the edit in the Details view, but the grid stays unchanged.
Any ideas?
Thanks,
Helmut
I think you should invest some time in building an undo-(redo?)-infrastructure. Commanding comes to mind.
Until then, because of
When the user edits e.g. the First Name Textbox in the Details View, the changes immediately get reflected in the Grid
you should restore all the original values and the changes (i.e. the undo) will also be directly visible.
So do not clone and edit the clone, but keep the clone around and copy every editable value from the clone to the original object when the user clicks the undo-button.
Side note: if you use the default Clone implementation, you better be 110% sure that this is correct for your domain (and will be in the future).
Related
I have a page with two panels. The first panel is where create and update happens, and the second panel is a list of stuff that I just added. Sort of like this (below). The second panel updates the list every X second.
Each list has an edit button that takes it back to the first panel. I pass the entity through the button's function and fill up the values in the edit panel. Here's the weird thing, when I try like say edit an entity in the list, an the interval happens to update the list, the entity gets refreshed and all my changes are never saved.
I tried just passing the id though the button then doing a get request for that particular entity and performing the edit, but the interval takes place and my changes are reverted.
I think my only option is to do angular.copy(myEntity) and do the edits from there, and then manually do the PUT request. Is there another way for the edited entity not to be affected by the interval aside from doing an angular.copy()? Pausing the interval while something is being edited is not an option, since client wants the list to update even when he's editing something.
If you need to keep your data up to date by refreshing every few seconds, i recommend implementing a bool HasChanges() function in your controller. This will return true if the data has changed, and false if not. That way you can decide if you want to pull and refresh new data, or deffer it until your editing is done without overwriting your unsaved changes.
How can I reset my viewmodel when the user clicks new button on the view that has the viewmodel as it's datacontext?
For example:
If I have a view NewCustomer and upon save, the data is saved to the DB and the newly created account number is displayed. But when the user clicks the New button in the screen, I want the view (viewmodel) to be reinitialized. Or if the user clicked cancel in the screen to clear all changes.
How can I achieve this? I am using Prism 5.0 and Unity as my container.
If I used IRegionMemberLifetime, I can clear the viewmodel data when I navigate away and navigate again to the view (by setting the KeepAlive as false on clicking New button before navigating away). But I want the form to be cleared without navigating. Can this be done?
You could have a screen/workspaceViewModel, and another ViewModel wrapping your data.
So two classes: CarScreenViewModel and CarViewModel.
The CarScreenViewModel would have a property, say CurrentCar, which reflects what is currently selected in the screen. Then, when clicking the Create button, you simply set:
CurrentCar = new CarViewModel();
Resetting partially loaded data will only lead to behaviour that is hard to reproduce. It is better to start with a fresh instance.
Your standard approach will be something like below
ViewModels
CustomersContainerViewModel which contains
a collection of CustomerViewModel s
and ICommands like
CreateNewCustomer
DeleteExistingCustomer
UpdateExistingCustomer
Your View will contain
the CustomersContainerView which will contain
a collection of Customer Objects in your required UI element
a button to Create new customer (which will launch a new screen which contains the newCustomer fields it can also contain cancel, which will just close the form)
a button to delete (can also be a ContextMenu)
a button to update (can also be a ContextMenu) which will launch a customer form filled with details from DB.
Hopefully this makes some sense... Let me know if you have problem with any of the above
Update - Forgot to add. NewCustomer Command will add a new Customer object to your CustomerCollection and that should open a NewCustomer form (or whatever you chose) for user to input the customer details. Cancel/Delete will just remove that record from the collection. Delete will update the DB as well in addition
In my case
yourViewName.variableName.postValue("")
We have a rowediting plugin on grid where a button of one trigger field changes some other values of the record (we are loading some remote data which get applied to the record). The values that get changed in background are most commonly not editable, so they are just rendered. Basically the remote loading of the data works fine, meaning the record get changed and all data get save but we have the following problems:
1.The rowediting plugin does not show the changes that where applied to the record fields
2.Setting the changes via record.set() cause the store to sync immediately and not on clicking the "save" button of the editor.
So how can we make the editor to show the changes applied in the background and how can we apply these changes in a way so that they get saved along with the other edited fields.
Thanks in advance for any help!
This should not be that complicated, you just need a reference to your active editor instance. You can then either
reload the record into the form by calling loadRecord() again. But note that this may overwrite any changes that where made by now within the editor
or (for the second way I expecting the values to be exactly the same as in the record in manner of key:value definition - short: no special mapping is required)
apply the new data to the record by calling either set (note that this will trigger sync if you have autoSync turned on) or by using Ext.apply(recinstance.data,newvalues) and editorinstance.getForm().setValues(newValues)
My screen has a list of objects of type Person, and a form that displays the person properties (name, address, weight, etc.) via databinding.
I want to be able to:
Click in a button "Edit properties", and start modifying the person's properties (I can already do that using Commands in the ViewModel);
If I click "Cancel", the edited info "rollback" to the original unmodified values of that person;
If I click "Save changes", JUST THEN the person's name changes in the person list.
My problem right now is that, as I am editing the forms, the original properties are updated, so to say, in realtime, and if I decide to cancel, I have not the original values to "go back".
I considered to Clone the selected person, but that seemed to be odd. I think a better approach would be to change only the text properties of the field, and update back only when clicking to submit changes, but I don't know how to do it, specially how to preserve databinding consistency.
When you bind, use UpdateSourceTrigger=Explicit. That will tell XAML not to update the source binding until you tell it to. Then, when your Save button is clicked, you can call UpdateSource on the binding to push the contents of your controls back to the Person object, something like:
var nameBinding = nameTextBox.GetBindingExpression( TextBox.TextProperty );
nameBinding.UpdateSource();
To cancel, use UpdateTarget instead, which will push the data in the Person object back to your control.
You can try it with this Undo/Redo approch
http://blog.notifychanged.com/2009/01/30/using-the-viewmodel-pattern-to-provide-undo-redo-in-wpf/
Or
You could have a a Current and Previous property created in View model to which is going to hold the edited values and the other will have original value. The required action of rollback can be performed be reassigning the values
There are also open-source projects available to help with this, including http://undo.codeplex.com/
I have a series of views that are to be displayed depending on the currently selected item in a tree within a parent view. These views are created and registered with the region during the initialization method of the parent view and are being correctly deactivated/activated, therefore giving the effect of swapping in/out the correct view. These views have a single underlying viewmodel as their datacontext, which contains data objects supporting INotifyPropertyChanged.
This solution works if there are no currently outstanding edits in progress within the child view but if there is a edit in progress in a view (i.e. the user has changed the contents of a description but hasn't clicked out of the text box) and that view is deactivated (i.e. the a different tree item is clicked within the parent view, thus causing a de-activation to occur) a NullReferenceException is being thrown in the NotifyPropertyChanged() of the underlying data object attached to the now deactivated view.
What seems to be happening is this:
An edit is started by the user in the child view
The user clicks an item in the tree in the parent view
The controller picks up the change in the selected item in the tree
The current child view is deactivated
The new view is activated
The change from the edit happens to the underlying data object (the set method is getting called)
A change notification event is generated by the data object as a result of this change
A null reference exception is thrown.
Presumably, this change notification event is being sent to the now de-activated view, but the view is not null.
I have not tried this myself, but I believe one solution was to listen for the deactivate event of the view using IActiveAware and cancel any editing.
See if this link helps.