I have 2 webparts which are connected, where the provider sends a string to the consumer.
However it fails to work if I put any TextBox controls in the consumer webpart. (works fine if I use a Label or Literal control.
The idea is that the consumer is to be composed of form controls like TextBoxes.
e.g. the codeproject sample at http://www.codeproject.com/KB/sharepoint/ConnectingCustomWebParts.aspx
Works fine... until you replace the consumer Label control with a TextBox.
Any help gratefully received.
Well, if this still needs an answer....
Why it would work with one control and not another, I'm not sure. The reason I couldn't get it to work consistently as is coded in that sample is due to the issues brought to fore in this article. The data just isn't always there in the create controls part of the web part life cycle. I had much better luck getting my data and putting it somewhere, either the session or the viewstate during the ConnectionConsumer event, then setting the value to the control that needed to display it in the OnPreRender event, or just somehow binding to the control, say in a grid, and just calling refresh on the List I was using as a datasource in the OnPreRender, calling Refresh in the create controls didn't work reliably, only in OnPreRender.
Once I truly grokked the web part lifecycle, things became much simpler for me, and finally taught me why in Java portlets they went with the post/redirect/get cycle to try and avoid this very granular coordination between various portlets on a page.
Related
I am a newbie to xaml and windows app dev so sorry if this question might seem silly.
I created a textbox and in the designer I right clicked it and selected edit template=>edit a copy and put it into my custom dictionary.
In the control template for this textbox I saw visual states like disabled,focused and so on. And I modified them and run the mobile app and observed that my changes work like changing border color when textbox is focused.
But in order for this to work somebody has to call
VisualStateManager.GoToState("Focused")
when the textbox is focused so who is calling this because I don't see any visual transitions in the control template so how is this happening?
The code in the control itself is calling VisualStateManager.GoToState(...) .
When you start implementing your own custom controls, you might subscribe to events you have available and transition states based on your own logic. Here is an example of a custom control with its own two custom states.
https://github.com/xyzzer/WinRTXamlToolkit/blob/master/WinRTXamlToolkit/Controls/WatermarkTextBox/WatermarkTextBox.cs
XAML is a compiled language, and if you've looked extra close, what happens under the hood, is that the class behind your xaml has the same namespace as your xaml code.
This means (for no practical purpose) that compiling your program turns all of that XAML into C# code before then going over to MSIL and eventually execute as a binary program.
Much of the state changes that happen are event based, and TextBox, like all other user controls, will transmit a message and listen to messages. The Page that contains the TextBox will probably be the one that transmits a state change whenever one of it's children gets focus, and as a good control, the TextBox listens for this event and reacts to it.
I have an xpage with a bunch of controls on it. One of them is a simple label that I'm updating with a partial refresh every five seconds. (I'm implementing a document locking scheme, and the label indicates whether someone has locked the document.) A button on the page fails to execute its event handler if I press it while the partial refresh of the label is occurring. At other times, it works fine. Is this a known issue, or is there perhaps something else going on that may explain this behavior?
(I'm unable to post sample code, unfortunately.)
You need to change your approach. Instead of a partial refresh, have an independent Ajax call to an XAgent for your locking (IMHO 5 sec is way to frequent, the WebDAV standard uses 30sec).
The openNTF WebDAV project has locking code you might be able to repurpose for your needs.
The independent Ajax call frees up the jsf lifecycle to run your other events.
I'm working in a legacy application using MFC.
We have a mechanism to enable/disable controls depending on some business logic.
This mechanism is implemented in the CView-derived class. The way it works is all the views in the application derived from a common CView-derived class (CBaseView) and on the PreTranslateMessage all controls of the view are enabled/disabled.
This worked fine so far because all controls send at least WM_PAINT message when they need to be painted. So the system worked without the user having to move the mouse or anything. I recently added some drawing features and I had to use WS_EX_COMPOSITE to get ride of some flickering. With this flag activated my CView-derived class is not getting any called to PreTranslateMessage when creating the view....so the controls are not disabled until the user moves the mouse over the control.
I understand there is no way to send WM_PAINT using WS_EX_COMPOSITE but is there other message I can use to get the same behaviour???
Edited:
I am currently using the OnIdle approach but it has a big drawback, the windows doesn't become idle until after drawing all the controls...so when you enter the screen al controls are enabled and inmediately they are disabled...this makes a quite ugly effect!
More solutions???
Thanks in advance...
The logical place to enable/disable controls would be CView::OnUpdate, it is called by the framework after the view's document has been modified and from OnInitialUpdate(); you can also call this function if there is some change that would trigger re-evaluation of your business logic.
EDIT
After reading the question a bit more closely, what you could also do is to post a private message at the end of OnInitialUpdate and "catch" it in your PreTranslateMessage:
PostMessage(WM_APP, 0, 0);
Calling InvalidateRect followed by UpdateWindow against the window in question will mark the entire client area as dirty and force an immediate repaint. Remember that WM_PAINT is not really a message, in the queue in the usual sense, it is pushed out after all other messages have been processed for that window, which would include any invalidations of the area being drawn. No message is generated at all if there are no invalid segments of the active window display.
Does MvvmCross support a cross platform solution for displaying alerts or popups?
Searching the code I found MvxDialogActivityView but it has been commented out. Will this remain the case for now?
If there is no direct support how would you suggest this is best done? (Perhaps the ViewModel would change a property and call FirePropertyChanged so that the View would be aware of it and show an alert.)
Edit 16:04 16th June 2012
What I am trying to do for this specific case is as follows:
On the page a button is clicked, which causes a method to run in the ViewModel which does an evaluation to determine which of two messages should be shown to the customer. The message would be shown as an alert or popup (either native, or preferably totally styled by me). The message would fade after (the click of the OK button, or preferably 3 seconds).
After the message has been dismissed a new page will be navigated too (depending on which of the two messages was shown).
How to handle this definitely depends on what the situation is - there's no single best rule (IMHO)
For a general error display pattern, there's one proposal at http://slodge.blogspot.co.uk/2012/05/one-pattern-for-error-handling-in.html
I've used similar patterns for showing application level notifications - e.g. for when a long running operation completes or when a chat message arrives or...
One interesting post about how to display message boxes was: http://awkwardcoder.blogspot.co.uk/2012/03/showing-message-box-from-viewmodel-in.html - I'm not sure I'd completely follow the end solution, but there are definitely some good points there about what not to do.
For your updated scenario, I would consider using a messenger (like TinyMessenger) or using normal C# events exposed by the ViewModel and consumed by its View
On the page a button is clicked, which causes a method to run in the ViewModel
I would implement this using an ICommand bound to the button Click/Tap/TouchDown
which does an evaluation to determine which of two messages should be shown to the customer.
I would definitely implement the logic within a Service
This would be called from the ViewModel - and the result/decision would probably cause some property or private field state change.
How does the View then decide to show a message? I can think of 3 options:
The View could just respond to a Property change (normal Mvvm INPC) - this would be my preference
The ViewModel could expose a normal C# event which it triggers...
The ViewModel could send a Message
This last option (Messenging) is probably the most flexible solution here - it decouples the View and ViewModel in case you later decide to change responsibilities. To implement messenging, either:
implement your own hub (like I do for errors in http://slodge.blogspot.co.uk/2012/05/one-pattern-for-error-handling-in.html)
or use a generic solution like TinyMessenger
The message would be shown as an alert or popup (either native, or preferably totally styled by me).
This is a View concern - so would be entirely controlled by the View project. I'd use controls like: UIAlert, Toast, ToastPrompt, etc - all of which can be styled
The message would fade after (the click of the OK button, or preferably 3 seconds). After the message has been dismissed...
I'd use some form of Code Behind (or maybe a Behaviour in WP7) in the View. This would detect the click/fade/disappear and would then invoke either an ICommand (my preference) or public method on the ViewModel
a new page will be navigated too
This navigation would be requested from the ViewModel
(depending on which of the two messages was shown).
This would be easy to track through the above flow... presumably the ViewModel already knows what to show.
So that's what I'd do...
it keeps the application flow logic inside the ViewModels (and lower)
it keeps the presentation inside the Views
...but I'm sure there are other options :)
One final note... the fade out and then navigate logic can really get "messed up" by Switching/Tombstoning on WP7 and Android - this may or may not matter for your particular scenario.
I want to able to create reusable user controls within my web app and i'm wondering on how to go about doing so.
Should a user controls properties be
visible to a form that's using it?
What's the best way to go about
loading the controls on the user
control from the form thats using
it? Should there be a public method
within the control that allows you
to load it from an external form or should the user
control be loaded in the page load
event
Is it okay to nest user controls within user controls?
etc...
Thanks for any advice
1) You only need to make properties visible if any page needs to read or modify information on your control. I personally like to keep my user controls as self contained as possible, and keep this to a minimum.
2) I would just rely on the built in page life cycle to render your control, but it is important to note when each of your control's events fire in relation to your pages. You may find that there are times that you need something on your control to render before something on your page does. In this case you will need to rely on the page_init in your control more than the page_load of your control.
3) You technically can nest user controls, but things will get tricky if you need to start reading and writing information (as in your first question) from any of the nested controls. Also, the page life cycle of the nested controls gets even more important. I would avoid this if you can.