I am having a form with different type of controls like Text Box, Drop downs, Check box, Radio buttons etc. All these controls are loaded dynamically from database at run time.
I want to perform validation on Text box on conditional basis. For example, If we have selected any value in drop down, then you must have to fill details in Text box. Otherwise text box details are not required.
I am open to use database to perform this task and I am using MVVM pattern in my project.
Any help on this is highly appreciated.
Thanks.
(I started this as a comment, but it ended up being too long).
In theory you have access to all these controls and their values in your ViewModel.
Without knowing the specifics of your program, it's difficult to suggest anything useful, but in essence you need to expose some more properties from your ViewModel (probably boolean) which will be calculated based on the values in your controls. Then you need to bind IsEnabled properties on your controls to these new properties.
Sounds simple, but I think you have some architectural problems which will make it difficult to implement what I suggested above. In order for this to work and automatically update your controls whenever other controls' content change, your ViewModel needs to implement INotifyPropertyChanged and raise PropertyChanged event every time you update one of those boolean properties.
I think what you're trying to do could be achieved with ItemsControl and DataTemplates (and maybe DataTemplateSelectors). This will allow you to store "data" in your ViewModel (say List or something more specific) without referencing the actual Controls and the relevant DataTemplates will add the right controls for different data types you have in your ViewModel.
Related
In my app, there is a feature to customize it's own Controls (like Textbox, Labels, Textblocks, Buttons, etc), this feature interface is located inside a TabItem. Lets say i want to modify Button A, which is located in ANOTHER container. On the feature interface, i set it's Foreground property to White, at this moment i don't know whether the Button looks better or not, so i have to go to the container which contains that Button.
What am i trying to do is, i want to create a "preview" Control (which is the same type as the actual target) inside the feature interface. I want any changes on this "preview" control are reflected to the actual target Control. With this, i won't need to navigate to where the target Control located.
When i used the title ("How do you bind 2 controls)" with google, all results actually gives me "how to bind SINGLE property of a control to another control's property". What i want is how do you bind/link 2 Controls literally, i mean, i want to bind ALL properties of Control A to ALL properties of Control B.
Binding them one by one is one (tiring) way. Is there another way to achieve this?
I would prefer code-behind method.
There is no "fast" way to do this, you will have to bind one by one according to your buisness logic.
Also a binding is not cheap regarding performance so binding each and every property of a control even those you dont explicitly need, is a warning sign.
My program will prompt the user for a number, i.e. 25. The program will then start the "main form" with 25 controls (textbox). The 25 (or whatever number) of textboxes (or whatever control) will need to be formatted evenly. I will also need to be able to retrieve the text (or another property if I use another control) in order, from left to right and up to down. What is the best method of approaching this?
Using WPF MVVM. In a .XAML file, create a DataTemplate with the DataType of a ViewModel that will provide the binding for your TextBoxs, lets call this the TextboxViewModel. Then using a ItemsControl element with an ItemsSource of TextboxViewModel. You'll be able to instantiate as many TextBoxs as you want and be able to get the result by browsing through your list of TextboxViewModel.
Supposing you are using Windows Forms here.
Dynamically create the X controls and add them to the Controls collection of your form. To ease the access to them you can store their reference in a List and set some event handlers too, depending on your needs. You just need to calculate their positions while you add them.
If WinForms, this is exactly what the FlowLayoutPanel is for. Just add the controls to it and they will arrange themselves automatically, wrapping down to the next row as needed. As Mihai already suggested, you could also keep reference to those controls in a List.
Another option would be to use a TableLayoutPanel. It's a little more difficult to learn and use, but is much more flexible and powerful.
I have a C# CLI program that scans for missing Windows updates and writes them to command line or serializes them to XML depending on the flag passed in. I'm trying to build a WPF component to this but am unsure of a few things. Specifically I'd like to write all missing updates to a grid in the center of my WPF main window. The appearance would be something like this (with gridlines between the fields):
NAME SEVERITY DETECTED
Security Update for Windows 7 (KB1234567) Important 3/9/2014
Security Update for Windows 7 (KB7654321) Critical 3/9/2014
My specific questions:
What type of control would I need to add to the window to house this data?
How do I send the data (detected missing update names and properties) to the grid for display?
How can I set the control so that it is collapsed (or invisible) when no missing updates are detected?
Will I need to add a scrollbar to the grid or will one display automatically?
Apologies for the simple questions. I'm really just looking for some examples to get started, and I haven't been able to find anything thus far that meets my needs.
What type of control would I need to add to the window to house this
data?
DataGrid control is what you are looking for.
How do I send the data (detected missing update names and properties)
to the grid for display?
Bind ItemsSourceof DataGrid to ObservableCollection<T> where T will be class containing data with properties Name, Severity and Detected.
How can I set the control so that it is collapsed (or invisible) when
no missing updates are detected?
Add a DataTrigger to check if ItemsSource collection contains no data, collapse the visibility.
Will I need to add a scrollbar to the grid or will one display
automatically?
DataGrid internally use ScrollViewer. No need to add explicitly.
Refer to the dataGrid samples here and here.
As an alternative DataGrid can offer ListView control, it will be little "easier" than the DataGrid, he also supports the ability to sort columns. For him also need to bind a ItemsSource collection to display:
The ListView control provides the infrastructure to display a set of data items in different layouts or views. For example, a user may want to display data items in a table and also to sort its columns.
Example in MSDN.
Little add some notes to the wonderful answer of #RohitVats, all that has been said about DataGrid also applies to ListView:
How can I set the control so that it is collapsed (or invisible) when no missing updates are detected?
In this situation, I advise you to adhere to the principle of MVVM. Use Binding and Commands to create an independent application. You want to create property (for example IsEnabled) in Model / ViewModel and use bindings to set them in the View, in order to avoid apply directly to the Control. WinForms style app or "regular" applications creates a strong connection between logic and UI, which subsequently impedes further change and application maintenance.
How can I check if any control (check box/radio button) of the currently active form has been selected/toggled?
My goal is to create an option called Save changes automatically which would enable saving the current state of check boxes and radio buttons, so I need to know when any control is selected/toggled (to execute the save settings method). I don't want to create a separate event handler for every control, I'm looking for a generic solution if it is possible.
This is not a job for the user interface.
Use databinding to change a Model in code-behind and let the model trigger/escalate changes.
To help you on your way a little:
Your checkboxes and other controls are not where your data is. They should only show the data.
Create an object (the Model) with boolean properties for the checkboxes and int/enum properties for the radioboxes. Set up the databindings from the controls to the properties.
Then you can implement the necessary logic in the Setters of the properties.
As Henk proposed, you could use a Separation of Concerns pattern such as MVC to separate UI and domain logic. As the user makes changes to some UI widget, you update the value in the model, for example by setting a property. The property setters could then update a IsDirty (or HasChanges, ...) field. This property would be read by the UI which would, depending on the value of IsDirty, decide what needs to be done. (Display a MessageBox("Do you want to save your changes") or something else)
I do think that Henk was thinking web while you tagged the question with WinForms. Chances are you are not using a pattern to separate UI and domain logic. (and that UI and domain code are already so intertwined that your current deadline does not allow you to introduce a model right now)
You could achieve the same thing by placing the IsDirty field on your Form and having the Changed EventHandlers set that IsDirty value. By subclassing the Form (ie put the IsDirty on your 'FormBase') and your controls (for example by introducing a watermark), you could have this behavior out of the box for all your forms.
I've searched around, but don't think I really found an answer. I'm trying to get a handle more on data binding and starting to see things coming together. Can you do data binding to something like "IsEnabled" based on TWO Properties, if so, how...
ex: A Window has some controls... certain controls may or may not be enabled at certain times. Some times it's as simple as when data is available (such as finding a record to edit), or when adding... I would consider this an "Editing" mode of the window. Sometimes, certain controls are only available when doing an Edit AND the user has admin permissions.
BOTH conditions need to be true for the control to be "enabled". Similarly could be applied to visibility of a control under similar conditions.
If you're using the MVVM model (which you really should if you're doing WPF development), then you're thinking about it the wrong way.
This sort of logic belongs in the ViewModel. You should have a single property on the ViewModel that represents the visiblity of the control (or controls) and have whatever logic is required (permissions, data validity, mode, etc.) in the ViewModel to determine this value. Putting the logic on the view hamstrings you and violates SOC.
The ViewModel is supposed to model your view. That is, there should (in most cases) be a 1:1 correlation between elements and concepts in your view (such as whether or not a feature is enabled or visible) and properties on your ViewModel.
You could use MultiBindings and some custom aggregate multi-value converters to achieve this declaratively. Alternatively, it may be more explicit (and therefore recommended) to place an additional property on your view model which compounds the values of the other view model properties.