ViewModelBase
| Name | Value |
|---|---|
| Assembly | Catel.MVVM |
| Namespace | Catel.MVVM |
| Available on | .NET Framework 4.5, .NET Framework 4.6, Xamarin - Android, Xamarin - iOS |
public abstract class ViewModelBase : IUniqueIdentifyable, IRelationalViewModel, ValidatableModelBase
Base types ValidatableModelBase
Implements interfaces IUniqueIdentifyable,IRelationalViewModel
View model base for MVVM implementations. This class is based on the ModelBase, and supports all common interfaces used by WPF.
Remarks
This view model base does not add any services.
Fields
ViewModelManager
Gets the view model manager.
Constructors
ViewModelBase()
Initializes a new instance of the ViewModelBase class.
Exceptions
| Name | Description |
|---|---|
| T:Catel.MVVM.ModelNotRegisteredException | A mapped model is not registered. |
| T:Catel.MVVM.PropertyNotFoundInModelException | A mapped model property is not found. |
ViewModelBase(IServiceLocator serviceLocator, bool supportIEditableObject, bool ignoreMultipleModelsWarning, bool skipViewModelAttributesInitialization)
Initializes a new instance of the ViewModelBase class. This constructor allows the injection of a custom IServiceLocator.
Parameters
| Name | Description |
|---|---|
| serviceLocator | The service locator to inject. Ifnull, the Default will be used. |
| supportIEditableObject | if set totrue, the view model will natively support models that implement the interface. |
| ignoreMultipleModelsWarning | if set totrue, the warning when using multiple models is ignored. |
| skipViewModelAttributesInitialization | if set totrue, the initialization will be skipped and must be done manually via InitializeViewModelAttributes. |
Exceptions
| Name | Description |
|---|---|
| T:Catel.MVVM.ModelNotRegisteredException | A mapped model is not registered. |
| T:Catel.MVVM.PropertyNotFoundInModelException | A mapped model property is not found. |
ViewModelBase(bool supportIEditableObject, bool ignoreMultipleModelsWarning, bool skipViewModelAttributesInitialization)
Initializes a new instance of the ViewModelBase class.
Parameters
| Name | Description |
|---|---|
| supportIEditableObject | if set totrue, the view model will natively support models that implement the interface. |
| ignoreMultipleModelsWarning | if set totrue, the warning when using multiple models is ignored. |
| skipViewModelAttributesInitialization | if set totrue, the initialization will be skipped and must be done manually via InitializeViewModelAttributes. |
Exceptions
| Name | Description |
|---|---|
| T:Catel.MVVM.ModelNotRegisteredException | A mapped model is not registered. |
| T:Catel.MVVM.PropertyNotFoundInModelException | A mapped model property is not found. |
Properties
DeferValidationUntilFirstSaveCall
Gets or sets a value indicating whether all validation should be deferred until the first call to SaveViewModelAsync. If this value istrue, all validation will be suspended. As soon as the first call is made to the SaveViewModelAsync, the validation will no longer be suspended and activated. The default value isfalse.
Remarks
If this value is used, it must be set as first property in the view model because the validation kicks in immediately when properties change.
DependencyResolver
Gets the dependency resolver.
DispatchPropertyChangedEvent
Gets or sets a value indicating whether the AdvancedPropertyChangedEventArgs) will be dispatched using the IDispatcherService. The default value isfalse.
HasErrors
Gets a value indicating whether this object contains any field or business errors.
InvalidateCommandsOnPropertyChanged
Gets or sets a value indicating whether the commands should automatically be invalidated on a property change. If this property isfalse, properties should either be invalidated by the .NET Framework or by a manual call to the Boolean) method.
IsCanceling
Gets a value indicating whether this instance is currently canceling.
IsClosed
Gets a value indicating whether this instance is closed. If a view model is closed, calling CancelViewModelAsync, SaveViewModelAsync or Boolean}) will have no effect.
IsClosing
Gets a value indicating whether this instance is closing.
IsInitialized
Gets a value indicating whether this object is initialized.
IsInitializing
Gets a value indicating whether this object is currently initializing.
IsSaving
Gets a value indicating whether this instance is currently saving.
NavigationContext
Gets the navigation context.
Remarks
Note that the navigation contexts is first available in the OnNavigationCompleted method, not in the constructor.
ParentViewModel
Gets the parent view model.
ThrottlingRate
Gets or sets the throttling rate. When throttling is enabled, the view model will raise property changed event in a timely manner to reduce the number of updates the view has to do based on the properties.
Title
Gets the title of the view model.
UniqueIdentifier
Gets the unique identifier of the view model.
ValidateModelsOnInitialization
Gets or sets a value indicating whether to validate the models as soon as they are initialized. This means that as soon as a model value is set, the view model checks whether the entity already contains errors. If this value istrue, the errors will immediately be returned for mappings on the model. Otherwise, the errors will only become available when a value is entered and then being undone. The default value istrue.
ViewModelCommandManager
Gets the ViewModelCommandManager of this view model.
ViewModelConstructionTime
Gets the view model construction time, which is used to get unique instances of view models.
Events
CanceledAsync
Occurrs when the view model is canceled.
CancelingAsync
Occurs when the view model is about to be canceled.
ClosedAsync
Occurs when the view model has just been closed.
ClosingAsync
Occurs when the view model is being closed.
CommandExecutedAsync
Occurs when a command on the view model has been executed.
InitializedAsync
Occurs when the view model has been initialized.
NavigationCompleted
Occurs when the navigation is completed.
Remarks
This should of course be a cleaner solution, but there is no other way to let a view-model know that navigation has completed. Another option is injection, but this would require every view-model for Windows Phone 7 to accept only the navigation context, which has actually nothing to do with the logic. It is also possible to use the OnNavigationCompleted event.
SavedAsync
Occurs when the view model is saved successfully.
SavingAsync
Occurs when the view model is about to be saved.
Methods
CancelAsync()
Cancels the editing of the data.
Returns
true if successful; otherwisefalse.
CancelViewModelAsync()
Cancels the editing of the data.
Returns
true if successful; otherwisefalse.
CloseAsync()
Closes this instance. Always called after the CancelAsync of SaveAsync method.
CloseViewModelAsync(Nullable<bool> result)
Closes this instance. Always called after the CancelAsync of SaveAsync method.
Parameters
| Name | Description |
|---|---|
| result | The result to pass to the view. This will, for example, be used asDialogResult. |
GetAllModels()
Gets all models that are decorated with the ModelAttribute.
Returns
Array of models.
GetChildViewModels()
Gets the child view models of this view model.
Returns
An enumerable of current child view models.
GetObjectId(IObjectIdGenerator<int> objectIdGenerator)
Gets the object id.
Parameters
| Name | Description |
|---|---|
| objectIdGenerator | The object id generator |
Returns
The object id
GetObjectIdGeneratorType()
Gets the object id generator type.
Returns
The object id generator
InitializeAsync()
Initializes the view model. Normally the initialization is done in the constructor, but sometimes this must be delayed to a state where the associated UI element (user control, window, …) is actually loaded. This method is called as soon as the associated UI element is loaded.
Remarks
It’s not recommended to implement the initialization of properties in this method. The initialization of properties should be done in the constructor. This method should be used to start the retrieval of data from a web service or something similar. During unit tests, it is recommended to manually call this method because there is no external container calling this method.
InitializeModel(string modelProperty, object model)
Called when a model initialized.
Parameters
| Name | Description |
|---|---|
| modelProperty | The name of the model property. |
| model | The model. |
InitializeViewModelAsync()
Initializes the view model. Normally the initialization is done in the constructor, but sometimes this must be delayed to a state where the associated UI element (user control, window, …) is actually loaded. This method is called as soon as the associated UI element is loaded.
Returns
The task.
Remarks
It’s not recommended to implement the initialization of properties in this method. The initialization of properties should be done in the constructor. This method should be used to start the retrieval of data from a web service or something similar. During unit tests, it is recommended to manually call this method because there is no external container calling this method.
InitializeViewModelAttributes()
Initializes the view model attributes, such as the ModelAttribute and ViewModelToModelAttribute. This method is automatically invoked by the constructor. Sometimes, dynamic properties are registered after the constructor. Therefore, it is possible to skip the initialization of the attributes and handle this manually.
Exceptions
| Name | Description |
|---|---|
| T:Catel.MVVM.ModelNotRegisteredException | A mapped model is not registered. |
| T:Catel.MVVM.PropertyNotFoundInModelException | A mapped model property is not found. |
IsModelRegistered(string name)
Determines whether a specific property is registered as a model.
Parameters
| Name | Description |
|---|---|
| name | The name of the registered model. |
Returns
true if a specific property is registered as a model; otherwise,false.
OnClosedAsync(Nullable<bool> result)
Called when the view model has just been closed. This method also raises the ClosedAsync event.
Parameters
| Name | Description |
|---|---|
| result | The result to pass to the view. This will, for example, be used asDialogResult. |
OnClosingAsync()
Called when the view model is about to be closed. This method also raises the ClosingAsync event.
OnModelPropertyChanged(object sender, PropertyChangedEventArgs e)
Called when a property on one of the registered models has changed.
Parameters
| Name | Description |
|---|---|
| sender | The sender. |
| e | The instance containing the event data. |
Remarks
This method will also raise for properties that are not mapped on the view model.
OnNavigationCompleted()
Called when the navigation has completed.
Remarks
This should of course be a cleaner solution, but there is no other way to let a view-model know that navigation has completed. Another option is injection, but this would require every view-model for Windows Phone 7 to accept only the navigation context, which has actually nothing to do with the logic. It is also possible to use the NavigationCompleted event.
OnPropertyChanged(AdvancedPropertyChangedEventArgs e)
Called when a property value has changed.
Parameters
| Name | Description |
|---|---|
| e | The AdvancedPropertyChangedEventArgs instance containing the event data. |
OnValidating(IValidationContext validationContext)
Called when the object is validating.
Parameters
| Name | Description |
|---|---|
| validationContext | The validation context. |
OnValidatingBusinessRules(IValidationContext validationContext)
Called when the object is validating the business rules.
Parameters
| Name | Description |
|---|---|
| validationContext | The validation context. |
OnValidatingFields(IValidationContext validationContext)
Called when the object is validating the fields.
Parameters
| Name | Description |
|---|---|
| validationContext | The validation context. |
RaisePropertyChanged(object sender, AdvancedPropertyChangedEventArgs e)
Raises the PropertyChanged event. This is the one and only method that actually raises the PropertyChanged event. All other methods are (and should be) just overloads that eventually call this method.
Parameters
| Name | Description |
|---|---|
| sender | The sender. |
| e | The instance containing the event data. |
RegisterViewModelServices(IServiceLocator serviceLocator)
Registers the default view model services.
Parameters
| Name | Description |
|---|---|
| serviceLocator | The service locator. |
Exceptions
| Name | Description |
|---|---|
| ArgumentNullException | The serviceLocator isnull. |
ResetModel(string modelProperty, ModelCleanUpMode modelCleanUpMode)
Resets the model by calling uninitializing and initializing the model again. This means that if the model supports, it will be reset.
Parameters
| Name | Description |
|---|---|
| modelProperty | The model property. |
| modelCleanUpMode | The model clean up mode. |
Exceptions
| Name | Description |
|---|---|
| ArgumentNullException | The modelProperty isnull. |
SaveAsync()
Saves the data.
Returns
true if successful; otherwisefalse.
SaveViewModelAsync()
Saves the data.
Returns
true if successful; otherwisefalse.
ToString()
Converts the object to a string.
Returns
System.String.
UninitializeModel(string modelProperty, object model, ModelCleanUpMode modelCleanUpMode)
Called when a model uninitialized.
Parameters
| Name | Description |
|---|---|
| modelProperty | The name of the model property. |
| model | The model. |
| modelCleanUpMode | The model clean up mode. |
UpdateExplicitViewModelToModelMappings()
Updates the view model to model mappings that are defined as Explicit.
UpdateNavigationContext(NavigationContext navigationContext)
Updates the navigation context. The navigation context provided by this class is different from the NavigationContext. Therefore, this method updates the navigation context to match it to the values of the navigationContext.
Parameters
| Name | Description |
|---|---|
| navigationContext | The navigation context. |
Validate(bool force)
Validates the current object for field and business rule errors.
Parameters
| Name | Description |
|---|---|
| force | If set totrue, a validation is forced. When the validation is not forced, it means that when the object is already validated, and no properties have been changed, no validation actually occurs since there is no reason for any values to have changed. |
Remarks
To check whether this object contains any errors, use the ValidationContext property.
Have a question about Catel? Use StackOverflow with the Catel tag!