Class ObservableValidator

Namespace

CommunityToolkit.Mvvm.ComponentModel

Assembly

CommunityToolkit.Mvvm.dll

A base class for objects implementing the INotifyDataErrorInfo interface. This class also inherits from ObservableObject, so it can be used for observable items too.

public abstract class ObservableValidator : ObservableObject, INotifyPropertyChanged, INotifyPropertyChanging, INotifyDataErrorInfo

Inheritance

object

ObservableObject

ObservableValidator

Implements

INotifyPropertyChanged

INotifyPropertyChanging

INotifyDataErrorInfo

Inherited Members

ObservableObject.OnPropertyChanged(PropertyChangedEventArgs)

ObservableObject.OnPropertyChanging(PropertyChangingEventArgs)

ObservableObject.OnPropertyChanged(string)

ObservableObject.OnPropertyChanging(string)

ObservableObject.SetProperty<T>(ref T, T, string)

ObservableObject.SetProperty<T>(ref T, T, IEqualityComparer<T>, string)

ObservableObject.SetProperty<T>(T, T, Action<T>, string)

ObservableObject.SetProperty<T>(T, T, IEqualityComparer<T>, Action<T>, string)

ObservableObject.SetProperty<TModel, T>(T, T, TModel, Action<TModel, T>, string)

ObservableObject.SetProperty<TModel, T>(T, T, IEqualityComparer<T>, TModel, Action<TModel, T>, string)

ObservableObject.SetPropertyAndNotifyOnCompletion(ref ObservableObject.TaskNotifier, Task, string)

ObservableObject.SetPropertyAndNotifyOnCompletion(ref ObservableObject.TaskNotifier, Task, Action<Task>, string)

ObservableObject.SetPropertyAndNotifyOnCompletion<T>(ref ObservableObject.TaskNotifier<T>, Task<T>, string)

ObservableObject.SetPropertyAndNotifyOnCompletion<T>(ref ObservableObject.TaskNotifier<T>, Task<T>, Action<Task<T>>, string)

ObservableObject.PropertyChanged

ObservableObject.PropertyChanging

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Constructors

ObservableValidator()

Initializes a new instance of the ObservableValidator class. This constructor will create a new ValidationContext that will be used to validate all properties, which will reference the current instance and no additional services or validation properties and settings.

protected ObservableValidator()

ObservableValidator(IDictionary<object, object?>?)

Initializes a new instance of the ObservableValidator class. This constructor will create a new ValidationContext that will be used to validate all properties, which will reference the current instance.

protected ObservableValidator(IDictionary<object, object?>? items)

Parameters

items IDictionary<object, object>

A set of key/value pairs to make available to consumers.

ObservableValidator(ValidationContext)

Initializes a new instance of the ObservableValidator class. This constructor will store the input ValidationContext instance, and it will use it to validate all properties for the current viewmodel.

protected ObservableValidator(ValidationContext validationContext)

Parameters

validationContext ValidationContext

The ValidationContext instance to use to validate properties.

This instance will be passed to all TryValidateObject(object, ValidationContext, ICollection<ValidationResult>) calls executed by the current viewmodel, and its MemberName property will be updated every time before the call is made to set the name of the property being validated. The property name will not be reset after that, so the value of MemberName will always indicate the name of the last property that was validated, if any.

Exceptions

ArgumentNullException

Thrown if validationContext is null.

ObservableValidator(IServiceProvider?, IDictionary<object, object?>?)

Initializes a new instance of the ObservableValidator class. This constructor will create a new ValidationContext that will be used to validate all properties, which will reference the current instance.

protected ObservableValidator(IServiceProvider? serviceProvider, IDictionary<object, object?>? items)

Parameters

serviceProvider IServiceProvider

An IServiceProvider instance to make available during validation.

items IDictionary<object, object>

A set of key/value pairs to make available to consumers.

Properties

HasErrors

public bool HasErrors { get; }

Property Value

bool

Methods

ClearErrors(string?)

Clears the validation errors for a specified property or for the entire entity.

protected void ClearErrors(string? propertyName = null)

Parameters

propertyName string

The name of the property to clear validation errors for. If a null or empty name is used, all entity-level errors will be cleared.

GetErrors(string?)

public IEnumerable<ValidationResult> GetErrors(string? propertyName = null)

Parameters

propertyName string

Returns

IEnumerable<ValidationResult>

SetProperty<T>(T, T, Action<T>, bool, string)

Compares the current and new values for a given property. If the value has changed, raises the PropertyChanging event, updates the property with the new value, then raises the PropertyChanged event. Similarly to the SetProperty<T>(T, T, Action<T>, string?) method, this overload should only be used when SetProperty<T>(ref T, T, string?) can't be used directly.

protected bool SetProperty<T>(T oldValue, T newValue, Action<T> callback, bool validate, string propertyName = null)

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

callback Action<T>

A callback to invoke to update the property value.

validate bool

If true, newValue will also be validated.

propertyName string

(optional) The name of the property that changed.

Returns

bool

true if the property was changed, false otherwise.

Type Parameters

T

The type of the property that changed.

Remarks

This method is just like SetProperty<T>(T, T, Action<T>, string?), just with the addition of the validate parameter. As such, following the behavior of the base method, the PropertyChanging and PropertyChanged events are not raised if the current and new value for the target property are the same.

Exceptions

ArgumentNullException

Thrown if callback or propertyName are null.

SetProperty<T>(T, T, IEqualityComparer<T>, Action<T>, bool, string)

Compares the current and new values for a given property. If the value has changed, raises the PropertyChanging event, updates the property with the new value, then raises the PropertyChanged event. See additional notes about this overload in SetProperty<T>(T, T, Action<T>, bool, string).

protected bool SetProperty<T>(T oldValue, T newValue, IEqualityComparer<T> comparer, Action<T> callback, bool validate, string propertyName = null)

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

comparer IEqualityComparer<T>

The IEqualityComparer<T> instance to use to compare the input values.

callback Action<T>

A callback to invoke to update the property value.

validate bool

If true, newValue will also be validated.

propertyName string

(optional) The name of the property that changed.

Returns

bool

true if the property was changed, false otherwise.

Type Parameters

T

The type of the property that changed.

Exceptions

ArgumentNullException

Thrown if comparer, callback or propertyName are null.

SetProperty<T>(ref T, T, bool, string)

Compares the current and new values for a given property. If the value has changed, raises the PropertyChanging event, updates the property with the new value, then raises the PropertyChanged event.

protected bool SetProperty<T>(ref T field, T newValue, bool validate, string propertyName = null)

Parameters

field T

The field storing the property's value.

newValue T

The property's value after the change occurred.

validate bool

If true, newValue will also be validated.

propertyName string

(optional) The name of the property that changed.

Returns

bool

true if the property was changed, false otherwise.

Type Parameters

T

The type of the property that changed.

Remarks

This method is just like SetProperty<T>(ref T, T, string?), just with the addition of the validate parameter. If that is set to true, the new value will be validated and ErrorsChanged will be raised if needed. Following the behavior of the base method, the PropertyChanging and PropertyChanged events are not raised if the current and new value for the target property are the same.

Exceptions

ArgumentNullException

Thrown if propertyName is null.

SetProperty<T>(ref T, T, IEqualityComparer<T>, bool, string)

Compares the current and new values for a given property. If the value has changed, raises the PropertyChanging event, updates the property with the new value, then raises the PropertyChanged event. See additional notes about this overload in SetProperty<T>(ref T, T, bool, string).

protected bool SetProperty<T>(ref T field, T newValue, IEqualityComparer<T> comparer, bool validate, string propertyName = null)

Parameters

field T

The field storing the property's value.

newValue T

The property's value after the change occurred.

comparer IEqualityComparer<T>

The IEqualityComparer<T> instance to use to compare the input values.

validate bool

If true, newValue will also be validated.

propertyName string

(optional) The name of the property that changed.

Returns

bool

true if the property was changed, false otherwise.

Type Parameters

T

The type of the property that changed.

Exceptions

ArgumentNullException

Thrown if comparer or propertyName are null.

SetProperty<TModel, T>(T, T, IEqualityComparer<T>, TModel, Action<TModel, T>, bool, string)

Compares the current and new values for a given nested property. If the value has changed, raises the PropertyChanging event, updates the property and then raises the PropertyChanged event. The behavior mirrors that of SetProperty<TModel, T>(T, T, IEqualityComparer<T>, TModel, Action<TModel, T>, string?), with the difference being that this method is used to relay properties from a wrapped model in the current instance. For more info, see the docs for SetProperty<TModel, T>(T, T, IEqualityComparer<T>, TModel, Action<TModel, T>, string?).

protected bool SetProperty<TModel, T>(T oldValue, T newValue, IEqualityComparer<T> comparer, TModel model, Action<TModel, T> callback, bool validate, string propertyName = null) where TModel : class

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

comparer IEqualityComparer<T>

The IEqualityComparer<T> instance to use to compare the input values.

model TModel

The model

callback Action<TModel, T>

The callback to invoke to set the target property value, if a change has occurred.

validate bool

If true, newValue will also be validated.

propertyName string

(optional) The name of the property that changed.

Returns

bool

true if the property was changed, false otherwise.

Type Parameters

TModel

The type of model whose property (or field) to set.

T

The type of property (or field) to set.

Exceptions

ArgumentNullException

Thrown if comparer, model, callback or propertyName are null.

SetProperty<TModel, T>(T, T, TModel, Action<TModel, T>, bool, string)

Compares the current and new values for a given nested property. If the value has changed, raises the PropertyChanging event, updates the property and then raises the PropertyChanged event. The behavior mirrors that of SetProperty<TModel, T>(T, T, TModel, Action<TModel, T>, string?), with the difference being that this method is used to relay properties from a wrapped model in the current instance. For more info, see the docs for SetProperty<TModel, T>(T, T, TModel, Action<TModel, T>, string?).

protected bool SetProperty<TModel, T>(T oldValue, T newValue, TModel model, Action<TModel, T> callback, bool validate, string propertyName = null) where TModel : class

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

model TModel

The model

callback Action<TModel, T>

The callback to invoke to set the target property value, if a change has occurred.

validate bool

If true, newValue will also be validated.

propertyName string

(optional) The name of the property that changed.

Returns

bool

true if the property was changed, false otherwise.

Type Parameters

TModel

The type of model whose property (or field) to set.

T

The type of property (or field) to set.

Exceptions

ArgumentNullException

Thrown if model, callback or propertyName are null.

TrySetProperty<T>(T, T, Action<T>, out IReadOnlyCollection<ValidationResult>, string)

Tries to validate a new value for a specified property. If the validation is successful, SetProperty<T>(T, T, Action<T>, string?) is called, otherwise no state change is performed.

protected bool TrySetProperty<T>(T oldValue, T newValue, Action<T> callback, out IReadOnlyCollection<ValidationResult> errors, string propertyName = null)

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

callback Action<T>

A callback to invoke to update the property value.

errors IReadOnlyCollection<ValidationResult>

The resulting validation errors, if any.

propertyName string

(optional) The name of the property that changed.

Returns

bool

Whether the validation was successful and the property value changed as well.

Type Parameters

T

The type of the property that changed.

Exceptions

ArgumentNullException

Thrown if callback or propertyName are null.

TrySetProperty<T>(T, T, IEqualityComparer<T>, Action<T>, out IReadOnlyCollection<ValidationResult>, string)

Tries to validate a new value for a specified property. If the validation is successful, SetProperty<T>(T, T, IEqualityComparer<T>, Action<T>, string?) is called, otherwise no state change is performed.

protected bool TrySetProperty<T>(T oldValue, T newValue, IEqualityComparer<T> comparer, Action<T> callback, out IReadOnlyCollection<ValidationResult> errors, string propertyName = null)

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

comparer IEqualityComparer<T>

The IEqualityComparer<T> instance to use to compare the input values.

callback Action<T>

A callback to invoke to update the property value.

errors IReadOnlyCollection<ValidationResult>

The resulting validation errors, if any.

propertyName string

(optional) The name of the property that changed.

Returns

bool

Whether the validation was successful and the property value changed as well.

Type Parameters

T

The type of the property that changed.

Exceptions

ArgumentNullException

Thrown if comparer, callback or propertyName are null.

TrySetProperty<T>(ref T, T, IEqualityComparer<T>, out IReadOnlyCollection<ValidationResult>, string)

Tries to validate a new value for a specified property. If the validation is successful, SetProperty<T>(ref T, T, IEqualityComparer<T>, string?) is called, otherwise no state change is performed.

protected bool TrySetProperty<T>(ref T field, T newValue, IEqualityComparer<T> comparer, out IReadOnlyCollection<ValidationResult> errors, string propertyName = null)

Parameters

field T

The field storing the property's value.

newValue T

The property's value after the change occurred.

comparer IEqualityComparer<T>

The IEqualityComparer<T> instance to use to compare the input values.

errors IReadOnlyCollection<ValidationResult>

The resulting validation errors, if any.

propertyName string

(optional) The name of the property that changed.

Returns

bool

Whether the validation was successful and the property value changed as well.

Type Parameters

T

The type of the property that changed.

Exceptions

ArgumentNullException

Thrown if comparer or propertyName are null.

TrySetProperty<T>(ref T, T, out IReadOnlyCollection<ValidationResult>, string)

Tries to validate a new value for a specified property. If the validation is successful, SetProperty<T>(ref T, T, string?) is called, otherwise no state change is performed.

protected bool TrySetProperty<T>(ref T field, T newValue, out IReadOnlyCollection<ValidationResult> errors, string propertyName = null)

Parameters

field T

The field storing the property's value.

newValue T

The property's value after the change occurred.

errors IReadOnlyCollection<ValidationResult>

The resulting validation errors, if any.

propertyName string

(optional) The name of the property that changed.

Returns

bool

Whether the validation was successful and the property value changed as well.

Type Parameters

T

The type of the property that changed.

Exceptions

ArgumentNullException

Thrown if propertyName is null.

TrySetProperty<TModel, T>(T, T, IEqualityComparer<T>, TModel, Action<TModel, T>, out IReadOnlyCollection<ValidationResult>, string)

Tries to validate a new value for a specified property. If the validation is successful, SetProperty<TModel, T>(T, T, IEqualityComparer<T>, TModel, Action<TModel, T>, string?) is called, otherwise no state change is performed.

protected bool TrySetProperty<TModel, T>(T oldValue, T newValue, IEqualityComparer<T> comparer, TModel model, Action<TModel, T> callback, out IReadOnlyCollection<ValidationResult> errors, string propertyName = null) where TModel : class

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

comparer IEqualityComparer<T>

The IEqualityComparer<T> instance to use to compare the input values.

model TModel

The model

callback Action<TModel, T>

The callback to invoke to set the target property value, if a change has occurred.

errors IReadOnlyCollection<ValidationResult>

The resulting validation errors, if any.

propertyName string

(optional) The name of the property that changed.

Returns

bool

Whether the validation was successful and the property value changed as well.

Type Parameters

TModel

The type of model whose property (or field) to set.

T

The type of property (or field) to set.

Exceptions

ArgumentNullException

Thrown if comparer, model, callback or propertyName are null.

TrySetProperty<TModel, T>(T, T, TModel, Action<TModel, T>, out IReadOnlyCollection<ValidationResult>, string)

Tries to validate a new value for a specified property. If the validation is successful, SetProperty<TModel, T>(T, T, TModel, Action<TModel, T>, string?) is called, otherwise no state change is performed.

protected bool TrySetProperty<TModel, T>(T oldValue, T newValue, TModel model, Action<TModel, T> callback, out IReadOnlyCollection<ValidationResult> errors, string propertyName = null) where TModel : class

Parameters

oldValue T

The current property value.

newValue T

The property's value after the change occurred.

model TModel

The model

callback Action<TModel, T>

The callback to invoke to set the target property value, if a change has occurred.

errors IReadOnlyCollection<ValidationResult>

The resulting validation errors, if any.

propertyName string

(optional) The name of the property that changed.

Returns

bool

Whether the validation was successful and the property value changed as well.

Type Parameters

TModel

The type of model whose property (or field) to set.

T

The type of property (or field) to set.

Exceptions

ArgumentNullException

Thrown if model, callback or propertyName are null.

ValidateAllProperties()

Validates all the properties in the current instance and updates all the tracked errors. If any changes are detected, the ErrorsChanged event will be raised.

protected void ValidateAllProperties()

Remarks

Only public instance properties (excluding custom indexers) that have at least one ValidationAttribute applied to them will be validated. All other members in the current instance will be ignored. None of the processed properties will be modified - they will only be used to retrieve their values and validate them.

ValidateProperty(object?, string)

Validates a property with a specified name and a given input value. If any changes are detected, the ErrorsChanged event will be raised.

protected void ValidateProperty(object? value, string propertyName = null)

Parameters

value object

The value to test for the specified property.

propertyName string

The name of the property to validate.

Exceptions

ArgumentNullException

Thrown when propertyName is null.

Events

ErrorsChanged

public event EventHandler<DataErrorsChangedEventArgs>? ErrorsChanged

Event Type

EventHandler<DataErrorsChangedEventArgs>