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https://github.com/Windows-XAML/Template10.Validation
https://github.com/Windows-XAML/Template10.Validation
Last synced: 1 day ago
JSON representation
- Host: GitHub
- URL: https://github.com/Windows-XAML/Template10.Validation
- Owner: Windows-XAML
- License: mit
- Created: 2016-09-07T22:14:16.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2020-01-02T16:20:45.000Z (almost 5 years ago)
- Last Synced: 2024-08-02T11:14:16.703Z (3 months ago)
- Language: C#
- Size: 1.09 MB
- Stars: 45
- Watchers: 7
- Forks: 9
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-winui - Template10.Validation -   These validation libraries provide UWP developers a comprehensive solution to data validation that solves problems in a realistic and usable way. The associated sample application demonstrates the use and syntax. (Libraries / What We Track)
README
# Validation in Universal Windows Platform
In Windows UWP XAML/C# apps, developers will discover that input controls do not support `DataAnnotation` or `ExceptionValidationRule` or `IDataErrorInfo` or `INotifyDataErrorInfo` or `BindingValidationError`. Even if the platform included these capabilities, there are significant limitations to each that make them a limiting option for application with significant real-world data validation requirements.
## Introducing Template10 Validation
These validation libraries provide UWP developers a comprehensive solution to data validation that solves problems in a realistic and usable way. The associated sample application demonstrates the use and syntax. If you have feedback or a bug to report, do it here: https://github.com/Windows-XAML/Template10/issues.
## Get started
To get started with validation, your models need to inherit `Template10.Validation.ValidatableModelBase`. This will include an implementation of `INotifyPropertyChanged` in case you need it in your logic. Should your poco classes (models) not support inheriting from a new base class, then this validation library will not work for you. The enhancements to your model(s) will include:
### ValidatableModelBase properties
* `public ObservableCollection Errors { get; }`
* `public bool IsDirty { get; }`
* `public bool IsValid { get; }`
* `public ObservableDictionary Properties { get; }`
* `public Action Validator { get; set; }`
### ValidatableModelBase methods
* `public void MarkAsClean();`
* `public void RaisePropertyChanged([CallerMemberName] string propertyName = null);`
* `public void Revert();`
* `public bool Validate();`
* `protected T Read([CallerMemberName] string propertyName = null);`
* `protected void Write(T value, [CallerMemberName] string propertyName = null, bool validateAfter = true);`
In addition to inheriting from `ValidatableModelBase`, both the setter and getters of your model properties will need to change to the following syntax in order to take part in the underlying change tracking mechanism.
#### Your model before
```csharp
public class User
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public override string ToString() => $"{FirstName} {LastName}";
}
```
#### Your model after
```csharp
public class User : Template10.Validation.ValidatableModelBase
{
public int Id { get; set; }
public string FirstName { get { return Read(); } set { Write(value); } }
public string LastName { get { return Read(); } set { Write(value); } }
public override string ToString() => $"{FirstName} {LastName}";
}
```
## Adding validation logic
Once you have implemented these changes, you need to set the `Validator` property of your model - typically when they are created or just before they are exposed in your view-model. (Note: It is not required that you use the MVVP design pattern to use this library - but if you don't you're probably building your app all wrong). You would set your validator something like this:
```csharp
var user = new User
{
FirstName = "Jerry",
LastName = "Nixon",
Validator = i =>
{
var u = i as User;
if (string.IsNullOrEmpty(u.FirstName))
{
u.Properties[nameof(u.FirstName)].Errors.Add("First name is required");
}
if (string.IsNullOrEmpty(u.LastName))
{
u.Properties[nameof(u.LastName)].Errors.Add("Last name is required");
}
},
};
```
Notice in the code above how you are adding one or more errors to the `Errors` property of the model's property; you are not adding to the `Errors` property of the model. This allows errors on a field level. Property errors are automatically propagated to the model-level property `Errors`. Any changes to that list will be overwritten.
## Calling validation logic
Once the validation logic is injected into the model, you can call the model's `Validate()` method to assess the current state of the model. You can repeatedly call `Validate()` as the workflow in your app requires. If the validation logic has significant cost, calling `Validate()` too frequently could have a performance cost to your app.
## New properties of your properties
Above you saw how each property has an `Errors` property. In addition, there is a `Value` property and these others:
### Properties
* `ObservableCollection Errors { get; }`
* `bool IsDirty { get; }`
* `bool IsOriginalSet { get; }`
* `bool IsValid { get; }`
* `T Value { get; set; }`
* `T OriginalValue { get; set; }`
### Event(s)
* `event EventHandler ValueChanged;`
### Methods
* `void MarkAsClean();`
* `void Revert();`
## Error indicator
You will see that most of these properties are managed automatically by the base class. Calling `MarkAsClean()` or `Revert()` impacts `IsDirty` and `Value` respectively. That being said, you can also use them in tandem with the control wrapper that ships in the library. You would use it like this:
```xaml
```
By default the visual looks like this:
## Customized error indicator
The visual definition of the wrapper is defined in the library (https://github.com/Windows-XAML/Template10.Validation/blob/master/Library/Themes/Generic.xaml) and you can override it simply by changing the `Template` property of the wrapper. Here's how you might do it:
```xaml
```
In the XAML above the `ControlTemplate` is created in-line, but could easily be moved to a resource and re-used in multiple controls. It also demonstrates how every control *could* have a separate look, if desired. The XAML above would render a look something like this:
I realize that's a silly use of the control, but it demonstrates an easy starting place.
I hope you enjoy Template 10 Validation!