WPF Validation with Data Annotations - wpf

Question

Hi am struggling with validation with data annotations in WPF
I have a class in a separate project because we are reusing the class across multiple projects.Several of the fields have data annotations for validation.
the validation class combines the errors returned from data annotations with some custom business rules which are different per client
internal class Validation<T> : ValidationRule where T : class, ICore
{
IUnitofWork unitofWork;
List<Func<T, bool>> CompiledRules = new List<Func<T, bool>>();
List<Rule<T>> Rules = new List<Rule<T>>();
Dictionary<string, List<string>> _errors = new Dictionary<string, List<string>>();
List<Func<Object, bool>> FieldRules = new List<Func<object, bool>>();
public Validation()
{
unitofWork = new UnitOfWork();
CompileRules();
}
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
return IsValid((T)value);
}
public ValidationResult Validate(object value,string PropertyName ,CultureInfo cultureInfo)
{
return IsValid((T)value,PropertyName);
}
void CompileRules()
{
Type t = typeof(T);
List<BusinessRule> rules = unitofWork.Repository<BusinessRule>().GetAll(b => b.Name == t.Name && b.Enabled == true);
foreach (BusinessRule b in rules)
{
Func<T, bool> CompiledRule = CompileRule(b);
CompiledRules.Add(CompiledRule);
Rule<T> rule = new Rule<T>();
rule.CompiledRule = CompiledRule;
rule.ErrorMessage = b.MessageTemplate;
rule.FieldName = b.Field;
Rules.Add(rule);
}
}
ValidationResult IsValid(T Value)
{
bool valid = true;
_errors.Clear();
if (CompiledRules.Count > 0 || Value.Errors.Count > 0)
{
//valid = CompiledRules.All(rule => rule(Value));
foreach (Rule<T> r in Rules)
{
bool isValid = r.CompiledRule(Value);
r.PassedRule = isValid;
string field = r.FieldName;
if (!isValid )
{
valid = false;
string ErrorMessage = string.Format("{0} {1}", r.FieldName, r.ErrorMessage);
if (_errors.ContainsKey(field))
_errors[field].Add(ErrorMessage);
else
{
List<string> el = new List<string>();
el.Add(ErrorMessage);
_errors.Add(field, el);
}
}
}
}
ValidateAnnotations(Value,ref valid);
return new ValidationResult(valid, _errors);
}
void ValidateAnnotations(object Value,ref bool Valid)
{
DataAnnotationValidator annotationValidator = new DataAnnotationValidator();
List< System.ComponentModel.DataAnnotations.ValidationResult> results = annotationValidator.ValidateObject(Value);
if (results.Count > 0)
{
Valid = false;
foreach (System.ComponentModel.DataAnnotations.ValidationResult r in results)
{
if (_errors.ContainsKey(r.MemberNames.First()))
{
_errors[r.MemberNames.First()].Add(r.ErrorMessage);
}
else
{
List<string> propErrors = new List<string>();
propErrors.Add(r.ErrorMessage);
_errors.Add(r.MemberNames.First(), propErrors);
}
}
}
}
void ValidateAnnotations(object Value,string PropertyName, ref bool Valid)
{
DataAnnotationValidator annotationValidator = new DataAnnotationValidator();
List<System.ComponentModel.DataAnnotations.ValidationResult> results = annotationValidator.ValidateObject(Value, PropertyName);
if (results.Count > 0)
{
Valid = false;
foreach (System.ComponentModel.DataAnnotations.ValidationResult r in results)
{
if (_errors.ContainsKey(r.MemberNames.First()))
{
_errors[r.MemberNames.First()].Add(r.ErrorMessage);
}
else
{
List<string> propErrors = new List<string>();
propErrors.Add(r.ErrorMessage);
_errors.Add(r.MemberNames.First(), propErrors);
}
}
}
}
ValidationResult IsValid(T Value, string PropertyName)
{
_errors.Remove(PropertyName);
bool valid = true;
if (CompiledRules.Count > 0)
{
//valid = CompiledRules.All(rule => rule(Value));
foreach (Rule<T> r in Rules.Where(b=>b.FieldName == PropertyName))
{
bool isValid = r.CompiledRule(Value);
r.PassedRule = isValid;
string field = r.FieldName;
// string field = "SelectedRow." + r.FieldName;
if (!isValid)
{
valid = false;
string ErrorMessage = string.Format("{0} {1}", r.FieldName, r.ErrorMessage);
if (_errors.ContainsKey(field))
_errors[field].Add(ErrorMessage);
else
{
List<string> el = new List<string>();
el.Add(ErrorMessage);
_errors.Add(field, el);
}
}
}
}
ValidateAnnotations(Value,PropertyName, ref valid);
return new ValidationResult(valid, _errors);
}
public Func<T, bool> CompileRule(BusinessRule r)
{
var paramT = Expression.Parameter(typeof(T));
Expression expression = BuildExpr(r, paramT);
return Expression.Lambda<Func<T, bool>>(expression, paramT).Compile();
}
static Expression BuildExpr(BusinessRule r, ParameterExpression param)
{
var left = MemberExpression.Property(param, r.Field);
var tProp = typeof(T).GetProperty(r.Field).PropertyType;
ExpressionType tBinary;
// is the operator a known .NET operator?
if (ExpressionType.TryParse(r.Operator, out tBinary))
{
var right = Expression.Constant(Convert.ChangeType(r.CompareValue, tProp));
// use a binary operation, e.g. 'Equal' -> 'u.Age == 15'
return Expression.MakeBinary(tBinary, left, right);
}
else
{
var method = tProp.GetMethod(r.Operator);
var tParam = method.GetParameters()[0].ParameterType;
var right = Expression.Constant(Convert.ChangeType(r.CompareValue, tParam));
// use a method call, e.g. 'Contains' -> 'u.Tags.Contains(some_tag)'
return Expression.Call(left, method, right);
}
}
}
internal class Rule<T> where T : class, ICore
{
public string FieldName
{ get;set; }
public Func<T, bool> CompiledRule
{ get; set; }
public Func<object,bool> RevisedRule
{ get; set; }
public string ErrorMessage
{ get; set; }
public bool PassedRule
{ get; set; }
}
internal class Error
{
public string ErrorMessage { get; set; }
public string FieldName { get; set; }
}
The is working as the _errors list has the field names and any errors associated with them.
once we have these we loop through and raise the onPropertyErrorsChangedEvent
internal void SetErrorDetails(ValidationResult Result)
{
propErrors = (Dictionary<string, List<string>>)Result.ErrorContent;
foreach (string key in propErrors.Keys)
{
OnPropertyErrorsChanged(key);
}
}
on my view the 2 fields are
<TextBox Canvas.Left="138"
Canvas.Top="75"
FontFamily="Verdana"
HorizontalAlignment="Left"
Height="20"
Text="{Binding OrganizationName,ValidatesOnDataErrors=True,NotifyOnValidationError=True,ValidatesOnNotifyDataErrors=True,ValidatesOnExceptions=True}" VerticalAlignment="Top" Width="137"
Validation.ErrorTemplate="{StaticResource ValidationTemplate }"
Style="{StaticResource TextErrorStyle}"/>
<TextBox Canvas.Left="138"
Canvas.Top="225"
FontFamily="Verdana"
HorizontalAlignment="Left"
Height="20"
Text="{Binding SelectedRow.Postcode,ValidatesOnDataErrors=True,ValidatesOnNotifyDataErrors=True,ValidatesOnExceptions=True}"
VerticalAlignment="Top"
Width="137"
Validation.ErrorTemplate="{StaticResource ValidationTemplate }"
Style="{StaticResource TextErrorStyle}" />
I am encountering 2 problems i am encountering
When bound directly to the selectedrow (Postcode) my data annotations appear when the form is loaded but when bound via a field on my view model (Organisation Name) they do not . We need to bind these to fields on the view model so that the business rules get run as part of validation.
Second problem if i save the form with an invalid entry for the organisation the save stops because it is invalid however i don't get an error notification even though there is an error for the property in the _errors.
I am not sure what i am doing wrong could someone point me in the right direction please?
[Edit]
We use a third party document service to create and show the view
void CreateDocument(object Arg)
{
string title = string.Empty;
if (Arg.ToString().ToLower() == "edit" && SelectedRow !=null)
{
if (SelectedRow.OrganizationName != null)
title = SelectedRow.OrganizationName;
}
else
{
SelectedRow = new Address();
title = "New Address";
}
AddressDetailVM detail = new AddressDetailVM(SelectedRow,this);
Document = iInternal.CreateDocument("AddressDetails",
detail,
title
);
detail.Document = Document;
// Document = iInternal.CreateDocument("AddressDetails", null, this, title);
Document.Show();
}