private Expression BuildBaseExpression(ParameterExpression parameter, FilterDescriptor filterDescriptor)
{
var leftSide = GetPropertyExpression(parameter, filterDescriptor.PropertyName);
var underlyingType = Nullable.GetUnderlyingType(leftSide.Type);
if (IsNullableType(underlyingType, filterDescriptor))
{
var hasValue = Expression.Property(leftSide, HasValueProperty);
var value = Expression.Property(leftSide, ValueProperty);
var equality = Expression.Equal(value, GetConstantValueExpression(filterDescriptor.Value, underlyingType));
return(Expression.AndAlso(hasValue, equality));
}
var right = GetConstantValueExpression(filterDescriptor.Value, leftSide.Type);
return(Expression.Equal(leftSide, right));
}
private Expression BuildCollectionExpression(FilterDescriptor filterDescriptor, ParameterExpression parameterExpression)
{
var separatorIndex = filterDescriptor.PropertyName.IndexOf(PropertySeparator, StringComparison.Ordinal);
var collectionProperty = filterDescriptor.PropertyName.Substring(0, separatorIndex);
var propertyName = filterDescriptor.PropertyName.Substring(separatorIndex + 1);
var propertyType = GetCollectionGenericType(parameterExpression, collectionProperty);
var listParameter = Expression.Parameter(propertyType, CollectionParameterName);
var lambda =
Expression.Lambda(
BuildPropertyExpression(
new FilterDescriptor {
PropertyName = propertyName, Value = filterDescriptor.Value
},
listParameter),
listParameter);
var propertyExpression = GetPropertyExpression(parameterExpression, collectionProperty);
var anyExpression = BuildAnyExpression(propertyType, propertyExpression, lambda);
return(AddNullCheck(parameterExpression, filterDescriptor.PropertyName, anyExpression));
}
private static bool FilterProvided(FilterDescriptor filterDescriptor)
{
return(filterDescriptor != null);
}
public ICollection <TClass> ApplyFilter <TClass>(ICollection <TClass> collection, FilterDescriptor filterDescriptor)
{
if (!CollectionHasValues(collection))
{
return(collection);
}
if (!FilterProvided(filterDescriptor))
{
return(collection);
}
MatchPropertyProvided <TClass>(filterDescriptor.PropertyName);
if (!PropertyMatched())
{
return(collection);
}
filterDescriptor.PropertyName = PropertyName;
var expression = _expressionBuilder.GetFilterExpression <TClass>(filterDescriptor);
return(collection.Where(expression.Compile()).ToList());
}
private bool IsNullableType(Type underlyingType, FilterDescriptor filterDescriptor)
{
return(underlyingType != null && filterDescriptor.Value != null);
}
private Expression BuildPropertyExpression(FilterDescriptor filterDescriptor, ParameterExpression parameterExpression)
{
var propertyExpression = BuildBaseExpression(parameterExpression, filterDescriptor);
return(AddNullCheck(parameterExpression, filterDescriptor.PropertyName, propertyExpression));
}
