private Expression GetFilterExpression(Operation.Condition cond)
{
if (IsFilter(cond.Constant) && FilterValues != null)
{
var filterProp = cond.Constant.Remove(0, 1);
ViewMappingHelper helper = new ViewMappingHelper(new ViewMappingAttribute(filterProp));
var value = Expression.Lambda(
Expression.Block(
ExpressionHelpers.ParseProperty(LinqToSql, Expression.Constant(FilterValues), FilterValues.GetType(), cond.PropertyExpression.Type, helper, 0, FilterValues, true))).Compile().DynamicInvoke();
if (this.IsTypeSame(cond))
return Expression.Constant(value, cond.PropertyExpression.Type);
return Expression.Constant(value);
}
else if (FilterValues == null && IsFilter(cond.Constant))
throw new NullReferenceException("Filter Object cannot be null if the View Requires it");
Type parameterType;
if (cond.Operator == FilterOperators.Contains)
{
if (cond.PropertyExpression.Type == typeof(String))
parameterType = cond.PropertyExpression.Type;
else
parameterType = cond.PropertyExpression.Type.GetGenericArguments().Single();
}
else
parameterType = cond.PropertyExpression.Type;
Object constant;
if (typeof(Enum).IsAssignableFrom(parameterType))
{
var enumInt = 0;
if (int.TryParse(cond.Constant, out enumInt))
constant = Enum.ToObject(parameterType, enumInt);
else
constant = Enum.Parse(parameterType, cond.Constant);
}
else
constant = cond.Constant;
if (parameterType.IsNullable() && parameterType.IsSimpleType() && parameterType.IsValueType)
return Expression.Constant(constant.ToString().ToNullable(parameterType), parameterType);
else
return Expression.Constant(Convert.ChangeType(constant, parameterType));
}
private IEnumerable<Operation> BuildOperations(String filterString)
{
List<String> stringOperations = filterString.Split(':').ToList();
for (int i = 0; i < stringOperations.Count; i = i + 1)
{
if (stringOperations.Count >= i + 3)
{
Operation opp = new Operation();
if (i > 0)
{
opp.Operator = stringOperations[i++];
}
Type outModel = ViewModel;
var propertyString = stringOperations[i++];
ViewMappingHelper helper = new ViewMappingHelper(new ViewMappingAttribute(propertyString));
opp.Filter.PropertyExpression = ExpressionHelpers.ParseProperty(LinqToSql, ParameterExpression, ViewModel, typeof(Object), helper, 0, null, true);
opp.Filter.Operator = stringOperations[i++];
var constantString = stringOperations[i];
opp.Filter.Constant = constantString;
yield return opp;
}
else
throw new Exception("Invalid Filter");
}
}