return message in linq - mysql

Question

how to return a message in linq? please see my code below. my return type is list. please help me.
public List<Product> GetProductsByProductName(string storeId, string productName)
{
Authenticate();
int _storeId = Convert.ToInt32(storeId);
string message = "Item is not added to cart";
var _products = (from p in context.products.AsEnumerable()
where p.StoreId == _storeId && p.ProductName.Contains(productName) && p.ProductIsAvailable.Equals(true)
orderby p.ProductName
select
new Product()
{
ProductName = p.ProductName,
CategoryID = p.CategoryId,
QuantityPerUnit = p.ProductUnit,
UnitPrice = p.ProductPrice,
DiscountValue = p.DiscountValue,
DiscountType = p.DiscountType
}).ToList();
if (_products.Count > 0)
{
return _products;
}
else
{
return message.ToList();
}
}

Answer 1

you should consider throwing an exception.
instead of return meassage.toList try :
throw new Exception("Item is not added to cart");
public List<Product> GetProductsByProductName(string storeId, string productName)
{
...
if (_products.Count > 0)
{
return _products;
}
else
{
throw new Exception( "Item is not added to cart");
}
}
you can handle it outside where you call the GetProductsByProductName method
you can even define your own exception like ItemAddException : Exception ....
or you add a new out bool parameter that tells you if it worked, or an out string parameter for messages :)
public List<Product> GetProductsByProductName(string storeId, string productName, out string message)
{
...
if (_products.Count > 0)
{
return _products;
}
else
{
message = "Item is not added to cart";
return null; //check if caller can handle nulls ;)
}
}
so if the method was called
var l = GetProductsByProductName(storeId, productName);
you will now have to do
string message="";
var l = GetProductsByProductName(string storeId, string productName, out message);
if(String.IsNullOrEmpty(message)==false)
{
.... do stuff
}
or if you use the exception mehtod :
try
{
var l = GetProductsByProductName(storeId, productName);
}
catch(Excepion ex)
{
... do stuff
}