Need linq query - linq

Question

I have 3 fields(Name, Code, displayNmae) in the list, here I need to get a list as output in which I get all the fields but need to split displayname field by colon and then add list again for each splitted value which is display name.
Hence in output list I will have the 5 row as total display name are 5 in 2 rows.
Need the linq query for this problem.
Name Code displayName
Napkins_tableware - Napkins and tableware - 3_ply:conventional_napkins
hand-towel - Hand and Towel - 2_ply:towel roll:coloured
Output should be like this :
Name Code displayName
Napkins_tableware - Napkins and tableware - 3_ply
Napkins_tableware - Napkins and tableware - conventional_napkin
hand-towel - Hand and Towel - 2_ply
hand-towel - Hand and Towel - towel roll
hand-towel - Hand and Towel - coloured
Solution which I tried in C#
foreach(ProductDetailsWithFilters qs in CategoryProductList())
{
foreach(string friendlyname in qs.displayName.Split(':'))
{
qs.displayName = friendlyname;
tempCategoryProductList.Add(qs);
}
}

Answer 1

If you're translating to LINQ, when you have nested foreach loops those correspond to 'from' clauses in query syntax (or in dot syntax, subsequent ones become SelectMany, see below.) The following should be close to what you want:
var query =
from qs in CategoryProductList()
from friendlyName in qs.displayName.Split(':')
select new ProductDetailsWithFilters(qs.Code, qs.Category, friendlyName);
Note: Because functional programming should be side-effect-free, it's better to select a new instance ProductDetailsWithFilters than it is to modify the existing one in your query. My presumption is that you can call a constructor to build a new one of these.
For you to modify the existing property like your loop implementation does, you would have to iterate over the result -- LINQ doesn't provide such a thing in the framework. Such side-effects often lead to hard-to-find bugs.
To do the equivalent of the above query with a SelectMany and dot-syntax:
var query = CategoryProductList()
.SelectMany(
qs => qs.DisplayName.Split(':'),
(qs, friendlyName) => new ProductDetailsWithFilters(qs.Code, qs.Category, friendlyName));
Both lead to functionally identical code. In this case, I tend to prefer the query-syntax over the dot-syntax partly because because there are several SelectMany overloads and handling the projection involves repeating the variables across both lambda expressions. If you had another "from" to add, the query-syntax hides the management of 'transparent identifiers' that you would otherwise have to deal with in dot-syntax equivalent code. Whatever your preference, you now have both.
It's worth noting that queries are lazy -- they do nothing until you iterate over their result. So it's really what you do with the result from here that is the interesting part - store it .ToList(), directly data-bind it to a UI, use it to service a web-API, etc...