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How to convert list of lists to single list in c# using lambda expression?

Description:I have records coming from database where each item can have multiple TagIds(List<string>) assigned to it. I have combined the lists but currently it has become a list of lists as shown below,

List<List<string>> listOfLists=databaseQueriedItems;

but I need the items in one list like following one(i.e I want to flatten the hierarchy)

List<string> singleListOfStrings;

Posted by: | Posted on: Aug 29, 2020

1 answers



This can be easily handled in one line of code by using the SelectMany method as shown below.

List<string> singleListOfStrings= databaseQueriedItems.SelectMany(dqi => dqi.TagIds).ToList()

Replied by: | Replied on: Aug 29, 2020