How do I print the contents of my list into a text file?

Question

I have restaurant data and I am trying to analyze who visited a particular Restaurant X. The data has this structure:

public class RestaurantXPatrons
{
    public String PatronName { get; set;}
    public List <strings> DateofVisits = new List <strings>();
}

I created a List of RestaurantXPatrons called lstX, and I want to output lstX to a tab-delimited text file (for viewing in Excel at a later time). So here's my output code:

var output = lstX.Select ( x => x.PatronName + "\t" + x.DateofVisits );
string filepath = @"C:\data.txt";
System.IO.File.WriteAllLines(filepath, output);

When I view the results in Excel or Notepad, I see "System.Collections.Generic.List`1[System.String] " where there should be the contents of the DateofVisits list for each Patron of Restaurant X. My question is, how do I get the contents of the list into my output?

Answer 1

You need to either do something like x.DateOfVisits.FirstOrDefault() (to get the first instance) or flatten the list to string like: String.Join("; ", x.DateOfVisits) .

Alternatively if you want to do something like:

Paul    01/01/2013
Paul    01/02/2013
Sally   01/01/2013

You could do

from x in listX
group x by new { x.PatronName, x.DateOfVisit } into g
select new String(g.Key.PatronName + "\t" + g.Key.DateOfVisit)

...don't have anything I can test with so this is all done "blind" as it were - hopefully will get you on right track.

Answer 2

you need to iterate through the collection (output variable) and then write them into a StringBuilder perhaps or write them directly to disk by using WriteLine on the StreamWriter object.

when you hover over the var variable, you will see it is a type of a collection being returned by the Select method (LINQ extension method). you need to iterate through it and write it line by line.