Add data into lists at runtime, from a database

Question

Presentation:

I am trying to write classes to store data from a database.

The data consists in objects, let's call them "Areas". Each area has a name and possibly 'child' areas:

public class Area {
    public string Name;
    public List<Area> SubAreas = new List<Area>();
}

The program reads data from the database (out of the scope of this review), and creates a new Data object to store this data.

The data is returned as a 2D array of stings: [ [areaName, parentAreaName], ...]

With the following assumptions:

The parent of a root-level area is String.Empty
The parent item is before (in the array) any child item (-> no recurrence needed).

Code:

public static void Main()
    {
        //This comes from the DB
        string[,] areas = new string[4,2] {{"1",""}, {"11","1"},{"12","1"},{"2",""}};   

        new Data(areas);
    }

public class Data {
    public List<Area> Areas = new List<Area> ();

    public Data(string[,] areasArray)
    {
        for (int i = 0; i < areasArray.GetLength(0); i++) {
            Area loopSubArea;
            if (areasArray[i,1] != "") {
                loopSubArea = Areas.Where(a => a.Name == areasArray[i,1]).First();
                loopSubArea.SubAreas.Add(new Area() {Name = areasArray[i,0]});
            } else {
                Areas.Add(new Area() {Name = areasArray[i,0]});
            }
        }
    }
}

The full working code is also available in a Fiddle

My concerns:

I initialize the lists during the object creation, meaning that I have possibly a lot of empty Lists around. Is that an issue?
I feel like the loop part could be improved, but I have not been able to think of anything better
I am a beginner in C#, any general advice is of course welcome.

ogomrub · Accepted Answer · 2017-10-03 11:46:52Z

regarding your concerns.

1) I do not believe this initialization is a problem but if later on it will be a problem, you can always change it to lazy initialization.

2,3) I just paste a similar code that I find more readable and improves your loop when you want to find the parent area.

    public class Data
    {
        public List<Area> Areas = new List<Area>();

        public Data(string[,] areasArray)
        {
            for (int i = 0; i < areasArray.GetLength(0); i++)
            {
                var areaName = areasArray[i, 0];
                var parentAreaName = areasArray[i, 1];

                if (string.IsNullOrEmpty(parentAreaName))
                {
                    Areas.Add(new Area() { Name = areaName });
                }
                else
                {
                    var parentArea = Areas.First(a => a.Name == parentAreaName);
                    parentArea.SubAreas.Add(new Area() { Name = areaName });
                }
            }
        }
    }

You can probably still improve the loop but I guess you will lost readability, so I would leave it like this unless you face a real performance issue.

Regards

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