Generating a list from csv to listbox

Question

I am trying to generate a list from a database that I have and add it to a listbox in WPF C# with LINQ.

This is the XAML I have for now:

<ListView x:Name="ListBox" Margin="16,232,22,10.4" SelectionMode="Multiple">
        <ListView.View>
            <GridView>
                <GridViewColumn Header="Nettstasjon" Width="100" DisplayMemberBinding="{Binding Path=Name}"/>
                <GridViewColumn Header="Område" Width="100" DisplayMemberBinding="{Binding Path=Area}"/>
                <GridViewColumn Header="Radial" Width="100" DisplayMemberBinding="{Binding Path=Radial}"/>
            </GridView>
        </ListView.View>
    </ListView>

And to read the database I have this codebehind. I made a class "TransformerStation" to hold the data per line.

public class TransformerStation : INotifyPropertyChanged
    {
        public string Name { get; set; }
        public string Radial { get; set; }
        public string Area {get; set; }

        public event PropertyChangedEventHandler PropertyChanged;
    }

Then I made a class to read the database

public IEnumerable<TransformerStation> ReadCSV(string fileName, string radial)
    {

        string[] lines = File.ReadAllLines(System.IO.Path.ChangeExtension(fileName, ".csv"), Encoding.UTF8);


        return lines.Select(line =>
        {
            string[] data = line.Split(';');

            foreach (var value in data)
            {
                if (data = radial)
                {
                    return new TransformerStation(data[0], data[1], data[2]);
                }
            }     
        });
    }

My database looks like this:

N765;TANGEN;TANGEN L98
R2351;SPIKKESTAD;SPIKKESTAD K88
S622;KRÅKSTAD;KRÅKSTAD L812
S1318;KRÅKSTAD;KRÅKSTAD L812

What I need is as follows:

I have a WPF with butttons with content that is equal to the third column in my database(F.eks KRÅKSTAD L812). I want, when I push a button, to collect all the items in column one from my database, that matches the button content in column three, and show them in a listbox that I have created above.

So, if I push the button with content "Kråkstad L812" then my list will show

S622
S1318

I am sorry, I am really new at C# and WPF. So I dont have much code to show. But I really appreciate all the help I can get and it really makes a difference if you explain what is happening in the code :) So just to clarify, I basically need the SELECT radial FROM database and generate a list from that.

EDIT, I am also open to other ways of importing the data from the csv database. I have just picked one that worked for me :)

Answer 1

Hard to give an complete answer since not all your code is given, and you might want to refactor some of it later as you develop you complete project. So I might offer some advice to get you going farther along. You will need to search/research some of these things, but since you are new to c#/wpf, you were planning on this anyway, right? :)

...fix the == like @wentimo pointed out...

For returning IEnumerable, you might look at yield.

It looks like you might be reading your database many times. If it is changing all the time, that might be fine. If it is more static, consider reading it once and storing it in a Dictionary where Name is the key and TransformerStation is a value. Then for each lookup you can can use .Where clause to filter.

See this post and read the answers to learn more. Maybe this is relevant:

var keysForValues = dictionary.Where(pair => values.Contains(pair.Value))
                          .Select(pair => pair.Key);

There is no one best way...research Dictionary, List, List<Tuple, etc.

Some Sample Code (create in Console project)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Diagnostics;

namespace ConsoleApplication1
{
    [DebuggerDisplay("{Name} {Radial} {Area}")]
    public class TransformerStation
    {
        public string Name { get; set; }
        public string Radial { get; set; }
        public string Area { get; set; }

        public TransformerStation(string name, string radial, string area)
        {
            Name = name;
            Radial = radial;
            Area = area;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            CSVToDictionary();
        }

        private static void CSVToDictionary()
        {
            var dictionary = new Dictionary<string, TransformerStation>();

            // your csv
            string[] lines = new string[] {
            "N765; TANGEN; TANGEN L98",
            "R2351; SPIKKESTAD; SPIKKESTAD K88",
            "S622; KRÅKSTAD; KRÅKSTAD L812",
            "S1318; KRÅKSTAD; KRÅKSTAD L812"};

            foreach (var line in lines)
            {
                var data = line.Split(';');
                dictionary.Add(data[0], new TransformerStation(data[0].Trim(), data[1].Trim(), data[2].Trim()));
            }

            var find = "KRÅKSTAD L812";
            var search = dictionary.Values.Where(v => v.Area == find);

            foreach (var found in search)
            {
                Console.WriteLine($"Matches: {found.Name} {found.Radial} {found.Area}");
            }
        }
    }
}

What you should learn from this

• DebuggerDisplay (use debugger to see a nicer representation of your data)
• Simulating reading your csv and storing in dictionary
• Trimming spaces from input data (you never trust data read in, always verify/clean)
• Filtering data using linq
• Outputting results using String interpolation

Good luck with your project.

Answer 2

Quite a few problems here. First of all you're not actually implementing INotifyPropertyChange support correctly. Probably the easiest thing to do here is to add MVVM Lite to your project (it'll only take a minute if you use NuGet) and base your view models off ViewModelBase:

public class TransformerStation : ViewModelBase
{
    private string _Name;
    public string Name
    {
        get { return this._Name; }
        set { this._Name = value; RaisePropertyChanged(); }
    }

    private string _Radial;
    public string Radial
    {
        get { return this._Radial; }
        set { this._Radial = value; RaisePropertyChanged(); }
    }

    private string _Area;
    public string Area
    {
        get { return this._Area; }
        set { this._Area = value; RaisePropertyChanged(); }
    }

    public TransformerStation(string name, string radial, string area)
    {
        this.Name = name;
        this.Radial = radial;
        this.Area = area;
    }

}

The second thing I notice is that you seem to be filtering your data when you load it, which suggest you're re-loading every time the user pressed a button. Unless you have a really large amount of data you may as well keep the whole thing stored in memory and filter it after it's been loaded. A dictionary will not only make the filtering process faster it will also provide you with a list of all radials in the data set, should you require that at runtime for creating your buttons dynamnically:

    public Dictionary<string, List<TransformerStation>> ReadCSV(string fileName)
    {

        string[] lines = File.ReadAllLines(System.IO.Path.ChangeExtension(fileName, ".csv"), Encoding.UTF8);
        return lines.Select(line =>
        {
            string[] data = line.Split(';');
            return new TransformerStation(data[0], data[1], data[2]);
        })
        .GroupBy(ts => ts.Radial)
        .ToDictionary(g => g.Key, g => g.ToList());
    }

Back in your MainViewModel you'll need to load the data and store it somewhere (i.e. AllStations), you'll need a property like "SelectedRadial" which you set in response to the user pressing buttons, and another ("CurrentStations") which is the filtered version of AllStations:

    private Dictionary<string, List<TransformerStation>> _AllStations;
    public Dictionary<string, List<TransformerStation>> AllStations
    {
        get { return this._AllStations; }
        private set { this._AllStations = value; RaisePropertyChanged(); }
    }


    private string _SelectedRadial;
    public string SelectedRadial
    {
        get { return this._SelectedRadial; }
        set
        {
            this._SelectedRadial = value;
            RaisePropertyChanged();
            this.CurrentStations = this.AllStations[value];
        }
    }

    private List<TransformerStation> _CurrentStations;
    public List<TransformerStation> CurrentStations
    {
        get { return this._CurrentStations; }
        private set { this._CurrentStations = value; RaisePropertyChanged(() => this.CurrentStations); }
    }

    public ICommand RadialCommand {get { return new RelayCommand<string>(OnRadialCommand); }}
    private void OnRadialCommand(string radial)
    {
        this.SelectedRadial = radial;
    }


    public MainViewModel()
    {
        this.AllStations = ReadCSV(@"data.csv");
    }

Then it's just a matter of binding some minimal XAML to generate the buttons (again, that's optional) and display your data:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="Auto"/>
        <ColumnDefinition />
    </Grid.ColumnDefinitions>

    <ListBox ItemsSource="{Binding AllStations.Keys}">
        <ListBox.ItemTemplate>
            <ItemContainerTemplate>
                <Button Command="{Binding Path=DataContext.RadialCommand, RelativeSource={RelativeSource AncestorType={x:Type ListBox}}}" CommandParameter="{Binding}">
                    <TextBlock Text="{Binding}" />
                </Button>
            </ItemContainerTemplate>
        </ListBox.ItemTemplate>
    </ListBox>

    <ListView Grid.Column="1" ItemsSource="{Binding CurrentStations}" >
        <ListView.View>
            <GridView>
                <GridViewColumn Header="Nettstasjon" Width="100" DisplayMemberBinding="{Binding Path=Name}"/>
                <GridViewColumn Header="Område" Width="100" DisplayMemberBinding="{Binding Path=Area}"/>
                <GridViewColumn Header="Radial" Width="100" DisplayMemberBinding="{Binding Path=Radial}"/>
            </GridView>
        </ListView.View>
    </ListView>

</Grid>

Result:

Answer 3

Seems like your if statement

if (data = radial)

Should be:

if (data == radial)

Because = is an assignment and == is an equals operation.

Besides that, I guess you want something like: If user input exists somewhere in the database.. return the matches.

If so, use IndexOf instead of == like so:

if (data[0].IndexOf(radial, StringComparison.OrdinalIgnoreCase) >= 0)
{
    // return new ..
}

Though the above only checks for data[0]. You could use the foreach loop like you have now to compare all data in row. Or use:

if (data.Any(dataPart => dataPart.IndexOf(radial, StringComparison.OrdinalIgnoreCase) >= 0)
{
    // return new ..
}