Populate Combobox from a list

Question

Newb here, I'm currently working on a form which has a combo box, which will show several Charlie Brown TV specials which you can click on to select and see a description of, rating, runtime, etc. I'm close but I'm not there in terms of populating the combo box and i'm hoping for some help and guidance. I have looked at several things others have done but i'm not knowledgeable enough to deduce the answers from what i've been able to see so far.

Right now i'm trying too: 1. get the listings from your load method 2. loop through them 3. Access my combo box to populate the box with the times from the listing.

Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

using System.Globalization;//Used for Sting.ToUpperCase...
using System.Threading;

using System.Threading.Tasks;// Needed for Streaming...
using System.IO;// Needed for Streaming...


namespace a100___GUI___VideoStoreSelections
{
public partial class FormMovieLookUp : Form
{
    private const String FILE_NAME = "txt_movieDescriptions.txt";//connect to text file in debug

    private List<Listing> films { get; set; }

    public FormMovieLookUp()
    {
        InitializeComponent();
    }

    private void cmbMovieListingBox_SelectedIndexChanged(object sender, EventArgs e)
    {
        txtTitleBox.Text = cmbMovieListingBox.SelectedItem.ToString();
    }

    //ToolBox -- my program specific tools
    public List<Listing> LoadListings()//load movie descriptions as list
    {
        StreamReader fileIn = new StreamReader(FILE_NAME);
        List<Listing> entries = new List<Listing>();

        //loop through every line of the file
        while (!fileIn.EndOfStream)
        {
            String line = fileIn.ReadLine();
            String[] pieces = line.Split(':');

            if (pieces.Length < 4) continue;//error handling - set to length of text items

            Listing myListing = new Listing(pieces[0], pieces[1], pieces[2], pieces[3]);
            entries.Add(myListing);
        }
        fileIn.Close();
        return entries;
    }

    private void FormMovieLookUp_Load_1(object sender, EventArgs e)
    {
        films = LoadListings();
        foreach (Listing film in films)
        {
            Console.WriteLine(film);
            cmbMovieListingBox.Items.Add(film.GetFilmTitle());
        }
    }
}
}

Listing.CS

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace a100___GUI___VideoStoreSelections
{

public class Listing
{
    private String filmTitle;
    private String description;
    private String filmRunTime;
    private String filmRating;

    public Listing(String filmTitle, String description, String filmRunTime, String filmRating)
    {
        this.filmTitle = filmTitle;
        this.description = description;
        this.filmRunTime = filmRunTime;
        this.filmRating = filmRating;
    }

    public String GetFilmTitle() { return filmTitle; }
    public String GetDescription() { return description; }
    public String GetFilmRunTime() { return filmRunTime; }
    public String GetFilmRating() { return filmRating; }



}

}

So this is what i'm trying to do to populate my combo box. Any help is thankfully received.

Answer 1

I would hold List<Listing> at the class level so you can access it when a user clicks on it. I would also throw this on it's own thread and not directly in the Load event. If it's a long process you will hang the ui.

private List<Listing> films { get; set; }

Load

films = LoadListings();
foreach (Listing film in films)
{
    cmbMovieListingBox.Items.Add(film.GetFilmTitle());
}

When the user selects the item

Listing film = films.Where(f => f.GetFilmTitle().Equals(cmbMovieListingBox.SelectedValue)).FistOrDefault();

if (film != null)
{
    //do work
}

Answer 2

if you are asking what i think you are asking, you need something like this in your form load:

foreach(Listing listing in LoadListings()){
    cmbMovieListingBox.Items.Add(listing.GetFilmTitle());
}

Answer 3

There's one issue with visual controls updating (such as ComboBox etc): you'd rather prevent them from re-painting at each data change (at each item addition in your case):

cmbMovieListingBox.BeginUpdate(); // <- Stop painting

try {
  // Adding new items into the cmbMovieListingBox 
  foreach(var item in LoadListings())
    cmbMovieListingBox.Items.Add(item.GetFilmTitle());
finally {
  cmbMovieListingBox.EndUpdate(); // <- Finally, repaint if required
}

Answer 4

A line of the code of Tsukasa doesn't work because it is written FistOrDefault() instead of FirstOrDefault()

Listing film = films.Where(f => f.GetFilmTitle().Equals(cmbMovieListingBox.SelectedValue)).**First**OrDefault();

Sorry I don't have enough point to just add a comment...

Answer 5

Remove the {get; set;} from the list declaration. It's not needed there.

Define your class like this:

public class Listing
{
    private String filmTitle {get; set;}
    private String description {get; set;};
    …
}

On the form load event set the ComboBox DisplayMember and ValueMember to "filmTitle"

cmbMovieListingBox.DisplayMember = "filmTitle";
cmbMovieListingBox.ValueMember = "filmTitle"

Finally, you must set the DataSource of the ComboBox to the list

cmbMovieListingBox.DataSource = films;

And there you have it. The rest of your code should function now.

Answer 6

Maybe it will help somebody. But in my situation I had to use cmbMovieListingBox.Text instead of cmbMovieListingBox.SelectedValue (like @Tsukasa example):

Listing film = films.Where(f => f.GetFilmTitle().Equals(cmbMovieListingBox.Text)).FirstOrDefault();

if (film != null)
{
    //do work
}

And also FirstOrDefault() instead of FistOrDefault().

Hope it helps to someone

Answer 7

that what i did to my Code

int Count;
foreach(String i in Languages)
{
    LangComboBox.Items.Add(Languages[Count]);
    Count++;
}