C# – ASP.NET: How to get values from a selected row from GridView control

asp.netaspxgridviewcgridview

I have added a GridView control on my ASP.net webpage and data bound it to a List<> the list contains a collection of a simple custom objects which is defined as:

public class PersonRecord
{
    public int PersonId { get; set; }
    public string Name { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public string Notes { get; set; }
}

I have set AutoGenerateSelectButton to true and and attached an event handler to the SelectedIndexChanged event. I can see my event handler fires and I can get the selected row index by using MyGridView.SelectedIndex.

My question is: how do I use the selected row index to get the PersonId for the selected record?

I thought MyGridView.Rows[MyGridView.SelectedIndex].Cells[0] would do it but it doesn't because MyGridView.Rows.Count is 0.

TIA

Best Answer

Just because I have not played with web applications in awhile, I decided to see if this was something I could dupe. Alas, to no avail. This works fine for me:

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if(!Page.IsPostBack)
        {
            var persons = CreatePersons();
            GridView1.DataSource = persons;
            GridView1.DataBind();
        }
    }

    private List<PersonRecord> CreatePersons()
    {
        var person = new PersonRecord
                         {
                             PersonId = 1,
                             Name = "greg",
                             Title = "Supreme Coder",
                             Description = "Nada",
                             Notes = "foo bar"
                         };

        var person2 = new PersonRecord
        {
            PersonId = 2,
            Name = "Sam",
            Title = "Junior Coder",
            Description = "Nada",
            Notes = "foo bar"
        };

        var list = new List<PersonRecord> {person, person2};

        return list;
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        var row = GridView1.Rows[0];
        var cell = row.Cells[1];
        var value = cell.Text;


    }

    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        int index = GridView1.SelectedIndex;
        var row = GridView1.Rows[index];
        var nameCell = row.Cells[2];
        var name = nameCell.Text;

        Label1.Text = name;
    }
}

Yours most likely fails as you are selecting the select column (cell[0]), but I would think you should get something out of this cell (have to play with it). It could also be a bad pattern for binding.

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common

C# – How to get a consistent byte representation of strings in C# without manually specifying an encoding

Contrary to the answers here, you DON'T need to worry about encoding if the bytes don't need to be interpreted!

Like you mentioned, your goal is, simply, to "get what bytes the string has been stored in".
(And, of course, to be able to re-construct the string from the bytes.)

For those goals, I honestly do not understand why people keep telling you that you need the encodings. You certainly do NOT need to worry about encodings for this.

Just do this instead:

static byte[] GetBytes(string str)
{
    byte[] bytes = new byte[str.Length * sizeof(char)];
    System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
    return bytes;
}

// Do NOT use on arbitrary bytes; only use on GetBytes's output on the SAME system
static string GetString(byte[] bytes)
{
    char[] chars = new char[bytes.Length / sizeof(char)];
    System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
    return new string(chars);
}

As long as your program (or other programs) don't try to interpret the bytes somehow, which you obviously didn't mention you intend to do, then there is nothing wrong with this approach! Worrying about encodings just makes your life more complicated for no real reason.

Additional benefit to this approach: It doesn't matter if the string contains invalid characters, because you can still get the data and reconstruct the original string anyway!

It will be encoded and decoded just the same, because you are just looking at the bytes.

If you used a specific encoding, though, it would've given you trouble with encoding/decoding invalid characters.

Best Answer

Related Solutions

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

For MVC v5 use EnumHelper

For MVC 5 and lower

C# – How to get a consistent byte representation of strings in C# without manually specifying an encoding

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