C# Getting a column value with lambda and read the value on code behind

Question

my database table looks like this

i trying to retrieve the FileURL in the CRUD class file like this :

  public IList<string> GetSorted(int listAct)
        {
          IList<Model.story> lstImages = context.stories.ToList();
          return lstImages.Where(c => c.ActivityID == listAct)
                          .Select( a => a.FileURL)
                          .ToList();
        }

Am i doing it right? ( new to this )

Then in my aspx , i try to display the value like this ;

 protected void btnSort_Click1(object sender, EventArgs e)
    {
        if (dropListActivity.SelectedIndex > 0)// drop down list
        {
                  string imgList = daoStory.GetSorted(Convert.ToInt32(dropListActivity.SelectedItem.Value)).ToString();

            Response.Write(imgList);

        } 
    }

Basically the drop down list shows activityID 1 or 2 only , and when i select 1 and click the sort button , it will display the FileURL of '1' and if i select 2 , it will display FileURL of '2' so on from the above database table . However , it now shows System.Collections.Generic.List`1[System.String] instead of the FileURL , i want to show the FileURL as stated in the database table , pls help thanks.

Answer 1

First off, calling ToList will cause all the records to be retrieved from the database and processed. That's a pretty big waste of resources when all you need is a single record. I'd Suggest writing your DAO method like this:

public string GetFileUrl(int actId)
{
    return context.stories.First(c => c.ActivityID == actId).FileURL;
}

And then I think you want to use it like this:

protected void btnSort_Click1(object sender, EventArgs e)
{
    if (dropListActivity.SelectedIndex > 0)// drop down list
    {
        var actId = Convert.ToInt32(dropListActivity.SelectedItem.Value);
        var imageUrl = daoStory.GetFileUrl(actId);

        Response.Write(imageUrl);
    } 
}

This method assumes that you'll only have one FileUrl for each ActivityId. If that's not the case, you can easily modify the DAO code to return a IEnumerable<string> and use Where instead of First, but there's not enough information in the question for me to figure out what the button click handler is supposed to do with the result.

Answer 2

You're passing a list back from the sort method but converting it to a string in the code behind. You have to deal with the list somehow and get the value of whatever element you want.