MVC实体框架将一列作为数组

Question

my application is asp.net MVC3 using Entity Framework. I am trying to get a list of one column from a table as an array using the following:

   public ActionResult Index()
        {
            //var list = db.CasesProgresses.ToList();
            var SeriesList = GetSeriesList(Learner_ID);
            return View();
        }



        public List<string> GetSeriesList(string item)
        {
            // get DataTable dt from somewhere.
            List<string> sList = new List<string>();
            foreach (CasesProgress row in db.CasesProgresses)
            {
                sList.Add(row[0].ToString());
            }
            return sList;  
        }

I get two errors:

Cannot apply indexing with [] to an expression of type 'caseprog.Models.CasesProgress' and
The name 'Learner_ID' does not exist in the current context

Would appreciate your suggestions.

Answer 1

You probably need to read the Property name of your CasesProgress object

Change this

sList.Add(row[0].ToString());

to

sList.Add(row.YourPropertyNameHereWhichIsOfStringType);

If the Property is not of string type, ( ex : Integer / decimal ) you may apply ToString() method on that and then add to the string collection.

sList.Add(row.Learner_ID.ToString());

Assuming Learner_ID is a property of CasesProgress class with numeric type.

Answer 2

 foreach (CasesProgress row in db.CasesProgresses)
 {
   sList.Add(row.SomePropertyYouNeed.ToString());
 }

if you are using a foreach, there is no [0] . If you were using a normal for (int i =0; i < list.Count; i ++;) then you would be able to do that. But then ofcourse you would have to change the 0 to i , and you would still need to access a property. Well you wouldn't have to do that if your List had a different type, but in your current example you will need to add a String.

Answer 3

The name 'Learner_ID' does not exist in the current context 
GetSeriesList(Learner_ID);

Learner_ID - is not defined in your action and you can remove it, because parameter in GetSeriesList(string item) is not used (also remove parameter).

Cannot apply indexing with [] to an expression of type 'caseprog.Models.CasesProgress'

In foreach row is separate item from collection, that's why you shoud access it by property with dot notation row.Property .

Answer 4

Why not just keep it simple and use the 'usual' syntax

var list = db.CasesProgresses.Select(o=>o.YourPropertyName).ToList();

If its an int and you need it as a string list simply replace YourPropertyName with YourPropertyName.ToString() above