How to read a Choice Field from Sharepoint 2010 Client Object Model - object

Question

I'm using Sharepoint 2010 Object Model. I'm trying to retrive the content of a Custom List. Everything works fine except if when I try to retrieve a Choice Field.
When I try to retrieve the choice field, I got an PropertyOrFieldNotInitializedException exception...
Here is the code I'm using:
ClientContext clientContext = new ClientContext("https://mysite");
clientContext.FormsAuthenticationLoginInfo = new FormsAuthenticationLoginInfo("aaa", bbb");
clientContext.AuthenticationMode = ClientAuthenticationMode.FormsAuthentication;
List list = clientContext.Web.Lists.GetByTitle("mylist");
CamlQuery camlQuery = new CamlQuery();
camlQuery.ViewXml = "<View/>";
ListItemCollection listItems = list.GetItems(camlQuery);
clientContext.Load(listItems);
clientContext.ExecuteQuery();
foreach (ListItem listItem in listItems)
{
listBoxControl1.Items.Add(listItem["Assigned_x0020_Company"]);
}

Answer 1

var list = clientContext.Web.Lists.GetByTitle(listName);
clientContext.ExecuteQuery();
clientContext.Load(list.Fields, fields => fields.Include(field => field.Title));
clientContext.ExecuteQuery();
foreach (var field in list.Fields)
{
if (field.Title == "YourChoiceFieldName")
{
clientContext.Load(field);
clientContext.ExecuteQuery();
return ((FieldChoice) field).Choices;
}
}

Answer 2

When you read a ChoiceField in code , It will return a string array of selected choices. For example if you entered in the choice box of the column when you create it : "Company 1" ,"Company 2","Company 3 " , if user select option 1 & 2 , then returned array in code will contain "Company 1" and "Company 2" .You must change the code to the below :
foreach (ListItem listItem in listItems)
{
string[] values = (string[])listItem["Assigned_x0020_Company"];
foreach(string s in values)
{
listBoxControl1.Items.Add(s);
}
}