CODEWITHSUNDEEP
c#linqwindows-phone-8.1mvvm-light
user3411961
user3411961

Reputation: 125

Error An explicit conversion exists C#, MVVM Light - LINQ

I am learning MVVM Light and the app I am working on has a functionality to search for event names. Here are my codes for filtering a ListBox as the user types into TextBox. The error is: Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<NGO_Volunteer_Comm_Platform_v1._0.DataModel.Event>' to 'System.Collections.Generic.List<NGO_Volunteer_Comm_Platform_v1._0.DataModel.Event>'. An explicit conversion exists (are you missing a cast?)

ViewModel codes:

private static ObservableCollection<Event> _searchEventCollection = new ObservableCollection<Event>();

public static ObservableCollection<Event> SearchEventCollection
{
    get { return _searchEventCollection; }
    set { _searchEventCollection = value; }
}

//search from homepage event section
private RelayCommand _eventSearch;
/// <summary>
/// Gets the EventSearch.
/// </summary>
public RelayCommand EventSearch
{
    get
    {
        return _eventSearch
            ?? (_eventSearch = new RelayCommand(
            async () =>
            {
                SearchEventCollection.Clear();
                var eventList = await App.MobileService.GetTable<Event>().ToListAsync();

                foreach (Event ename in eventList)
                {
                    SearchEventCollection.Add(new Event
                    {
                        Id = ename.Id,
                        EventName = ename.EventName,
                        Date = ename.Date,
                        Location = ename.Location,
                        Desc = ename.Desc
                    });
                }
            }));
    }
}

private string filter;
public String Filter
{
    get
    {
        return this.filter;
    }
    set
    {
        this.filter = value;
        RaisePropertyChanged("SearchEventCollection");
    }
}
public List<Event> FilteredNames
{
    get
    {
        return (from name in SearchEventCollection where name.EventName.StartsWith(filter) select name);
    }
}        

public searchfromhomepageViewModel()
{
    filter = "";
}

How do I resolve this error?

Upvotes: 0

Views: 109

Answers (1)

Thomas Levesque
Thomas Levesque

Reputation: 292535

Use the ToList extension method to create a List<T> from an IEnumerable<T>:

public List<Event> FilteredNames
{
    get
    {
        return (from name in SearchEventCollection where name.EventName.StartsWith(filter) select name).ToList();
    }
}

Or change the type of the FilteredNames property to IEnumerable<Event>. Actually, that's probably a better idea. In general, you shouldn't expose concrete collection types publicly, because it doesn't let you return an instance of a different type if you need to change it later. Also, returning a List<T> seems to imply that you can modify the list. But since a new list is returned each time the property is called, modifying it will have no effect on the property, so it's misleading.

Upvotes: 2

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