无法从“System.Collections.Generic.IEnumerable”转换<string> &#39; 到 &#39;T&#39;

Question

I hope this is something really simple that I am just completely missing, but I can't seem to figure out what needs to be changed here.

cannot convert from System.Collections.Generic.IEnumerable<string> to T

The compile error is coming from this block here, specifically item.DataItem:

    public List<ImportItem<T>> ProcessReportResult(CSVTable resultData, ICollection<ImportItem<T>> data, Func<T, IEnumerable<string>> keyFilter)
    {
        WriteLog("{1}{0} records found.{1}", resultData.Rows.Length, Environment.NewLine);

        //key = Order Number; value = Order ID
        var idDictionary = resultData.Rows.Select((row => row.Split(','))).ToLookup(id => id[0], id => id[1]);

        idDictionary.ForEach(id => WriteLog("Input Id = {0} - Matching record Id = {1}", id.Key));

       var processList = data.Where(item => idDictionary.Contains(keyFilter(item.DataItem))).ToList();

        processList.ForEach(item => item.Id = idDictionary[keyFilter(item.DataItem)]);

        return processList;

The declaration of DataItem is coming from within this class here:

public class ImportItem<T> : INotifyPropertyChanged
{
    public IEnumerable<string> DataItem
    {
        get; set; 

    }

    private bool visible;
    public bool Visible
    {
        get { return visible; }
        set
        {
            visible = value;
            RaisePropertyChanged("Visible");
        }
    }

    public string ErrorMessage { get; set; }

    public IEnumerable<string> Id
    {
        get; set;
    }

    public Status Status { get; set; }

    public ImportItem(T item)
    {
        DataItem = (IEnumerable<string>) item;
        visible = true;
    }

    private void RaisePropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

Answer 1

What is keyFilter? I'm guessing it returns IEnumerable, which means that there's no Contains() overload on a Dictionary for it. You probably want the following:

var processList = 
data.Where(item => keyFilter(item.DataItem).Any(key => idDictionary.ContainsKey(key))).ToList()