无法从 'System.Collections.Generic.IEnumerable<string>' 转换为 'T'

Question

我希望这是我完全想念的非常简单的东西，但我似乎无法弄清楚这里需要更改什么。

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

编译错误来自这里的这个块，特别是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;

DataItem 的声明来自此 class 此处：

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

什么是keyFilter？我猜它是 returns IEnumerable，这意味着它的 Dictionary 上没有 Contains() 重载。您可能需要以下内容：

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

无法从 'System.Collections.Generic.IEnumerable<string>' 转换为 'T'

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

c#

generics

ienumerable