C# List與Dictionary相互轉換與高效查找

TestModel類定義：

public class TestModel
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Code { get; set; }

}

Dictionary與List定義：

List<TestModel> list = new List<TestModel>();
Dictionary<int, TestModel> dict = new Dictionary<int, TestModel>();

Dictionary轉List：

dict = list.ToLookup(model => model.Id).ToDictionary(model => model.Key, model => model.First());

List轉Dictionary：

list = dict.Values.ToList();

高效查找：

foreach (TestModel item in list)
{
    if (dict.ContainsKey(item.Id))
    {
        TestModel model = dict[item.Id];
    }
}