c# - 根据字典查找查询填充字符串

Question

所以我有以下查询

        IQueryable<Feedback> query = db.Feedbacks;
        var result = query
            .Select(s => new FeedbackViewModel
            {
                businessId = s.Account.Businesses.FirstOrDefault().businessId,
                hireSuccess = s.hireSuccess.Value,
                useAgain = s.useAgain.Value,
                suggestions = s.suggestions,
                employees = numberGroups[s.numEmployees.Value]
            });
        return result;

我得到了错误

Additional information: LINQ to Entities does not recognize the method 'System.String get_Item(Int32)' method, and this method cannot be translated into a store expression.

由于试图从字典查找中设置员工字符串，字典看起来像这样。

    public static Dictionary<int, string> numberGroups = new Dictionary<int, string>()
    {
        { 0, "None" },
        { 9, "1 to 9" },
        { 19, "10 to 19" },
        { 49, "20 to 49" },
        { 100, "50 to 100" }
    };

FeedbackViewModel 看起来像这样

public class FeedbackViewModel
{
    public int businessId { get; set; }
    public bool hireSuccess { get; set; }
    public bool useAgain { get; set; }
    public string suggestions { get; set; }
    public string employees { get; set; }
}

我做错了什么？

Answer 1

我认为您正在尝试从数据库中查询某些内容。 Linq To SQL 不支持像 numberGroups[s.numEmployees.Value] 这样的方法。

你可以考虑做这样的事情。

          var query = db.Feedbacks.Select(f = > new
                {
                    businessId = s.Account.Businesses.FirstOrDefault().businessId,
                    hireSuccess = s.hireSuccess.Value,
                    useAgain = s.useAgain.Value,
                    suggestions = s.suggestions.Value,
                    numEmployees = s.numEmployees.Value
                }).ToList();


          var result = query
              .Select(s => new FeedbackViewModel
                {
                    businessId = s.businessId,
                    hireSuccess = s.hireSuccess,
                    useAgain = s.useAgain,
                    suggestions = s.suggestions,
                    employees = numberGroups[s.numEmployees]
                }).ToList();