c# - 如何合并返回匿名类型的 lambda 的 LINQ 查询？

Question

我正在尝试合并其中的 2 个列表:

var quartEst = Quarterly_estimates
.OrderByDescending (q => q.Yyyy)
.ThenByDescending (q => q.Quarter)
.Where (q => 
    q.Ticker.Equals("IBM")
    &&
    q.Eps != null
    )
.Select (q => new {
    ticker = q.Ticker,
    Quarter = q.Quarter,
    Year = q.Yyyy,
    Eps = q.Eps})
.AsEnumerable()
.Where (q => Convert.ToInt32(string.Format("{0}{1}", q.Year, q.Quarter)) > Convert.ToInt32(finInfo) );

var quartAct = Quarterlies
.OrderByDescending (q => q.Yyyy)
.ThenByDescending (q => q.Quarter)
.Where (q => 
    q.Ticker.Equals("IBM")
    &&
    Convert.ToInt16(q.Yyyy) >= DateTime.Now.Year - 3
    )
.Select (q => new {
    Tick = q.Ticker,
    Quarter = q.Quarter,
    Year = q.Yyyy,
    Eps = q.Eps_adj})
.AsEnumerable()
.Where (q => Convert.ToInt32(string.Format("{0}{1}", q.Year, q.Quarter)) <= Convert.ToInt32(finInfo));

我得到一个简单的 Union 命令的错误:

var quartComb = quartEst.Union(quartAct);

这是错误:

Instance argument: cannot convert from 'System.Collections.Generic.List<AnonymousType#1>' to 'System.Linq.IQueryable<AnonymousType#2>'

我需要做什么来实现这个合并？

Answer 1

要使用Union 方法，集合必须具有相同的类型。为了使两个匿名类型被认为是相同的，它们必须具有完全相同的成员和完全相同的类型。

试试这个:

var quartEst = Quarterly_estimates
    ...
    .Select (q => new {
        Tick = q.Ticker,       // renamed ticker to Tick
        Quarter = q.Quarter,
        Year = q.Yyyy,
        Eps = q.Eps})
    ...

var quartAct = Quarterlies
    .Select (q => new {
        Tick = q.Ticker,
        Quarter = q.Quarter,
        Year = q.Yyyy,
        Eps = q.Eps_adj})
    ...

var quartComb = quartEst.Union(quartAct);