Error: Could not understand expression: .OfType().GroupBy(a => a.Id) RavenDb

Question

我目前正在尝试从数据库中获取发票的正确增值税百分比。我的代码如下所示：

var lines = store.Query<DebetInvoiceItemAll.Mapping, DebetInvoiceItemAll>()
               .Where(a => a.InvoiceId.Equals(invoice.Id, StringComparison.OrdinalIgnoreCase))
               .As<DebetInvoiceDistributedPurchaseItem>()
               .All().ToList();
value = info.Amount;
decimal totalInvoicePrice = invoice.TotalDecimal ?? 0m;
decimal percentagePaid = value / totalInvoicePrice;
var rates = store.Query<VATPercentageAll.Mapping, VATPercentageAll>()
                .As<VATPercentage>()
                .GroupBy(a => a.Id)
                .ToDictionary(a => a.Key, a => a
                .ToDictionary(b => b.CountryId, b => b.Percentage, StringComparer.OrdinalIgnoreCase));

当我尝试运行代码时，它在最后一行崩溃了。错误说：

Could not understand expression: .OfType().GroupBy(a => a.Id).

但是问题不在 myGroupBy 中，而是在 ToDictionary 中。有谁知道为什么会抛出这个异常？提前致谢。

Answer 1

您正在尝试对 RavenDB 查询运行 GroupBy，但这不受支持。如果你想做group bys，你需要使用一个map/reduce索引。

Error: Could not understand expression: .OfType().GroupBy(a => a.Id) RavenDb

Error: Could not understand expression: .OfType().GroupBy(a => a.Id) RavenDb

c#

ravendb