EF Core LINQ 查询因限制而失败？

Question

我正在尝试使用 EF Core 3.0 进行非常简单的分组和求和

但是我收到一个奇怪的错误：

System.InvalidOperationException: 'Processing of the LINQ expression 'AsQueryable((Unhandled parameter: y).TransactionLines)' by 'NavigationExpandingExpressionVisitor' failed. This may indicate either a bug or a limitation in EF Core.

 var creditBalances = await context.Transaction
                .Include(x => x.TransactionLines)
                .Include(x=>x.CreditAccount)
                .Where(x => x.CreditAccount.UserAccount.Id == userAccount.Id)
                .GroupBy(x => new
                {
                    x.CreditAccount.ExternalId
                })
                .Select(x => new
                {
                    x.Key.ExternalId,
                    amount = x.Sum(y => y.TransactionLines.Sum(z => z.Amount))
                })
                .ToListAsync();

我正在努力寻找可能出现问题的地方，所以甚至不确定从哪里开始。我正在尝试获取所有交易金额的总和（这是每笔交易的所有 TransactionLines 的总和 - 即交易金额由与其关联的行组成）。

然后我总结所有交易，然后按 CreditAccount ID 分组。

这条线，Unhandled parameter: y令人担忧。可能我的分组求和不行了

Answer 1

所以从 TransactionLines 级别开始，这很简单：

var q = from c in context.TransactionLines
        where c.Transaction.CreditAccount.UserAccount.Id == userAccount.Id
        group c by c.Transaction.CreditAccount.ExternalId into g
        select new
        {
            ExternalId = g.Key,
            Amount = g.Sum(x => x.Amount)
        };

var creditBalances = await q.ToListAsync();

（您不需要任何 Include()，因为您不会返回具有相关数据的实体。您正在投影自定义数据形状。）

转换为：

SELECT [c].[ExternalId], SUM([t].[Amount]) AS [Amount]
FROM [TransactionLines] AS [t]
LEFT JOIN [Transaction] AS [t0] ON [t].[TransactionId] = [t0].[Id]
LEFT JOIN [CreditAccounts] AS [c] ON [t0].[CreditAccountId] = [c].[Id]
LEFT JOIN [UserAccount] AS [u] ON [c].[UserAccountId] = [u].[Id]
WHERE [u].[Id] = @__userAccount_Id_0
GROUP BY [c].[ExternalId]

EF Core LINQ 查询因限制而失败？

EF Core LINQ query failing due to limitation?

c#

entity-framework

ef-core-3.0