使用 EF Core 過濾包含時無效的列名

Question

我在修改 DB 第一個項目（使用 fluent migrator）並搭建 EF 上下文以生成模型時遇到了這個錯誤。 我通過代碼優先的簡化復制了它。 這意味着我不能接受建議修改注釋或 fluent configuration 的答案，因為這將在下一次遷移和腳手架中被刪除和重新創建。

簡化的想法是設備具有：

• 許多屬性
• 代表設備隨時間變化的許多歷史記錄
  • 每個歷史條目都有一個可選的位置

IOW 您可以將設備四處移動到某個位置（或沒有位置），並隨着時間的推移進行跟蹤。

我想出的用於模擬這個的代碼優先模型如下：

public class ApiContext : DbContext
{
    public ApiContext(DbContextOptions<ApiContext> options) : base(options) { }

    public DbSet<Device> Devices { get; set; }
    public DbSet<History> Histories { get; set; }
    public DbSet<Location> Locations { get; set; }
}

public class Device
{
    public int DeviceId { get; set; }
    public string DeviceName { get; set; }

    public List<History> Histories { get; } = new List<History>();
    public List<Attribute> Attributes { get; } = new List<Attribute>();
}

public class History
{
    public int HistoryId { get; set; }
    public DateTime DateFrom { get; set; }
    public string State { get; set; }

    public int DeviceId { get; set; }
    public Device Device { get; set; }

    public int? LocationId { get; set; }
    public Location Location { get; set; }
}

public class Attribute
{
    public int AttributeId { get; set; }
    public string Name { get; set; }

    public int DeviceId { get; set; }
    public Device Device { get; set; }
}

public class Location
{
    public int LocationId { get; set; }
    public string LocationName { get; set; }

    public List<History> Histories { get; } = new List<History>();
}

運行以下查詢以選擇所有設備工作正常。 我正在使用過濾的包含來僅為此“視圖”選擇最近的歷史記錄：

var devices = _apiContext.Devices.AsNoTracking()
    .Include(d => d.Histories.OrderByDescending(h => h.DateFrom).Take(1))
    .ThenInclude(h => h.Location)
    .Include(d => d.Attributes)
    .Select(d => d.ToModel()).ToList();

效果很好，但是當我嘗試使用相同的 ID 僅選擇一台設備時，包括：

var device = _apiContext.Devices.AsNoTracking()
    .Include(d => d.Histories.OrderByDescending(h => h.DateFrom).Take(1))
    .ThenInclude(h => h.Location)
    .Include(d => d.Attributes)
    .First(d => d.DeviceId == deviceId)
    .ToModel();

我收到以下錯誤：

Unhandled exception. Microsoft.Data.SqlClient.SqlException (0x80131904): Invalid column name 'LocationId'.
Invalid column name 'HistoryId'.
Invalid column name 'DateFrom'.
Invalid column name 'LocationId'.
Invalid column name 'State'.
   at Microsoft.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at Microsoft.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at Microsoft.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at Microsoft.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at Microsoft.Data.SqlClient.SqlDataReader.TryConsumeMetaData()
   at Microsoft.Data.SqlClient.SqlDataReader.get_MetaData()
   at Microsoft.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString, Boolean isInternal, Boolean forDescribeParameterEncryption, Boolean shouldCacheForAlwaysEncrypted)
   at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean isAsync, Int32 timeout, Task& task, Boolean asyncWrite, Boolean inRetry, SqlDataReader ds, Boolean describeParameterEncryptionRequest)
   at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry, String method)
   at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
   at Microsoft.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior)
   at Microsoft.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
   at System.Data.Common.DbCommand.ExecuteReader()
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.InitializeReader(DbContext _, Boolean result)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at System.Linq.Queryable.First[TSource](IQueryable`1 source, Expression`1 predicate)
   at efcore_test.App.PrintSingleDevice(Int32 deviceId) in C:\Users\Iain\projects\efcore-5-bug\efcore-test\App.cs:line 44
   at efcore_test.Program.<>c__DisplayClass1_0.<Main>b__4(App app) in C:\Users\Iain\projects\efcore-5-bug\efcore-test\Program.cs:line 28
   at efcore_test.Program.RunInScope(IServiceProvider serviceProvider, Action`1 method) in C:\Users\Iain\projects\efcore-5-bug\efcore-test\Program.cs:line 35
   at efcore_test.Program.Main(String[] args) in C:\Users\Iain\projects\efcore-5-bug\efcore-test\Program.cs:line 28
ClientConnectionId:1418edb2-0889-4f4d-9554-85344c9a35a9
Error Number:207,State:1,Class:16

我無法弄清楚為什么這適用於多行但不適用於單行。

為了完整ToModel() ， ToModel()只是一個返回 POCO 的擴展方法。

我什至不知道從哪里開始尋找，歡迎提出想法！

Answer 1

看起來您遇到了 EF Core 查詢翻譯錯誤，因此我建議向 EF Core GitHub 問題跟蹤器尋求/報告它。

據我所知，這是由於Take運算符（基本上是First方法在第二種情況下使用的）而將根查詢作為子查詢“下推”引起的。 這以某種方式弄亂了生成的子查詢別名並導致無效的 SQL。

通過比較第一次查詢生成的SQL可以看出

SELECT [d].[DeviceId], [d].[DeviceName], [t0].[HistoryId], [t0].[DateFrom], [t0].[DeviceId], [t0].[LocationId], [t0].[State], [t0].[LocationId0], [t0].[LocationName], [a].[AttributeId], [a].[DeviceId], [a].[Name]
FROM [Devices] AS [d]
OUTER APPLY (
    SELECT [t].[HistoryId], [t].[DateFrom], [t].[DeviceId], [t].[LocationId], [t].[State], [l].[LocationId] AS [LocationId0], [l].[LocationName]
    FROM (
        SELECT TOP(1) [h].[HistoryId], [h].[DateFrom], [h].[DeviceId], [h].[LocationId], [h].[State]
        FROM [Histories] AS [h]
        WHERE [d].[DeviceId] = [h].[DeviceId]
        ORDER BY [h].[DateFrom] DESC
    ) AS [t]
    LEFT JOIN [Locations] AS [l] ON [t].[LocationId] = [l].[LocationId]
) AS [t0]
LEFT JOIN [Attribute] AS [a] ON [d].[DeviceId] = [a].[DeviceId]
ORDER BY [d].[DeviceId], [t0].[DateFrom] DESC, [t0].[HistoryId], [t0].[LocationId0], [a].[AttributeId]

對於第二個（或者只是在第一個Select之前插入.Where(d => d.DeviceId == deviceId).Take(1) ）：

SELECT [t].[DeviceId], [t].[DeviceName], [t1].[HistoryId], [t1].[DateFrom], [t1].[DeviceId], [t1].[LocationId], [t1].[State], [t1].[LocationId0], [t1].[LocationName], [a].[AttributeId], [a].[DeviceId], [a].[Name]
FROM (
    SELECT TOP(1) [d].[DeviceId], [d].[DeviceName]
    FROM [Devices] AS [d]
    WHERE [d].[DeviceId] = @__deviceId_0
) AS [t]
OUTER APPLY (
    SELECT [t].[HistoryId], [t].[DateFrom], [t].[DeviceId], [t].[LocationId], [t].[State], [l].[LocationId] AS [LocationId0], [l].[LocationName]
    FROM (
        SELECT TOP(1) [h].[HistoryId], [h].[DateFrom], [h].[DeviceId], [h].[LocationId], [h].[State]
        FROM [Histories] AS [h]
        WHERE [t].[DeviceId] = [h].[DeviceId]
        ORDER BY [h].[DateFrom] DESC
    ) AS [t0]
    LEFT JOIN [Locations] AS [l] ON [t].[LocationId] = [l].[LocationId]
) AS [t1]
LEFT JOIN [Attribute] AS [a] ON [t].[DeviceId] = [a].[DeviceId]
ORDER BY [t].[DeviceId], [t1].[DateFrom] DESC, [t1].[HistoryId], [t1].[LocationId0], [a].[AttributeId]

請注意[t]在OUTER APPLY中的第一個SELECT [t].[HistoryId]...的用法，它在第一個查詢中是FROM子句中內部Histories子查詢的別名，而在第二個查詢中它是外部Devices子查詢，其中當然沒有錯誤消息中提到的列。 顯然在第二種情況下應該使用[t0] 。

由於它是一個錯誤，您必須等待它被修復。 在那之前，我建議的解決方法是在 EF Core 查詢上下文之外顯式執行行限制運算符（ First ），例如

var device = _apiContext.Devices.AsNoTracking()
    .Include(d => d.Histories.OrderByDescending(h => h.DateFrom).Take(1))
    .ThenInclude(h => h.Location)
    .Include(d => d.Attributes)
    .Where(d => d.DeviceId == deviceId) // instead of .First(d => d.DeviceId == deviceId)
    .AsEnumerable() // switch to client evaluation (LINQ to Objects context)
    .First() // and execute `First` here
    .ToModel();