linq invalidoperationException调用TOLIST（）

发布于 2025-01-30 20:07:42 字数 784 浏览 3 评论 0原文

我想使用下面的代码在数据库中的表中更新记录：

context.Events
        .Where(eventDb => !events.Any(@event => eventDb.Guid == @event.Guid))
        .ToList()
        .ForEach(eventDb => eventDb.IsCurrent = false);

但是每次调用Tolist（）我会收到以下错误，这对我来说尚不清楚：

System.InvalidOperationException: The LINQ expression 'event => EntityShaperExpression: 
    WawAPI.Models.Event
    ValueBufferExpression: 
        ProjectionBindingExpression: EmptyProjectionMember
    IsNullable: False
.Guid == event.Guid' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'.

我不确定我在做什么错了，我感谢任何帮助。

原文

I want to update records in a table in my database using the code below:

context.Events
        .Where(eventDb => !events.Any(@event => eventDb.Guid == @event.Guid))
        .ToList()
        .ForEach(eventDb => eventDb.IsCurrent = false);

But every time on calling ToList() I'm getting the following error, which isn't clear to me:

System.InvalidOperationException: The LINQ expression 'event => EntityShaperExpression: 
    WawAPI.Models.Event
    ValueBufferExpression: 
        ProjectionBindingExpression: EmptyProjectionMember
    IsNullable: False
.Guid == event.Guid' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'.

I'm not sure what I'm doing wrong and I'd appreciate any help.

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成熟稳重的好男人 2025-02-06 20:07:42

我认为问题在于您要求SQL Server在Events上执行.yany（）操作，这大概是某种内存中的C＃object，并且不使用存在于SQL Server上，太复杂了，无法发送到SQL。

如果将GUID从Events提取到一个简单的字符串列表中，则可以简单地将其发送到SQL。您还需要稍微更改LINQ查询，但我认为这将为您提供所需的结果。

var eventGuids = events.select(a=>a.Guid).ToList();

context.Events
        .Where(eventDb => !eventGuids.Contains(event.Guid))
        .ToList()
        .ForEach(eventDb => eventDb.IsCurrent = false);

I think the problem is that you are asking the SQL server to perform a .Any() operation on events which is presumably some sort of in-memory C# object and does not exist on the SQL server and is too complicated to be sent to SQL.

If you extract the Guids from events into a simple list of strings, then that could be simple enough to send to sql. You also need to change your linq query slightly, but I think this will give you the results you are looking for.

var eventGuids = events.select(a=>a.Guid).ToList();

context.Events
        .Where(eventDb => !eventGuids.Contains(event.Guid))
        .ToList()
        .ForEach(eventDb => eventDb.IsCurrent = false);

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