在实体框架在where子句中使用列表 [英] Using a List in a where clause in Entity Framework

问题描述

我试图通过一到多个表检索文档的ID。我想用一个列表在where子句中找到所有的ID是与列表中的每一个元素连接

I am trying to retrieve document id's over a one-to-many table. I want to use a List in the where clause to find all id's that are connected with every element in the list.

List<int> docIds = (from d in doc
                      where _tags.Contains(d.Tags)
                      select d.id).ToList<int>();

我知道必须包含不正确，但我不能工作了。如果我尝试一个foreach我无法工作，如何检查，如果文档中包含的所有标签。

I know that the contains must be incorrect but I can't work it out. If I try a foreach I can't work out how to check if the document contains all Tags.

推荐答案

如果你想要的所有的 d.Tags 应该是包含在 _tags 列表，你可以尝试：

If you want that all d.Tags should be in the included in the _tags list, you can try:

List<int> docIds = (from d in doc
                      where d.Tags.All(t => _tags.Contains(t))
                      select d.id).ToList<int>();

如果您希望 d.Tags 应包含所有项目从 _tags 您需要：

If you want that d.Tags should contain all the item from _tags you need:

List<int> docIds = (from d in doc
                      where _tags.All(t => d.Tags.Contains(t))
                      select d.id).ToList<int>();

但我不知道它是如何通过翻译EF所以也许你需要在评估它的SQL客户现场。

But I don't know how it translates to SQL by EF so maybe you need to evaluate it on the client site.

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