LINQ 和 OR 标准

发布于 2024-12-01 07:00:27 字数 314 浏览 1 评论 0原文

如何以编程方式创建 EF 查询（带有 lambda 的扩展方法）。我了解和标准。这是伪代码：

var query = repository.Where(x => x.Name == "aName");

foreach(string filter in filters)
{
   query = query.Where(x => x.FilterValue.Contains(filter))
}

但我想要的不是 and 运算符。我想要一个 or 运算符。我该怎么做？如何在代码中创建复杂的条件树？

原文

how can I programmatically create an EF query (extension methods with lambda). I understand the and criteria. Here is the pseudo-code:

var query = repository.Where(x => x.Name == "aName");

foreach(string filter in filters)
{
   query = query.Where(x => x.FilterValue.Contains(filter))
}

But what I want is not an and operator. I would like an or operator. How do I do this? How can I create complex criteria Trees in code?

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小傻瓜 2024-12-08 07:00:27

http://www.albahari.com/nutshell/predicatebuilder.aspx

PrdicateBuilder 是一个不错的解决方案。但它很复杂，不太容易理解。请参阅评论中其他问题的链接。

还发现这很有用：有时从另一个方向来很方便：

string[] filter = {"A", "B"};
var returnValue = repository
                .Where(x => x.Name == "aName")
                .Where(x => filter.Any(f => (x.FilterValue).Contains(f)))
                .ToList();

http://www.albahari.com/nutshell/predicatebuilder.aspx

PrdicateBuilder is a nice solution. But it is complicated and not so easy to understand. See Link to other question in comment.

Also found this useful: Sometimes it is convenient to come from the other direction:

string[] filter = {"A", "B"};
var returnValue = repository
                .Where(x => x.Name == "aName")
                .Where(x => filter.Any(f => (x.FilterValue).Contains(f)))
                .ToList();

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