如何将 lambda 中的字符串转换为十进制？

发布于 2024-11-29 12:38:09 字数 459 浏览 0 评论 0原文

我有代码

    myEntities db = new myEntities();
    var query = from s in db.mytable select s;
    if (!String.IsNullOrEmpty(str))
    {
      query = query.Where(p => p.total == str);
    }

Here，“total”的类型是包含数字和字符的字符串，例如“14x56xz”。我想从“total”字符串中获取数字部分（例如1456）并将其转换为十进制数，有时需要将其转换为负数，使代码如下所示：

    query = query.Where(10 <= p => p.total <= 1000);

我编写了一个类处理它，但我不知道如何在Linq中调用这个处理方法。

原文

I have the code

    myEntities db = new myEntities();
    var query = from s in db.mytable select s;
    if (!String.IsNullOrEmpty(str))
    {
      query = query.Where(p => p.total == str);
    }

Here, the type of "total" is a string containing numbers and characters, e.g. "14x56xz". I want to get the number part (e.g. 1456) from the "total" string and convert it to a decimal number, sometimes with the need to turn it into a negative number, making the code look like this:

    query = query.Where(10 <= p => p.total <= 1000);

I have written a class to process it, but I don't know how to invoke this processing method in Linq.

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情感失落者 2024-12-06 12:38:09

只需在 lambda 中解析它即可。例如：

query = query.Where(10 <= p => decimal.Parse(p.total) <= 1000m);

当然，如果有任何方法可以改进数据模型，以便将逻辑数值存储为数字，那就更好了......

编辑：我想你会有在 LINQ to Entities 中将“14x56xz”转换为 1456 很困难。您也许可以在数据库端执行某些操作，以使用转换和正则表达式等公开计算列，但我不确定您是否能够以适当转换的方式在 LINQ 中表达这一点。

Just parse it in the lambda. For example:

query = query.Where(10 <= p => decimal.Parse(p.total) <= 1000m);

Of course, if there's any way you can improve your data model so that logically-numeric values are stored as numbers, that would be even better...

EDIT: I think you'll have a hard time converting "14x56xz" to 1456 in LINQ to Entities. You may be able to do something at the database side to expose a computed column using conversions and regular expressions etc, but I'm not sure that you'd be able to express that in LINQ in a way which will be converted appropriately.

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