如何在LINQ中执行String.Replace？

Question

这是我想要做的但没有成功.我想打电话from x in list1和join y in list2 where regex.Match(x.Value).Success.完成这些步骤后,我需要打String.Replace两次电话x.Value.然后调用on和select运算符.我希望它看起来像第二个例子.如何实现这一目标？

这是我的列表的样子:

list1              list2
Name    Value      Name    Value
item.1  $(prod1)   prod1   prodVal1
item.2  $(prod2)   prod2   prodVal2
item.3  prod3      prod3   prodVal3

这是我的列表应该是这样的:

updatedList         
Name    Value     
item.1  prodVal1   
item.2  prodVal2       
item.3  prod3      

示例1(这是我目前拥有的):

foreach (var x in list1)
{
    Match match = reg.Match(x.Value);
    if (match.Success)
    {
        x.Value = x.Value.Replace("$(", "");
        x.Value = x.Value.Replace(")", "");
    }
}

var commonItems = from x in list1
                  join y in list2
                  on x.Value equals y.Name
                  //where regex.Match(x.Value).Success
                  select new { Item = x, NewValue = y.Value };

foreach (var x in commonItems)
{
    x.Item.Value = x.NewValue;
}

例2:

var commonItems = from x in list1
                  join y in list2
                  where regex.Match(x.Value).Success
                  //do x.Value.Replace("$(", "")
                  //do x.Value.Replace(")", "")
                  //then call
                  on x.Value equals y.Name
                  select new { Item = x, NewValue = y.Value };

foreach (var x in commonItems)
{
    x.Item.Value = x.NewValue;
}

Answer 1

如果我正确理解了您想要let在查询中使用的内容:

var commonItems = from x in list1
                  join y in list2
                  let newX = x.Value.Replace("$(", "").Replace(")", "")
                  where regex.Match(x.Value).Success
                 &&  newX == y.Name
                  select new { Item = newX, NewValue = y.Value };

Answer 2

你确定你需要Regex.Match吗？你可以在不使用它的情况下获得相同的结果，无论如何我添加了两个版本......

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在 1\xc2\xb0 版本中，您可以使用简单的 If 语句来检查值是否已更改

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NewValue = x.Value != x1 ? y.Value: x.Value \n

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示例代码

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给定这个类

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class MyClass\n{\n    public string Name { get; set; }\n    public string Value { get; set; }\n}\n

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。

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添加项目

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        var list1 = new List<MyClass>();\n        list1.Add(new MyClass { Name = "item.1", Value = "$(prod1)" } );\n        list1.Add(new MyClass { Name = "item.2", Value = "$(prod2)" });\n        list1.Add(new MyClass { Name = "item.3", Value = "prod3" });\n\n        var list2 = new List<MyClass>();\n        list2.Add(new MyClass { Name = "prod1", Value = "prodVal1" });\n        list2.Add(new MyClass { Name = "prod2", Value = "prodVal2" });\n        list2.Add(new MyClass { Name = "prod3", Value = "prodVal3" });\n

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获取常用列表

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        var q =  from x in list1\n                 let x1 = x.Value.Replace("$(", "").Replace(")", "")\n                join y in list2 on x1 equals y.Name\n                select new { \n                    Item = x.Name, \n                    NewValue = x.Value != x1 ? y.Value: x.Value \n                };\n\n\n        foreach (var s in q)\n        {\n            Console.WriteLine(s.Item + " " + s.NewValue);\n        }\n

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结果

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item.1 prodVal1\nitem.2 prodVal2\nitem.3 prod3\n

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PS：我认为你不需要Regex，但以防万一这个版本可以使用它。

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var q = from x in list1\n        let x1 = x.Value.Replace("$(", "").Replace(")", "")\n        join y in list2 on x1 equals y.Name\n        select new\n        {\n            Item = x.Name,\n            NewValue = Regex.Match(x.Value, x1).Success ? x.Value : y.Value\n        };\n

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