c# - 替换字符串中的占位符

Question

我有如下字符串:

Insert into Emp(Id,Name,Number,Address) values({Id},"Abc",{Number},{Address});

在上面的字符串 {Id} 中，{Number} 和 {Address} 是我想用一些值替换的占位符。

我想要字符串中的占位符列表，并且我想轻松地将其替换为实际值。

输出应该是这样的:

Insert into Emp(Id,Name,Number,Address) values(123,'Abc',55668878,'test address');

Answer 1

如果您在变量中收到字符串，您应该自己进行插值

为此，您需要找到所有占位符并替换它们的值。您可以使用正则表达式执行此操作(如果占位符可以以数字开头，则可以简化)

{(?<placeholder>[a-z_][a-z0-9_]*?)}

下一个方法将执行此替换:

public static string Replace(string input, Dictionary<string, object> replacement)
{
    var regex = new Regex("{(?<placeholder>[a-z_][a-z0-9_]*?)}",
        RegexOptions.Compiled | RegexOptions.IgnoreCase);

    return regex.Replace(input, m =>
    {
        var key = m.Groups["placeholder"].Value;
        if (replacement.TryGetValue(key, out var value))
            return value.ToString();

        throw new Exception($"Unknown key {key}");
    });
}

用法:

var input = "Insert into Emp(Id,Name,Number,Address) values({Id},\"Abc\",{Number},{Address});";
var replaces = new Dictionary<string, object>
{
    {"Id", 123},
    { "Number", 55668878},
    {"Address", "\"test address\"" },
};

var result = Replace(input, replaces);
Console.WriteLine(result);

输出:

Insert into Emp(Id,Name,Number,Address) values(123,"Abc",55668878,"test address");