C# 具有字符串操作和正则表达式的LINQ查询结果 上下文

我从数据库中检索站点列表，如下所示：

DashboardEntities dashboardDB = new DashboardEntities();

var sites = dashboardDB.Instances
    .Select(attr => new SiteModel
        {
            server = attr.server,
            pool = attr.pool,
            url = attr.url,
            version = attr.version,
            client = ???
        })
    .ToList();

return sites;

String client = "";

Regex rgx = new Regex(@"\.[a-z-./]+");
client = rgx.Replace(attr.url, "");

rgx = new Regex("formation-");
client = rgx.Replace(client, "");

对于客户端，我需要从url获取一个子字符串，如下所示：

DashboardEntities dashboardDB = new DashboardEntities();

var sites = dashboardDB.Instances
    .Select(attr => new SiteModel
        {
            server = attr.server,
            pool = attr.pool,
            url = attr.url,
            version = attr.version,
            client = ???
        })
    .ToList();

return sites;

String client = "";

Regex rgx = new Regex(@"\.[a-z-./]+");
client = rgx.Replace(attr.url, "");

rgx = new Regex("formation-");
client = rgx.Replace(client, "");

问题

---

如何在我的LINQ查询中使用正则表达式进行此字符串操作？

您不能以当前形式使用它。对于正则表达式部分，没有已知的SQL转换。但是，一旦调用.ToList，您可以将其添加为后续选择

...   .ToList()
      .Select(
          z => z.client = new Regex(@"\.[a-z-./]+")
               .Replace(z.attr.url, "").Replace("formation-", "")
      )

将其视为伪代码，但这种通用方法应该能够完成它。然后您只需要在初始选择中设置client=

---

编辑：作为旁注，组成部分实际上不需要是正则表达式。一个简单的字符串替换就足够了，而且速度更快。

您不能以当前的形式替换它。对于正则表达式部分，没有已知的SQL转换。但是，一旦调用.ToList，您可以将其添加为后续选择

...   .ToList()
      .Select(
          z => z.client = new Regex(@"\.[a-z-./]+")
               .Replace(z.attr.url, "").Replace("formation-", "")
      )

将其视为伪代码，但这种通用方法应该能够完成它。然后您只需要在初始选择中设置client=

---

编辑：作为旁注，组成部分实际上不需要是正则表达式。一个简单的字符串替换就足够了，而且速度更快。

不幸的是，您将无法将正则表达式处理逻辑直接发送到数据库；您需要从数据库中获取url，然后遍历列表以从url中获取客户机数据

DashboardEntities dashboardDB = new DashboardEntities();  
var sites = dashboardDB.Instances 
    .Select(attr => new SiteModel 
    { 
        server = attr.server, 
        pool = attr.pool, 
        url = attr.url, 
        version = attr.version, 
        client = attr.url    // load the url for further processing
    }) 
    .ToList();
// iterate over the list and get client data from the url
sites.ForEach(ite => item.client = GetSubstring(item.client)); 
return sites; 

其中GetSubstring方法封装了正则表达式处理逻辑

private string GetSubstring(string url)
{
    String client = "";        
    Regex rgx = new Regex(@"\.[a-z-./]+");        
    client = rgx.Replace(attr.url, "");        
    rgx = new Regex("formation-");        
    client = rgx.Replace(client, ""); 
    return client;
}

---

不幸的是，您将无法将正则表达式处理逻辑直接发送到数据库；您需要从数据库中获取url，然后遍历列表以从url中获取客户机数据

DashboardEntities dashboardDB = new DashboardEntities();  
var sites = dashboardDB.Instances 
    .Select(attr => new SiteModel 
    { 
        server = attr.server, 
        pool = attr.pool, 
        url = attr.url, 
        version = attr.version, 
        client = attr.url    // load the url for further processing
    }) 
    .ToList();
// iterate over the list and get client data from the url
sites.ForEach(ite => item.client = GetSubstring(item.client)); 
return sites; 

其中GetSubstring方法封装了正则表达式处理逻辑

private string GetSubstring(string url)
{
    String client = "";        
    Regex rgx = new Regex(@"\.[a-z-./]+");        
    client = rgx.Replace(attr.url, "");        
    rgx = new Regex("formation-");        
    client = rgx.Replace(client, ""); 
    return client;
}

---

也许有更好的方法，但是：

Regex rgx1 = new Regex(@"\.[a-z-./]+");
Regex rgx2 = new Regex("formation-");

DashboardEntities dashboardDB = new DashboardEntities();

var sites = dashboardDB.Instances
    .Select(attr => new SiteModel
        {
            server = attr.server,
            pool = attr.pool,
            url = attr.url,
            version = attr.version,
            client = rgx2.Replace(rgx1.Replace(attr.url,""),"")
        })
    .ToList();

return sites;

---

也许有更好的方法，但是：

Regex rgx1 = new Regex(@"\.[a-z-./]+");
Regex rgx2 = new Regex("formation-");

DashboardEntities dashboardDB = new DashboardEntities();

var sites = dashboardDB.Instances
    .Select(attr => new SiteModel
        {
            server = attr.server,
            pool = attr.pool,
            url = attr.url,
            version = attr.version,
            client = rgx2.Replace(rgx1.Replace(attr.url,""),"")
        })
    .ToList();

return sites;

---

第二次替换甚至不需要正则表达式。可以使用静态重载将其作为单个表达式执行：

client = Regex.replace(attr.url, @"\.[a-z-./]+", "").Replace("formation-", "")

---

第二次替换甚至不需要正则表达式。可以使用静态重载将其作为单个表达式执行：

client = Regex.replace(attr.url, @"\.[a-z-./]+", "").Replace("formation-", "")

---

根据Guffa和RePierre的说法：

DashboardEntities dashboardDB = new DashboardEntities();

var sites = dashboardDB.Instances
    .Select(attr => new SiteModel
        {
            url = attr.url,
            server = attr.server,
            pool = attr.pool,
            version = attr.version,
            client = attr.url
        })
    .ToList();

sites.ForEach(attr => attr.client = Regex.Replace(attr.client, @"\.[a-z-./]+", "").Replace("formation-", ""));

---

根据Guffa和RePierre的说法：

DashboardEntities dashboardDB = new DashboardEntities();

var sites = dashboardDB.Instances
    .Select(attr => new SiteModel
        {
            url = attr.url,
            server = attr.server,
            pool = attr.pool,
            version = attr.version,
            client = attr.url
        })
    .ToList();

sites.ForEach(attr => attr.client = Regex.Replace(attr.client, @"\.[a-z-./]+", "").Replace("formation-", ""));

---

一种方法是将其设置为attr.url，然后在LINQ执行必要的替换后迭代列表？一种方法是将其设置为attr.url，然后在LINQ执行必要的替换后迭代列表？