C# C字典中的LINQ选择

我有下一本C语言词典

Dictionary<string, object> subDictioanry = new Dictionary<string, object>();

List<Dictionary<string, string>> subList = new List<Dictionary<string, string>>();

subList.Add(new Dictionary<string, string>(){
    {"valueLink", "link1"},
    {"valueTitle","title1"}
});
subList.Add(new Dictionary<string, string>(){
    {"valueLink", "link2"},
    {"valueTitle","title2"}
});
subList.Add(new Dictionary<string, string>(){
    {"valueLink", "link3"},
    {"valueTitle","title3"}
});

subDictioanry.Add("title", "title");
subDictioanry.Add("name", "name");
subDictioanry.Add("fieldname1", subList);

Dictionary<string, object> exitDictionary = new Dictionary<string, object>();
exitDictionary.Add("first", subDictioanry);
exitDictionary.Add("second", subDictioanry);

是否可以在LINQ select的帮助下获取所有valueTitle

更新：

---

抱歉，我应该先写它-我需要从exitDictionary而不是从subList获取结果这将返回与您的key valueTitle匹配的所有值

---

一种方法是首先使用SelectMany将列表展平：

---

如果要按fieldname1值搜索，请尝试以下操作：

var r = exitDictionary
   .Select(i => i.Value).Cast<Dictionary<string, object>>()
   .Where(d => d.ContainsKey("fieldname1"))
   .Select(d => d["fieldname1"]).Cast<List<Dictionary<string, string>>>()
   .SelectMany(d1 => 
       d1
        .Where(d => d.ContainsKey("valueTitle"))
        .Select(d => d["valueTitle"])
        .Where(v => v != null)).ToList();

两种选择都将返回：

title1
title2
title3
title1
title2
title3

---

这同样有效，并且易于理解。

这是错误的。kvp将不是一个KeyValuePair，而是一个字典。您缺少了一个用于展平列表的SelectMany。如果您使用类而不是字典，这将更容易进行推理。只是说说而已。

var r = exitDictionary
   .Select(i => i.Value).Cast<Dictionary<string, object>>()
   .Where(d => d.ContainsKey("fieldname1"))
   .Select(d => d["fieldname1"]).Cast<List<Dictionary<string, string>>>()
   .SelectMany(d1 => 
       d1
        .Where(d => d.ContainsKey("valueTitle"))
        .Select(d => d["valueTitle"])
        .Where(v => v != null)).ToList();

var r = exitDictionary
   .Select(i => i.Value).Cast<Dictionary<string, object>>()
   .SelectMany(d=>d.Values)
   .OfType<List<Dictionary<string, string>>>()
   .SelectMany(d1 => 
       d1
        .Where(d => d.ContainsKey("valueTitle"))
        .Select(d => d["valueTitle"])
        .Where(v => v != null)).ToList();

title1
title2
title3
title1
title2
title3

var res = exitDictionary
            .Select(p => p.Value).Cast<Dictionary<string, object>>()
            .SelectMany(d => d)
            .Where(p => p.Key == "fieldname1")
            .Select(p => p.Value).Cast<List<Dictionary<string,string>>>()
            .SelectMany(l => l)
            .SelectMany(d=> d)
            .Where(p => p.Key == "valueTitle")
            .Select(p => p.Value)
            .ToList();