[英]LINQ select in C# dictionary
我有 C# 中的下一個字典
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);
是否有可能在 LINQ select 的幫助下獲得所有“valueTitle”?
更新:抱歉,我應該先寫 - 我需要從 exitDictionary 中獲取結果,而不是從 subList
如果您按fieldname1
值搜索,請嘗試以下操作:
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();
如果您正在查看subDictionary
值的類型( Dictionary<string, object>
明確),您可以這樣做:
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();
兩種選擇都會返回:
title1
title2
title3
title1
title2
title3
一種方法是首先使用SelectMany
將列表展平:
subList.SelectMany(m => m).Where(k => k.Key.Equals("valueTitle"));
這將返回與您的鍵valueTitle
匹配的所有值
subList.SelectMany(m => m).Where(kvp => kvp.Key == "valueTitle").Select(k => k.Value).ToList();
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();
這也有效,並且易於理解。
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