从字典中检索值 <string, List<string> &gt;

Question

I have dictionary with keys containing a list of strings.

Dictionary<string, List<string>> keyValueListDict=new Dictionary <string,List<string>>();
List<string>valueList = new List<string>();

My keyValueListDict is filled with unique keys and valueLists. For each dictionary entry, I need to output the key followed by the contents of the list (value).

Update: I think the problem is coming from entering the values So i am retrieving an object from my db

foreach(object)
{
  key=object.key;
  foreach(string value in object.othercomponent)
  {
    list.add(value);
  }
  keyValueListDict.add(key,list);
  list.clear();
}

The count for the values in the list resets to 0 everytime I clear the list so I can fill it for the next object, but I can't figure out how to avoid this

Answer 1

尝试这个：

var valueList = keyValueListDict.SelectMany(kvp => kvp.Value).ToList();

Answer 2

This is the basic approach to iterate over a dictionary:

var keyValueListDict = new Dictionary<string, List<string>>() {
    {"fookey", {"foo", "bar", "baz"}},
    {"barkey", {"bar", "baz", "foo"}},
    {"bazkey", {"baz", "foo", "bar"}}
};
foreach(var entry in keyValueListDict) {
    string key = entry.Key;
    List<string> values = entry.Value;
    //Console.WriteLine(key + " => " + values);
    //Console.WriteLine(key + " => [" + string.Join(", ", values) + "]");
}

Answer 3

Try something like this to create one output string of the dictionary's entry key followed by the combined values.

public string GetOutputString(KeyValuePair<string, List<string>> kvp)
{
    string separator = ", ";  //you can change this if needed (maybe a newline?)
    string outputString = kvp.Key + " " + String.Join(separator, kvp.Value);
    return outputString;
}

If you only had the key (and not the entire KeyValuePair ), you could create a copy from your dictionary with something like (see also this question about getting a KeyValuePair directly from a dictionary)

var kvp = new KeyValuePair<string, List<string>>(key, keyValueListDict[key]);

If you needed to output the entire dictionary, you could do something like this:

foreach (var kvp in keyValueListDict)
{
    string output = GetOutputString(kvp);
    //print output, write to file etc.
}

Working .NET fiddle

Answer 4

Try this:

 foreach (var key in dictionary.Keys)
 {
    var tmp = string.Empty;
    foreach (var value in dictionary[key])
    {
       tmp +=value """";
       System.Console.WriteLine(tmp );
    }
 }

Answer 5

I has this problem today, and I didn't like being forced to change my data structure, I really wanted to maintain the List<string> . This worked for me.

var reportTabGridItems = expectedReportTabsWithReportItems.Where(x => x.Key == reportTabName).Select(x => x.Value).FirstOrDefault();

I just wanted one row, therefore I tacked on the FirstOrDefault() to the end since the last select will bring back a list of list<string> and I just want one (or null if not found).

Hope this helps you.