Search for a value in List<Dictionary<string, object>>

问题

I have a List< Dictionary < string, object >> variable as follows.

private static List<Dictionary<string, object>> testData = new List<Dictionary<string, object>>(100);

// Just Sample data for understanding.
for (int i = 0; i < 100; i++)
{
    var test = new Dictionary<string, object>
        {
            { "aaa", "aaa" + i % 4 },
            { "bbb", "bbb" + i % 4 },
            { "ccc", "ccc" + i % 4 },
            { "ddd", "ddd" + i % 4 },
            { "eee", "eee" + i % 4 },
            { "fff", "fff" + i % 4 },
            { "ggg", "ggg" + i % 4 },
            { "hhh", "hhh" + i % 4 },
            { "iii", "iii" + i % 4 }
        };
    testData.Add(test);
}

I want to search for a list of key,value in the Dictionary and return the List< Dictionary < string, object >> contains the searchPattern I passed.

Dictionary<string, object> searchPattern = new Dictionary<string, object>();
searchPattern .Add("aaa", "aaa4");
searchPattern .Add("eee", "eee2");
searchPattern .Add("fff", "fff1");
searchPattern .Add("ddd", "ddd3");


public List<Dictionary<string, object>> SearchList(List<Dictionary<string, object>> testData, Dictionary<string, object> searchPattern)
{
    List<Dictionary<string, object>> result;

    // Search the list.

    return result;
}

Any other suggestions to search also appreciated. Many Thanks!!

回答1:

This will return the first dictionary in the list that contains all the key-value pairs in search pattern, or null if there isn't one.

public Dictionary<string, object> SearchList
(
    List<Dictionary<string, object>> testData,
    Dictionary<string, object> searchPattern
)
{
    return testData.FirstOrDefault(x => searchPattern.All(x.Contains));
}

If you want all the matches (not just the first one) use Where([...]).ToList() instead of FirstOrDefault([...]).

回答2:

Let me try:

    public static List<Dictionary<string, object>> SearchList(List<Dictionary<string, object>> testData, Dictionary<string, object> searchPattern)
    {
        return testData.Where(t =>
            {
                bool flag = true;
                foreach (KeyValuePair<string, object> p in searchPattern)
                {
                    if (!t.ContainsKey(p.Key) || !t[p.Key].Equals(p.Value))
                    {
                        flag = false;
                        break;
                    }
                }
                return flag;
            }).ToList();

    }

OR

    public static List<Dictionary<string, object>> SearchList(List<Dictionary<string, object>> testData, Dictionary<string, object> searchPattern)
    {
        return testData
                  .Where(t => searchPattern.All(p => t.ContainsKey(p.Key) && 
                                                     t[p.Key].Equals(p.Value)))
                  .ToList();
    }

回答3:

If I understand you correctly:

var result = testData.Where(dic => searchPattern.All(dic.Contains))
                     .ToList();

回答4:

There are couple of ways of doing this. _Individuals1 = file1.fileIndividuals; _Individuals2 = file2.fileIndividuals;

    foreach (KeyValuePair<int, Individual> kvpInd in _Individuals1) 
    { 
        foreach (KeyValuePair<int, Individual> kvpInd2 in _Individuals2) 
        { 
            if (kvpInd.Value.name.name == kvpInd2.Value.name.name) 
            { 
                similarInds.Add(kvpInd.Key, kvpInd.Value); 
            } 
        } 
    } 

var similarInds = file1.fileIndividuals. 
Where(kv1 => file2.fileIndividuals.Any(kv2 => kv1.Value.name.name == kv2.Value.name.name)). 
ToDictionary(kv => kv.Key, kv => kv.Value); 

this will fail if you have duplicate values using linq you can do like this

回答5:

I agree with armen.shimoon, however something like this:

public static List<Dictionary<string, object>> SearchList(this List<Dictionary<string, object>> list,
        Dictionary<string, object> searchPattern)
    {
        return list.Where(item =>
            searchPattern.All(x => item.ContainsKey(x.Key) && 
                x.Value.Equals(item[x.Key])
            )).ToList();
    }

And then using like this:

    searchResult = testData.SearchList(searchPattern);

来源：https://stackoverflow.com/questions/12399212/search-for-a-value-in-listdictionarystring-object