CODEWITHSUNDEEP
c#grouping
Dev 404
Dev 404

Reputation: 1596

Group by key and value for List<Dictionary<string, object>>

I have a List<Dictionary<string, object>> that looks similar to the following:

var myList =
            new List<Dictionary<string, object>>
            {
                new Dictionary<string, object>
                {
                    { "Name", "Bob" },
                    { "Certification", "Certification A" },
                    { "Date", "10/1/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Bob" },
                    { "Certification", "Certification A" },
                    { "Date", "01/01/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Bob" },
                    { "Certification", "Certification B" },
                    { "Date", "10/5/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Joe" },
                    { "Certification", "Certification A" },
                    { "Date", "10/5/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Joe" },
                    { "Certification", "Certification B" },
                    { "Date", "10/5/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Joe" },
                    { "Certification", "Certification B" },
                    { "Date", "01/01/2022" }
                }
            };

I am needing to group by Name and Certification so that I end up with:

{
    new Dictionary<string, object>
    {
        { "Name", "Bob" },
        { "Certification", "Certification A" },
        { "Date", "10/1/2022" }
    },
    new Dictionary<string, object>
    {
        { "Name", "Bob" },
        { "Certification", "Certification B" },
        { "Date", "10/5/2022" }
    },
    new Dictionary<string, object>
    {
        { "Name", "Joe" },
        { "Certification", "Certification A" },
        { "Date", "10/5/2022" }
    },
    new Dictionary<string, object>
    {
        { "Name", "Joe" },
        { "Certification", "Certification B" },
        { "Date", "10/5/2022" }
    }
};

I'm completely stumped on how to get to that result so any guidance would be appreciated.

Upvotes: 0

Views: 343

Answers (1)

Guru Stron
Guru Stron

Reputation: 142843

You can just leverage the value tuples with their generated equality members:

var result = myList.GroupBy(d => (Name: d["Name"], Certification: d["Certification"]))
    .Select(g => g.First()) // apply ordering if needed
    .ToList();

Or the same with anonymous types:

var result = myList.GroupBy(d => new { Name = d["Name"], Certification = d["Certification"] })
    .Select(g => g.First()) // apply ordering if needed
    .ToList();

Note that this will require all dictionaries to have all members present and all values to correctly implement Equals and GetHashcode.

Also note that you can type your dictionaries as Dictionary<string, string>

Upvotes: 2

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