c# Nested Dictionary, better alternative? best organize data across three classes

c#, dictionary

Solution

Typically you don't see the objects that contain values used as keys in this way. Usually you will identify some unique key on your object and use that as key and the object itself as the value. For example you could store `Person` objects in a `Dictionary` where the person's name is the key, and `Person` is the value.

Instead of nested Dictionaries, you should consider adding Collections to your objects. For example, you could add a `List<TrendyItem>` to `Trend` to maintain that relationship.

Here is an alternative way that you could organize the classes. I'm not exactly sure what the scope is of each of your collections, but this should give you another way to look at the problem.

public class Trend
{
    public string TrendName { get; set; }
    public string Description { get; set; }

    // This maintains the relationship between Trend and TrendyItem
    public List<TrendyItem> Items { get; set; }
}

public class Person
{
    public string PersonName { get; set; }
    public int PersonId { get; set; }
    public int aptitude { get; set; }

    // Each person will specifiy a "TrendyItem"
    public TrendyItem Choice { get; set; }
}

public class TrendyItem
{
    public string ItemName { get; set; }
    public string ItemId { get; set; }
}

public class TrendProfile
{
    // Change this to to a key value pair. The key will be how you uniquely identify (input) the Trend in
    //2) Input: Trend; Output: List of trendy items belonging to that trend.
    // For example TrendName
    public Dictionary<string, Trend> FavoriteTrendsOfYear;

    // Change this to to a key value pair. The key will be how you uniquely identify (input) the Person in
    // 1) Input: Person; Output: List of Person's choice on trendy items.
    // For example PersonName
    public Dictionary<string, Person> ActivePeopleThisYear;


    public List<TrendyItem> TrendyItemsThisYear; 
}

With that class structure, you can easily answer the questions in your post.

static void Main()
{
    TrendProfile trendProfile = new TrendProfile();

    trendProfile.FavoriteTrendsOfYear = new Dictionary<string, Trend> {        
        { "Pizza", new Trend() {
            TrendName = "Pizza",
            Description = "yum yum",
            Items = new List<TrendyItem> {
                new TrendyItem() {ItemName = "PotatoPizza1"},
                new TrendyItem() {ItemName = "PotatoPizza2"},
                new TrendyItem() {ItemName = "PotatoPizza3"}
            }
        }},
        { "Clothing", new Trend() {
            TrendName = "Clothing",
            Description = "ba yum",
            Items = new List<TrendyItem> {
                new TrendyItem() {ItemName = "PeplumSkirt1"},
                new TrendyItem() {ItemName = "PeplumSkirt2"},
                new TrendyItem() {ItemName = "PeplumSkirt3"}
            }
        }}
    };

    trendProfile.ActivePeopleThisYear = new Dictionary<string, Person> {
        { "Arnold Palmer", new Person() { PersonName = "Arnold Palmer", Choice = trendProfile.FavoriteTrendsOfYear["Pizza"].Items[1] }},
        { "Ken Hemingway", new Person() { PersonName = "Ken Hemingway", Choice = trendProfile.FavoriteTrendsOfYear["Clothing"].Items[2] }},
    };

    //1) Input: Person; Output: List of Person's choice on trendy items.
    string person = "Arnold Palmer";
    Console.WriteLine(trendProfile.ActivePeopleThisYear[person].Choice.ItemName);

    //2) Input: Trend; Output: List of trendy items belonging to that trend.
    string trend = "Clothing";
    foreach(TrendyItem item in trendProfile.FavoriteTrendsOfYear[trend].Items)
        Console.WriteLine(item.ItemName);

}

UPDATE

To share Trends across TrendProfiles, you could first create a "master" `List` or `Dictionary` of Trends. Then when building each of the TrendProfliles, you could pick the Trends out of the "master".

// "Master" list of trends
List<Trend> trends = new List<Trend> {
    new Trend() {
        TrendName = "Pizza",
        Description = "yum yum",
        Items = new List<TrendyItem> {
            new TrendyItem() {ItemName = "PotatoPizza1"},
            new TrendyItem() {ItemName = "PotatoPizza2"},
            new TrendyItem() {ItemName = "PotatoPizza3"}
        }
    },
    new Trend() {
        TrendName = "Clothing",
        Description = "ba yum",
        Items = new List<TrendyItem> {
            new TrendyItem() {ItemName = "PeplumSkirt1"},
            new TrendyItem() {ItemName = "PeplumSkirt2"},
            new TrendyItem() {ItemName = "PeplumSkirt3"}
        }
    }
};


TrendProfile trendProfile1 = new TrendProfile();

trendProfile1.FavoriteTrendsOfYear = new Dictionary<string, Trend> {        
    { trends[0].TrendName, trends[0] },
    { trends[1].TrendName, trends[1] }
};

TrendProfile trendProfile2 = new TrendProfile();

trendProfile2.FavoriteTrendsOfYear = new Dictionary<string, Trend> {
    { trends[1].TrendName, trends[1] }
};

Problem

Original source