Subscription handler

Question 1

I have so many classes like this in my solution but I’ve chosen this one just to show you guys what I mean by it.

In my solution I have lots of classes that just follow the same 2 classes exactly the same, except for the class name and for different purposes.

The issue is, I think I’m OP’ing it. Does something this simple, something I do with around 50 class pairs in my solution really need to take up 2 files and this much code?

It seems like it can be improved but I just can’t work out a well-driven way, someone said something about structs but I didn’t really look into it too much and it’s been too long to remember what else they said.

Is there some sort of layout or structure I can do to reduce the amount of code or the time it takes to code this? I feel like somethings staring me right in the face and I’m missing it.

The purpose of this class pair is to cache database information, store it in a dictionary and return it in case you need it later. It saves an extra call to the database every time I need to get something, and it’s just a lot easier to maintain and work with than constant database calls all over the place.

internal class SubscriptionHandler
{
    private readonly Dictionary<int, Subscription> _subscriptions;

    public SubscriptionHandler()
    {
        _subscriptions = new Dictionary<int, Subscription>();
    }

    public void Load()
    {
        using (var dbConnection = Program.Server.DatabaseHandler.Connection)
        {
            dbConnection.SetQuery("SELECT * FROM `subscriptions`;");

            using (var reader = dbConnection.ExecuteReader())
            {
                while (reader.Read())
                {
                    var subscriptionId = reader.GetInt32("id");
                    _subscriptions[subscriptionId] = new Subscription();
                }
            }
        }
    }

    public bool TryGetSubscriptionById(int subscriptionId, out Subscription subscription)
    {
        return _subscriptions.TryGetValue(subscriptionId, out subscription);
    }
}

internal class Subscription
{
    public int Id;
    public string Name;
    public string Badge;
    public int Credits;
    public int Pixels;
    public int Respects;

    public Subscription(int id, string name, string badge, int credits, int pixels, int respects)
    {
        Id = id;
        Name = name;
        Badge = badge;
        Credits = credits;
        Pixels = pixels;
        Respects = respects;
    }
}

Question 2

So you’re saying that you have a bunch of classes representing db rows, and need a WhateverHandler for each class?

Use generics.

https://msdn.microsoft.com/en-us/library/ms172192(v=vs.110).aspx
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/

The type is replaced whenever you need to use it, like so:

internal class Handler<T> where T : new()
{
    private readonly Dictionary<int, T> _rows;
    private readonly string _tableName;
    private Handler() {}
    public Handler(string tableName)
    {
        _rows = new Dictionary<int, T>();
        _tableName = tableName;
    }

    public void Load()
    {
        using (var dbConnection = Program.Server.DatabaseHandler.Connection)
        {
            dbConnection.SetQuery("SELECT * FROM `{0}`;".Format(tablename));

            using (var reader = dbConnection.ExecuteReader())
            {
                while (reader.Read())
                {
                    var rowId = reader.GetInt32("id");
                    _rows[rowId] = new T();
                }
            }
        }
    }

    public bool TryGetById(int rowId, out T row)
    {
        return _rows.TryGetValue(rowId, out row);
    }
}

edit: thanks @kuskmen for reminding me about the new() constraint

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