LiteDb簡單key-value pair存法

LiteDb是C#上簡單的NoSql資料庫，不過想用一個collection來存不同型別的key-value pair就略顯麻煩。

好在LiteDb本身有提供schema-less的用法，詳細可參閱Collections - LiteDB :: A .NET embedded NoSQL database。

再略微調整一下，就可以撰寫一個通用的key-value pair存法。

Base class如下

public class KeyValueRepository
{
    public KeyValueRepository(ILiteCollection<BsonDocument> collection)
    {
        _collection = collection;
    }

    private ILiteCollection<BsonDocument> _collection;

    protected void SetValue(string key, object? value)
    {
        _collection.Upsert(new BsonDocument { ["_id"] = key, ["Value"] = BsonMapper.Global.Serialize(value) });
    }

    protected T? GetValue<T>(string key)
    {
        return BsonMapper.Global.Deserialize<T>(_collection.FindById(key)?["Value"]);
    }
}

繼承後，要宣告不同的type就比較方便了。

public class MyRepository : KeyValueRepository
{
    public MyRepository(ILiteCollection<BsonDocument> collection) : base(collection) { }

    public int A
    {
        get => GetValue<int>(nameof(A));
        set => SetValue(nameof(A), value);
    }

    public string? B
    {
        get => GetValue<string>(nameof(B));
        set => SetValue(nameof(B), value);
    }

    public List<int>? C
    {
        get => GetValue<List<int>>(nameof(C));
        set => SetValue(nameof(C), value);
    }

    public Dictionary<string, int>? D
    {
        get => GetValue<Dictionary<string, int>>(nameof(D));
        set => SetValue(nameof(D), value);
    }

    public Custom? E
    {
        get => GetValue<Custom>(nameof(E));
        set => SetValue(nameof(E), value);
    }
}

public class Custom
{
    public int Haha { get; set; }
    public string Hoho { get; set; }
}

最後用起來的樣子

using LiteDB;

// Open database (or create if doesn't exist)
using var ms = new MemoryStream();
using var db = new LiteDatabase(ms);
// Get a collection (or create, if doesn't exist)
var col = db.GetCollection<BsonDocument>("trytrysee");
var data = new MyRepository(col);

data.A = 123;
data.B = "123456";
data.C = new List<int> { 1, 3, 5, 7, 9 };
data.D = new Dictionary<string, int> { ["hello"] = 123, ["world"] = 456, };
data.E = new Custom { Haha = 777, Hoho = "Hoho" };
Console.WriteLine(data.A);
Console.WriteLine(data.B);
Console.WriteLine(data.C.Select(v => v.ToString()).Join(","));
Console.WriteLine(data.D.Select(v => $"{v.Key}:{v.Value}").Join(","));
Console.WriteLine($"Haha:{data.E.Haha}, Hoho:{data.E.Hoho}");