How to define a behavior for each insert to dictionary c#? like write to the log each insert-CodePudding

I have a class that contains a Dictionary field. I would like to log each insert to the dictionary. What is the most elegant way to do that?

I tried to define a property of the dictionary, and to put the log in the set method:

private Dictionary<string, string> _myDictionary = new Dictionary<string, string>();

private Dictionary<string, string> MyDictionary
{
    get
    {
        return _myDictionary;
    }
    set
    {
        _logger.Trace($"MyDictionary.set: value = {value}");

        _myDictionary = value;
    }
}

but it is not relevant for an insert, only for an assignment for the dictionary reference. I would like to "catch" the set of a key-value like in the following operation, and log it:

MyDictionary["key"] = "some value";

How?

CodePudding user response：

You could create a class that derives from Dictionary<TKey, TValue> and replace the standard Add method and the indexer property adding some kind of logging before calling the base implementation

public class LoggedDictionary<TKey, TValue> : Dictionary<TKey, TValue>
{

    public new void Add(TKey key, TValue value)
    {
        // Replace with whatever logging method you use
        Console.WriteLine($"Add called {key} = {value}");
        base.Add(key,value);
    }

    public new TValue this[TKey key]
    {
        get
        {
            // Replace with whatever logging method you use
            Console.WriteLine("Get called");
            return base[key];
        }
        set
        {
            // Replace with whatever logging method you use
            Console.WriteLine($"Set called {key} = {value}");
            base[key] = value;
        }
    }
}

void Main()
{
    LoggedDictionary<string, string> logged = new LoggedDictionary<string, string>();
    logged.Add("test", "t1");
    logged["test"] = "t2";
}

If your intent is to log every action that changes the dictionary then you need to redefine also the Remove methods

public new bool Remove(TKey key)
{
    Console.WriteLine($"Remove called for {key}");
    return base.Remove(key);
}
public new bool Remove(TKey key, out TValue value)
{
    Console.WriteLine($"Remove called for {key}");
    return base.Remove(key, out value);
}