Bind dictionary value by key

[Ghostbird]

I've got a dictionary representing a semi-dynamic object. I want to bind to the Icon property.
Aside from the fact that this could be modelled much more elegantly, I'm sure it's possible in XAML to bind to a dictionary key, but I don't know the syntax.

The data has this structure:

{
  "Properties": {
    "Icon": "person-outline"
  }
}

Here the root binding context is a proper class, but Properties is an IDictionary<string, object>.

I tried binding to Properties[Icon] but that didn't work.
Does anyone know how this should be done?

[masterofdaemon]

it works for me like this:
public Dictionary<string, Color> ObservableParameters { get => Parameters; set { SetProperty(Parameters, value, this, (u, n) => u.Parameters = n); } }

but my keys is DateTime, can anyone help with binding?
BackgroundColor="{Binding BindingContext.ObservableParameters[DateTime.Day-DateTime.Month], Source={x:Reference This}}" it works only with key like [9-10]

[Ghostbird]

I don't see how that would work. It seems like a convoluted way of what I already have. It would more properly be written as:

private IDictionary<string, Color> parameters = new();
public IDictionary<string, Color> ObservableParameters {
  get => parameters;
  set => SetProperty(ref parameters, value);
}

Code technically I don't see how using the four parameter overload that passes a model and callback would help, except it makes it so that you don't have to use the ref keyword. AFAIK the only reason why you'd do that is if Parameters is a C# property, because then you can't use ref. However if you that, you've got bigger problems, since your binding won't update if you write directly to Parameters. This property pattern should always be backed by a private member that is never accessed outside of this pattern. Hence I used that approach.

Functionally this makes it possible to bind to the dictionary itself, but won't help when trying to bind to a dictionary entry, since there's no code that interacts with those.

[masterofdaemon]

Yes, i need to make work days the different color:

` WorkDays.Add(new DateTime(2023, 2, 11));

        WorkDays.Add(new DateTime(2023, 2, 12));

        foreach (var day in Calendar.Days)

        {

            if (WorkDays.Contains(day.DateTime))

            {

                Parameters.Add($"{day.DateTime.Day}-{day.DateTime.Month}-{day.DateTime.Year}", Color.FromArgb("#00f"));

            }
            else

            {
                Parameters.Add($"{day.DateTime.Day}-{day.DateTime.Month}-{day.DateTime.Year}", Color.FromArgb("#f00"));

            }
        }`

but i can't bind that dates in xaml