flatten and flatten_ref methods on ActiveValue

[PacificBird]

Closes #3145

[Huliiiiii]

Why not just:

impl<V> ActiveValue<Option<V>>
where
    V: Into<Value> + Nullable, 
{
...
}

[Huliiiiii]

Naming them as_option and into_option might be better.

[PacificBird]

Why not just:

impl<V> ActiveValue<Option<V>>
where
    V: Into<Value> + Nullable, 
{
...
}

This requires specialization afaik. The impl<V> ActiveValue<V> gives a conflicting implementation as far as the compiler is currently concerned.

[PacificBird]

Naming them as_option and into_option might be better.

That's definitely shorter and nicer.

[Huliiiiii]

Why not just:

impl<V> ActiveValue<Option<V>>
where
    V: Into<Value> + Nullable, 
{
...
}

This requires specialization afaik. The impl<V> ActiveValue<V> gives a conflicting implementation as far as the compiler is currently concerned.

Implementing it on Option<V> instead of V works correctly. (on my machine)

impl<V> ActiveValue<Option<V>>
where
    V: Into<Value> + Nullable,
{
    pub fn as_option(&self) -> Option<&V> {
        self.try_as_ref().and_then(Option::as_ref)
    }
 
    pub fn into_option(self) -> Option<V> {
        match self {
            Self::Set(value) | Self::Unchanged(value) => value,
            Self::NotSet => None,
        }
    }
}