Question about flattening struct in place of key of map with Serde

[spitf1re]

Hello. I have the following structs:

struct Player {
    name: String,
}

struct Agent {
    name: String,
}
#[derive(Serialize)]
struct Match {
    agents: HashMap<Player, Agent>,
}

How can I make serde to flatten the keys and values when serializing/deserializing the Match? For example

Match {
  agents: HashMap::from([(Player { name: "Rb"}, Agent { name: "Killjoy"})])
}

should get serialized into

{ agents: {"Rb": "Killjoy" }}

and same with deserialization.

I have actually achieved the serializing part with implementing my own serializer, but deser seems more complicated, so I wanted to know if there's any easier way to do both.

(FYI: the serializer part is pretty easy:

impl Serialize for Player {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer {
        serializer.serialize_str(&self.name)
    }
}
impl Serialize for Agent {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer {
        serializer.serialize_str(&self.name)
    }
}

)

[H2CO3]

@spitf1re

but deser seems more complicated

Not really:

impl<'de> Deserialize<'de> for Player {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>
    {
        let name = String::deserialize(deserializer)?;
        Ok(Player { name })
    }
}

impl<'de> Deserialize<'de> for Agent {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>
    {
        let name = String::deserialize(deserializer)?;
        Ok(Agent { name })
    }
}

[spitf1re]

Yeah, thanks for this, seems easy enough! I saw visitor and stuff in the example in documentation.

But I actually solved the issue with #[serde(transparent)]. Marking the struct with this is exactly what I needed. Then usual derive just works the way I wanted.

[H2CO3]

@spitf1re

I saw visitor and stuff in the example in documentation.

That's only needed if you want to avoid creating an owned value (e.g. you don't want to create a String just to deserialize it into an enum variant and then throw it away). Otherwise, forwarding to other types' Deserialize is entirely possible and easy.