How to use Serde to (de)serialize a tuple struct from JSON named values instead of an array?

Question

I have a JSON object:

{ "min": 2, "max": 15 }

I'd like to parse it to this tuple struct:

#[derive(Serialize, Deserialize, Debug)]
struct TeamSize(pub i64, pub i64);
#[derive(Serialize, Deserialize, Debug)]
struct Match {
    size: TeamSize,
}

The current Serde serialization mechanism does not seem to provide the functionality of (de)serializing a tuple structure from named values instead of an array.

The generated (de)serialization mechanism expects the following:

{"size": [2, 15]}

I've tried to use Serde attributes, but I can't find one that does what I want:

#[derive(Serialize, Deserialize, Debug)]
pub struct TeamSize(
    #[serde(rename = "min")]
    pub i64,
    #[serde(rename = "max")]
    pub i64
);

How to parse it? Should I implement everything by myself?

I've opened an issue on the Serde repository .

Answer 1

#[derive(Serialize, Deserialize, Debug)]
pub struct TeamSize(
    #[serde(rename = "min")]
    pub i64,
    #[serde(rename = "max")]
    pub i64
);

is not valid code, the Serde rename attribute only renames what is being serialized and deserialized, it does not change your code. In a tuple struct (your first one), you can (and must) omit names because you simply access them via self.0 and self.1, but a struct doesn't have a first or a second field, so you must add a name to them.

Like so:

#[derive(Serialize, Deserialize, Debug)]
pub struct TeamSize {
    pub max: i64,
    pub min: i64,
};

Since the name of your attribute is the name of the JSON property (both min and max ), you do not need to use serde(rename) . You would have needed it if your Rust struct used the fields value_max and value_min but your JSON still used max and min .

If you absolutely want to parse it to a tuple struct, you must implement Serialize and Deserialize for your custom struct yourself. I don't think it's worth the hassle though, just switch to a struct instead of a tuple struct.