Attribute macro to skip serializing all fields of Option type

[dtolnay]

Some JSON workflows involve practically every piece of data being nullable and none of then being serialized when null. The Serde attributes in this situation can be verbose and distracting.

#[derive(Serialize)]
struct Data {
    id: u64,
    #[serde(skip_serializing_if = "Option::is_none")]
    a: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    b: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    c: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    d: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    e: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    f: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    g: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    h: Option<String>,
}

It would be better to have an attribute macro that finds all fields of type Option\<_> and inserts a skip_serializing_if attribute.

#[skip_serializing_null]
#[derive(Serialize)]
struct Data {
    id: u64,
    a: Option<String>,
    b: Option<String>,
    c: Option<String>,
    d: Option<String>,
    e: Option<String>,
    f: Option<String>,
    g: Option<String>,
    h: Option<String>,
}

Optionally consider supporting an attribute to annotate optional fields that always need to be serialized, even when null.

#[skip_serializing_null]
#[derive(Serialize)]
struct Data {
    id: u64,
    #[always]
    a: Option<String>,
    b: Option<String>,
    /* ... */
}

[jonasbb]

I'm tackling this issue over at https://github.com/jonasbb/serde_with/pull/46

EDIT: This feature is included in version 1.3.0 of serde_with.

[jonathan-s]

Looks like this feature is completed, no?

[Warfields]

???

[DrSensor]

I think this already shipped in the current crate serde_with. I've used it and it works as expected. The only thing missing is the documentation 🤔