#[serde_as(as = "Option<OneOrMany<_>>")]#[skip_serializing_none] fails to deserialize with None

[apps4uco]

I have this code which fails. I believe it should be supported.

#[serde_as]
#[skip_serializing_none]
#[derive(Debug, PartialEq, Serialize, Deserialize)]
struct Demo {
    #[serde_as(as = "Option<OneOrMany<_>>")]
    contents: Option<Vec<String>>,
}

It serializes fine with a single element in a vector or multiple elements in a vector

It fails with an error when the contents are set to None

failures:

---- tests::vec_none stdout ----
None
Serialized ---
{}

Error: Message("missing field contents", Some(Pos { marker: Marker { index: 4, line: 2, col: 0 }, path: "." }))

Please find a test case attached.

Workaround: Dont specify #[skip_serializing_none]

test.txt

[jonasbb]

You need to add #[serde(default)] as an attribute to the contents field too. It is the normal behavior for serde to disable the special treatment regarding missing fields whenever a with annotation is added. The serde_as is equivalent to the with in this regard.

There is an issue to maybe change that in the future #185.

    #[serde_as(as = "Option<OneOrMany<_>>")]
    #[serde(default)]
    contents: Option<Vec<String>>,

I hope that helps.

[apps4uco]

Great that fixes it. Maybe it could be added as an example to the documentation.

Thanks ever so much