Function serde_with::rust::deserialize_ignore_any

pub fn deserialize_ignore_any<'de, D: Deserializer<'de>, T: Default>(
    deserializer: D
) -> Result<T, D::Error>

Deserialize any value, ignore it, and return the default value for the type being deserialized.

This function can be used in two different ways:

1. It is useful for instance to create an enum with a catch-all variant that will accept any incoming data.
2. untagged enum representations do not allow the other annotation as the fallback enum variant. With this function you can emulate an other variant, which can deserialize any data carrying enum.

Note: Using this function will prevent deserializing data-less enum variants. If this is a problem depends on the data format. For example, deserializing "Bar" as an enum in JSON would fail, since it carries no data.

Examples

Deserializing a heterogeneous collection of XML nodes

When serde-xml-rs deserializes an XML tag to an enum, it always maps the tag name to the enum variant name, and the tag attributes and children to the enum contents. This means that in order for an enum variant to accept any XML tag, it both has to use #[serde(other)] to accept any tag name, and #[serde(deserialize_with = "deserialize_ignore_any")] to accept any attributes and children.

use serde_with::rust::deserialize_ignore_any;

#[derive(Deserialize)]
#[serde(rename_all = "lowercase")]
enum Item {
    Foo(String),
    Bar(String),
    #[serde(other, deserialize_with = "deserialize_ignore_any")]
    Other,
}

// Deserialize this XML
r"
<foo>a</foo>
<bar>b</bar>
<foo>c</foo>
<unknown>d</unknown>
"

// into these Items
vec![
    Item::Foo(String::from("a")),
    Item::Bar(String::from("b")),
    Item::Foo(String::from("c")),
    Item::Other,
]

Simulating an other enum variant in an untagged enum

use serde_with::rust::deserialize_ignore_any;

#[derive(Deserialize)]
#[serde(untagged)]
enum Item {
    Foo{x: u8},
    #[serde(deserialize_with = "deserialize_ignore_any")]
    Other,
}

// Deserialize this JSON
json!([
    {"y": 1},
    {"x": 1},
])

// into these Items
vec![Item::Other, Item::Foo{x: 1}]