您可以实施自定义Visitor
它忽略了序列的其余部分。请注意,必须消耗整个序列。这是一个重要的部分(尝试删除它,你会得到同样的错误):
// This is very important!
while let Some(IgnoredAny) = seq.next_element()? {
// Ignore rest
}
这是一个工作示例:
use std::fmt;
use serde::de::{self, Deserialize, Deserializer, IgnoredAny, SeqAccess, Visitor};
use serde::Serialize;
#[derive(Serialize, Debug)]
pub struct MyTuple(String, i32);
impl<'de> Deserialize<'de> for MyTuple {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: Deserializer<'de>,
{
struct MyTupleVisitor;
impl<'de> Visitor<'de> for MyTupleVisitor {
type Value = MyTuple;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("struct MyTuple")
}
fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
where
V: SeqAccess<'de>,
{
let s = seq
.next_element()?
.ok_or_else(|| de::Error::invalid_length(0, &self))?;
let n = seq
.next_element()?
.ok_or_else(|| de::Error::invalid_length(1, &self))?;
// This is very important!
while let Some(IgnoredAny) = seq.next_element()? {
// Ignore rest
}
Ok(MyTuple(s, n))
}
}
deserializer.deserialize_seq(MyTupleVisitor)
}
}
fn main() {
let two_elements = r#"["foo", 123]"#;
let three_elements = r#"["foo", 123, "bar"]"#;
let tuple: MyTuple = serde_json::from_str(two_elements).unwrap();
assert_eq!(tuple.0, "foo");
assert_eq!(tuple.1, 123);
let tuple: MyTuple = serde_json::from_str(three_elements).unwrap();
assert_eq!(tuple.0, "foo");
assert_eq!(tuple.1, 123);
}