我使用Serde将具有十六进制值 0x400 的XML文件反序列化为一个字符串，我需要将它转换为值 1024 作为 u32 。
我是否需要实现 Visitor trait，这样我就可以将0x分开，然后从基本16解码400到基本10？如果是这样，我该怎么做，以便10个基本整数的反序列化保持不变？
解决方案 deserialize_with 属性最简单的解决方案是使用 Serde字段属性 deserialize_with 为您的字段设置自定义序列化功能。然后，您可以获取原始字符串并将其转换为适当的：
extern crate serde; ＃[macro_use] extern crate serde_derive; extern crate serde_json; 使用serde :: {Deserialize，Deserializer}; 使用serde :: de :: Error; $ b $ [b] [b] struct EtheriumTransaction {＃[serde（deserialize_with =from_hex）] account：u64，// hex amount：u64，//十进制} fn from_hex<'de，D>（解串器：D） - >结果< u64，D ::错误> 其中 D：反序列化器< de>， { let s：& str =反序列化::反序列化（反序列化器）？ //比这个更好的十六进制解码u64 :: from_str_radix（& s [2 ..]，16）.map_err（D :: Error :: custom）} fn main（）{ let raw = r＃{account：0xDEADBEEF，amount：100}＃; let transaction：EtheriumTransaction = serde_json :: from_str（raw）.expect（Could not derserialize）; assert_eq！（transaction.amount，100）; assert_eq！（transaction.account，0xDEAD_BEEF）; }playground $ b 实现 serde :: Deserialize 从这里开始，将它推广到自己的类型以允许重用它是一小步：
＃[derive（Debug，Deserialize）] struct EtheriumTransaction { account：Account，// hex amount：u64，// decimal $ b $＃[derive（Debug，PartialEq）] struct Account（u64）; impl<'de>反序列化<去>用于帐户{ fn反序列化< D>（反序列化器：D） - >结果< Self，D :: Error> 其中 D：反序列化器< de>， { let s：& str =反序列化::反序列化（反序列化器）？ //比这个更好的十六进制解码u64 :: from_str_radix（& s [2 ..]，16） .map（Account） .map_err（D： ：Error :: custom）} }playground
请注意，使用任何其他现有的Serde实现来解码。在这里，我们解码为一个字符串片段（ let s：& str = Deserialize :: deserialize（deserializer）？）。
此方法允许您添加或删除字段，因为内部反序列化类型可以根据需要进行任何操作。
另请参阅：
- 如何在使用Serde序列化期间转换字段？
I'm using Serde to deserialize an XML file which has the hex value 0x400 as a string and I need to convert it to the value 1024 as a u32.
Do I need to implement the Visitor trait so that I separate 0x and then decode 400 from base 16 to base 10? If so, how do I do that so that deserialization for base 10 integers remains intact?
解决方案The deserialize_with attribute
The easiest solution is to use the Serde field attribute deserialize_with to set a custom serialization function for your field. You then can get the raw string and convert it as appropriate:
extern crate serde; #[macro_use] extern crate serde_derive; extern crate serde_json; use serde::{Deserialize, Deserializer}; use serde::de::Error; #[derive(Debug, Deserialize)] struct EtheriumTransaction { #[serde(deserialize_with = "from_hex")] account: u64, // hex amount: u64, // decimal } fn from_hex<'de, D>(deserializer: D) -> Result<u64, D::Error> where D: Deserializer<'de>, { let s: &str = Deserialize::deserialize(deserializer)?; // do better hex decoding than this u64::from_str_radix(&s[2..], 16).map_err(D::Error::custom) } fn main() { let raw = r#"{"account": "0xDEADBEEF", "amount": 100}"#; let transaction: EtheriumTransaction = serde_json::from_str(raw).expect("Couldn't derserialize"); assert_eq!(transaction.amount, 100); assert_eq!(transaction.account, 0xDEAD_BEEF); }playground
Implement serde::DeserializeFrom here, it's a tiny step to promoting it to your own type to allow reusing it:
#[derive(Debug, Deserialize)] struct EtheriumTransaction { account: Account, // hex amount: u64, // decimal } #[derive(Debug, PartialEq)] struct Account(u64); impl<'de> Deserialize<'de> for Account { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>, { let s: &str = Deserialize::deserialize(deserializer)?; // do better hex decoding than this u64::from_str_radix(&s[2..], 16) .map(Account) .map_err(D::Error::custom) } }playground
Note how this can use any other existing Serde implementation to decode. Here, we decode to a string slice (let s: &str = Deserialize::deserialize(deserializer)?).
This method allows you to also add or remove fields as the "inner" deserialized type can do basically whatever it wants.
See also:
- How to transform fields during serialization using Serde?
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