我有一个以 JSON 格式返回请求的服务器。当尝试解析数据时，我总是收到“尾随字符”错误。仅当从邮递员获取 JSON 时才会发生这种情况
let type_of_request = parsed_request[1];
let content_of_msg: Vec<&str> = msg_from_client.split("\r\n\r\n").collect();
println!("{}", content_of_msg[1]);
// Will print "{"username":"user","password":"password","email":"dwadwad"}"
let res: serde_json::Value = serde_json::from_str(content_of_msg[1]).unwrap();
println!("The username is: {}", res["username"]);
从邮递员获取数据时会发生这种情况：
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error("trailing characters", line: 1, column: 60)', src\libcore\result.rs:997:5
但是当 Rust 中有字符串时：
let j = "{\"username\":\"user\",\"password\":\"password\",\"email\":\"dwadwad\"}";
let res: serde_json::Value = serde_json::from_str(j).unwrap();
println!("The username is: {}", res["username"]);
它就像一个魅力：
The username is: "user"
编辑：显然，当我将消息读入缓冲区并将其转换为字符串时，它保存了缓冲区具有的所有 NULL 字符，这些字符当然是尾随字符。
查看 serde json代码，可以在相关 ErrorCode 枚举元素上方找到以下注释：
/// JSON has non-whitespace trailing characters after the value.
TrailingCharacters,
因此，正如错误代码所暗示的那样，您有一些不是空格的尾随字符。在你的片段中，你说：
println!("{}", content_of_msg[1]);
// Will print "{"username":"user","password":"password","email":"dwadwad"}"
如果您将打印输出逐字复制并粘贴到此处，我会注意到，我不希望输出包含在前导引号和尾随引号中。这些是您自己添加的还是印刷内容的一部分？如果它们被打印出来，我怀疑这就是你问题的根源。
编辑：
事实上，我几乎可以使用 Rust 中带有前导/尾随引号的原始字符串来重新创建它：
extern crate serde_json;
#[cfg(test)]
mod tests {
#[test]
fn test_serde() {
let s =
r#""{"username":"user","password":"password","email":"dwadwad"}""#;
println!("{}", s);
let _res: serde_json::Value = serde_json::from_str(s).unwrap();
}
}
通过收益运行它cargo test：
test tests::test_serde ... FAILED
failures:
---- tests::test_serde stdout ----
"{"username":"user","password":"password","email":"dwadwad"}"
thread 'tests::test_serde' panicked at 'called `Result::unwrap()` on an `Err` value: Error("trailing characters", line: 1, column: 4)', src/libcore/result.rs:997:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
failures:
tests::test_serde
请注意，我的打印输出还包括前导/尾随引号，并且我也收到错误TrailingCharacter，尽管是在不同的列中。
编辑2：
根据您自己添加的包装引号的评论，您已经获得了一个已知的好字符串（您在 Rust 中定义的字符串），以及您认为应该匹配但不匹配的字符串（来自 Postman 的字符串） ）。
这是一个数据问题，所以我们应该检查数据。您可以调整以下代码来检查正确的字符串与其他字符串：
#[test]
fn test_str_comp() {
// known good string we'll compare against
let good =
r#"{"username":"user","password":"password","email":"dwadwad"}"#;
// lengthened string, additional characters
// also n and a in username are transposed
let bad =
r#"{"useranme":"user","password":"password","email":"dwadwad"}abc"#;
let good_size = good.chars().count();
let bad_size = bad.chars().count();
for (idx, (c1, c2)) in (0..)
.zip(good.chars().zip(bad.chars()))
.filter(|(_, (c1, c2))| c1 != c2)
{
println!(
"Strings differ at index {}: (good: `{}`, bad: `{}`)",
idx, c1, c2
);
}
if good_size < bad_size {
let trailing = bad.chars().skip(good_size);
println!(
"bad string contains extra characters: `{}`",
trailing.collect::<String>()
);
} else if good_size > bad_size {
let trailing = good.chars().skip(bad_size);
println!(
"good string contains extra characters: `{}`",
trailing.collect::<String>()
);
}
assert!(false);
}
对于我的示例，这会导致失败：
test tests::test_str_comp ... FAILED
failures:
---- tests::test_str_comp stdout ----
Strings differ at index 6: (good: `n`, bad: `a`)
Strings differ at index 7: (good: `a`, bad: `n`)
bad string contains extra characters: `abc`
thread 'tests::test_str_comp' panicked at 'assertion failed: false', src/lib.rs:52:9
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
failures:
tests::test_str_comp