(Rust- JSON) 如何在 rust 中将 &str 转换为 JSON 响应？

Question

Hello I have a &str type variable. How can I convert it to json? for example I have &str

{"index":0,"name":"AB/CDE/FG/402/test_int4","sts":"on","time":"2021-06-05 03:28:24.044284300 UTC","value":8}

How can I convert this to json

{
"index": 0,
"name": "AB/CDE/FG/402/test_int4",
"sts": "on",
"time": "2021-06-05 03:28:24.044284300 UTC",
"value": 8 
}

is there anything like python json.loads() method available or something equivalent can be done in rust?

Answer 1

I dont know anything builtin, but this package can do it:

use tinyjson::{JsonParseError, JsonValue};

fn main() -> Result<(), JsonParseError> {
   let s = r#"
{
   "index":0,
   "name":"AB/CDE/FG/402/test_int4",
   "sts":"on",
   "time":"2021-06-05 03:28:24.044284300 UTC",
   "value":8
}
"#;
   let m: JsonValue = s.parse()?;
   println!("{:?}", m);
   Ok(())
}

Result:

Object({
   "value": Number(8.0),
   "index": Number(0.0),
   "name": String("AB/CDE/FG/402/test_int4"),
   "time": String("2021-06-05 03:28:24.044284300 UTC"),
   "sts": String("on")
})

https://docs.rs/tinyjson

Answer 2

There's a misconception here. JSON is a serialization format, its always a string. Your two blocks are both JSON and functionally identical. What json.loads() is deserialize it into a value that can be accessed and manipulated natively.

You probably want to use a serde_json::Value if you want to this JSON to be used generically.

use serde_json::Value;

fn main() {
    let input = r#"{"index":0,"name":"AB/CDE/FG/402/test_int4","sts":"on","time":"2021-06-05 03:28:24.044284300 UTC","value":8}"#;
    let mut object: Value = serde_json::from_str(input).unwrap();
    
    if let Some(name) = object.get_mut("name") {
        *name = "new name".into();
    }
    
    println!("{}", object);
}

{"index":0,"name":"new name","sts":"on","time":"2021-06-05 03:28:24.044284300 UTC","value":8}

Playground

Or, its typical to create a structure that reflects what the JSON is expected to be and deserialize into that type via serde :

use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize, Debug)]
struct Data {
    index: i32,
    name: String,
    sts: String,
    time: String,
    value: i32
}

fn main() {
    let input = r#"{"index":0,"name":"AB/CDE/FG/402/test_int4","sts":"on","time":"2021-06-05 03:28:24.044284300 UTC","value":8}"#;
    let mut object: Data = serde_json::from_str(input).unwrap();
    
    object.name = "new name".to_string();
    
    println!("{:#?}", object);
}

Data {
    index: 0,
    name: "new name",
    sts: "on",
    time: "2021-06-05 03:28:24.044284300 UTC",
    value: 8,
}

Playground