We will use serde and serde_json crate to parse string to object and dump object to json string.
This code contains:
- Read json string from file and parse string to object
- Use
json!macro to create Value object and use.to_string()function to dump object to string - Use
SerializeandDeserializetrait for self-defined struct so we can dump it to string - Use
serde_json::to_stringandserde_json::to_string_prettyto dump object to string
First let's create a config.json file for test reading, put it in the same level as the Cargo.toml, like this:
proj
|-- Cargo.toml
|-- config.json
|-- src
In config.json, put some sample json string:
{
"debug": true,
"name": "serdetest"
}
And in Cargo.toml file:
[dependencies]
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0.42"
Make sure features = ["derive"] exists [1], otherwise later in our code, #[derive(Serialize)] won't work.
Code in main.rs:
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};
use std::fs;
#[derive(Serialize, Deserialize)]
struct Person {
name: String,
score: i32,
}
fn main() {
// parse config file
let path = concat!(env!("CARGO_MANIFEST_DIR"), "/config.json");
let s = fs::read_to_string(path).unwrap();
let cfg: Value = serde_json::from_str(&s).unwrap();
println!("Config: debug {}", cfg["debug"]);
// json! macro
let bonus = 10;
let result = json!({
"name": "Bo",
"score": 92 + bonus,
});
println!("JSON!: {}", result.to_string());
println!("JSON! Pretty: {}", serde_json::to_string_pretty(&result).unwrap());
// serde_json to_string and to_string_pertty
let p = Person {name: "Bo".to_owned(), score: 92};
let serialized = serde_json::to_string(&p).unwrap();
println!("Person serialized: {}", serialized);
let serialized_pretty = serde_json::to_string_pretty(&p).unwrap();
println!("Person serialized pretty: {}", serialized_pretty);
}
Result:
Config: debug true
JSON!: {"name":"Bo","score":102}
JSON! Pretty: {
"name": "Bo",
"score": 102
}
Person serialized: {"name":"Bo","score":92}
Person serialized pretty: {
"name": "Bo",
"score": 92
}
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