rustHow to write struct to json file in Rust

Writing a struct to a JSON file in Rust is a simple process. The following example code block shows how to do this:

use serde::{Serialize, Deserialize};
use serde_json::{Result, Value};

#[derive(Serialize, Deserialize)]
struct Person {
    name: String,
    age: u8,
    phones: Vec<String>,
}

fn main() -> Result<()> {
    let p = Person {
        name: String::from("John"),
        age: 30,
        phones: vec![String::from("+44 1234567"), String::from("+44 2345678")],
    };

    let j = serde_json::to_string(&p)?;

    println!("{}", j);

    let mut file = std::fs::File::create("person.json")?;
    serde_json::to_writer_pretty(&mut file, &p)?;

    Ok(())
}

The output of the example code is:

{
  "name": "John",
  "age": 30,
  "phones": [
    "+44 1234567",
    "+44 2345678"
  ]
}

The code consists of the following parts:

1. use serde::{Serialize, Deserialize}; - imports the Serialize and Deserialize traits from the serde crate.
2. #[derive(Serialize, Deserialize)] - derives the Serialize and Deserialize traits for the Person struct.
3. let p = Person { ... } - creates an instance of the Person struct.
4. let j = serde_json::to_string(&p)?; - serializes the Person struct to a JSON string.
5. let mut file = std::fs::File::create("person.json")?; - creates a file called person.json.
6. serde_json::to_writer_pretty(&mut file, &p)?; - serializes the Person struct to the person.json file.

Helpful links

• serde
• serde_json

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