Untyped JSON with Value in Rust

When the shape is unknown, Value and the json! macro handle it dynamically.

use serde_json::{json, Value};

fn main() -> Result<(), serde_json::Error> {
    let payload = json!({
        "lang": "sql",
        "tours": ["basics", "joins"],
        "steps": 45
    });

    println!("{}", payload["lang"].as_str().unwrap_or("?"));
    println!("{:?}", payload["steps"].as_u64());
    println!("{}", payload["missing"].is_null());

    let parsed: Value = serde_json::from_str(r#"{"ok":true}"#)?;
    println!("{:?}", parsed["ok"].as_bool());
    Ok(())
}

How it works

json! builds a Value with JSON-ish syntax.
Indexing returns Value::Null rather than panicking.
as_str and as_u64 attempt a typed read.

Keywords and builtins used here

Ok
Result
Value
fn
let
main
use

The run, in numbers

Lines: 17
Characters to type: 421
Tokens: 160
Three-star pace: 100 tpm

At the three-star pace of 100 tokens a minute, this run takes about 96 seconds.

Type this snippet

Step 2 of 3 in Deriving, step 2 of 11 in Serde & JSON.

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