Generate pretty (indented) JSON with serde

Question

Using the serde_json crate, I can use

::serde_json::to_string(&obj) 

to serialize an object into a JSON string. The resulting JSON uses compact formatting, like:

{"foo":1,"bar":2} 

But how do I generate pretty/indented JSON? For example, I'd like to get this:

{   "foo": 1,   "bar": 2 } 

Answer 1

The serde_json::to_string_pretty function generates pretty-printed indented JSON.

#[macro_use] extern crate serde_json;  fn main() {     let obj = json!({"foo":1,"bar":2});     println!("{}", serde_json::to_string_pretty(&obj).unwrap()); } 

This approach defaults to 2 spaces of indentation, which happens to be what you asked for in your question. You can customize the indentation by using PrettyFormatter::with_indent.

#[macro_use] extern crate serde_json;  extern crate serde; use serde::Serialize;  fn main() {     let obj = json!({"foo":1,"bar":2});      let buf = Vec::new();     let formatter = serde_json::ser::PrettyFormatter::with_indent(b"    ");     let mut ser = serde_json::Serializer::with_formatter(buf, formatter);     obj.serialize(&mut ser).unwrap();     println!("{}", String::from_utf8(ser.into_inner()).unwrap()); }