rust 28 lines · 8 steps

Trimming JSON output with serde attributes

How serde attributes control which struct fields appear in serialized JSON.

Explained by highlit
serde Intermediate serialization json attributes optional-fields data-modeling
1use serde::{Deserialize, Serialize};
2 
3#[derive(Debug, Serialize, Deserialize)]
4pub struct UserProfile {
5 pub id: u64,
6 pub username: String,
7 
8 #[serde(skip_serializing_if = "Option::is_none")]
9 pub display_name: Option<String>,
10 
11 #[serde(skip_serializing_if = "Option::is_none")]
12 pub bio: Option<String>,
13 
14 #[serde(skip_serializing_if = "Option::is_none", rename = "avatar")]
15 pub avatar_url: Option<String>,
16 
17 #[serde(skip_serializing_if = "Vec::is_empty", default)]
18 pub roles: Vec<String>,
19 
20 #[serde(skip_serializing_if = "Option::is_none")]
21 pub last_login: Option<chrono::DateTime<chrono::Utc>>,
22}
23 
24impl UserProfile {
25 pub fn to_json(&self) -> serde_json::Result<String> {
26 serde_json::to_string_pretty(self)
27 }
28}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1serde attributes let you shape the wire format without changing your Rust field names or types.
  2. 2Skipping empty optionals and collections keeps JSON output compact and free of null noise.
  3. 3Pairing skip_serializing_if with default makes a type both clean to emit and forgiving to parse.

Related explainers

rust 
use axum::{extract::{Path, State}, http::StatusCode, Json};
use dashmap::DashMap;
use serde::Serialize;
use std::sync::Arc;

Request coalescing in an Axum handler

caching concurrency request-coalescing
Advanced 8 steps
rust 
use std::net::Ipv4Addr;
use std::str::FromStr;
 
#[derive(Debug, Clone, Copy)]

Parsing and matching IPv4 CIDR ranges in Rust

bitwise-operations parsing error-handling
Intermediate 8 steps
typescript 
type CsvColumn<T> = {
  header: string;
  value: (row: T) => string | number | boolean | null | undefined;
};

Building a type-safe CSV writer in TypeScript

generics serialization escaping
Intermediate 7 steps
rust 
use std::sync::OnceLock;
 
static CRC_TABLE: OnceLock<[u32; 256]> = OnceLock::new();
 

Table-driven CRC32 with lazy init in Rust

checksums lazy-initialization lookup-tables
Intermediate 8 steps
rust 
use axum::{
    body::Body,
    extract::Path,
    http::{header, HeaderMap, HeaderValue, StatusCode},

HTTP range requests for video streaming in Axum

http-range-requests streaming async-io
Advanced 8 steps
ruby 
require "base64"
require "json"
 
module Attachment

Packing binary attachments into JSON

serialization base64 json
Intermediate 8 steps

Share this explainer

Here's the card — post it anywhere.

Trimming JSON output with serde attributes — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code