---
name: serde-serialization-93cad8f3496d
description: Rust serialization/deserialization framework for JSON, YAML, TOML, and more.
metadata:
  labels: [rust, serde, serialization, json]
  triggers:
    files: ['**/*.rs']
    keywords: [Serialize, Deserialize, serde, serde_json]
---

# Serde Standards

## Basic Usage

```rust
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, Debug)]
struct User {
    id: u64,
    name: String,
    email: String,
    #[serde(default)]
    active: bool,
}

// Serialize to JSON
let user = User { id: 1, name: "Alice".into(), email: "a@b.com".into(), active: true };
let json = serde_json::to_string(&user)?;

// Deserialize from JSON
let user: User = serde_json::from_str(&json)?;
```

## Field Attributes

```rust
#[derive(Serialize, Deserialize)]
struct Config {
    // Rename field in JSON
    #[serde(rename = "apiKey")]
    api_key: String,

    // Skip serializing if None
    #[serde(skip_serializing_if = "Option::is_none")]
    description: Option<String>,

    // Default value if missing
    #[serde(default = "default_timeout")]
    timeout_secs: u64,

    // Skip entirely
    #[serde(skip)]
    internal_state: bool,

    // Flatten nested struct
    #[serde(flatten)]
    metadata: Metadata,
}

fn default_timeout() -> u64 { 30 }
```

## Enums

```rust
#[derive(Serialize, Deserialize)]
#[serde(tag = "type")]  // Tagged union
enum Event {
    #[serde(rename = "user_created")]
    UserCreated { id: u64, email: String },

    #[serde(rename = "user_deleted")]
    UserDeleted { id: u64 },
}

// Serializes as: {"type": "user_created", "id": 1, "email": "..."}

// Untagged variant
#[derive(Serialize, Deserialize)]
#[serde(untagged)]
enum Value {
    Integer(i64),
    Float(f64),
    String(String),
}
```

## Custom Serialization

```rust
use serde::{Serializer, Deserializer};

#[derive(Serialize, Deserialize)]
struct Record {
    #[serde(serialize_with = "serialize_datetime")]
    #[serde(deserialize_with = "deserialize_datetime")]
    created_at: DateTime<Utc>,
}

fn serialize_datetime<S>(dt: &DateTime<Utc>, s: S) -> Result<S::Ok, S::Error>
where S: Serializer {
    s.serialize_str(&dt.to_rfc3339())
}

fn deserialize_datetime<'de, D>(d: D) -> Result<DateTime<Utc>, D::Error>
where D: Deserializer<'de> {
    let s = String::deserialize(d)?;
    DateTime::parse_from_rfc3339(&s)
        .map(|dt| dt.with_timezone(&Utc))
        .map_err(serde::de::Error::custom)
}
```

## Format Support

| Format | Crate | Use Case |
|--------|-------|----------|
| JSON | `serde_json` | APIs, config |
| YAML | `serde_yaml` | Config files |
| TOML | `toml` | Cargo.toml style |
| MessagePack | `rmp-serde` | Binary, compact |
| CBOR | `ciborium` | Binary, standards |

## Validation with Derive

```rust
use serde::Deserialize;
use validator::Validate;

#[derive(Deserialize, Validate)]
struct CreateUser {
    #[validate(length(min = 1, max = 100))]
    name: String,

    #[validate(email)]
    email: String,

    #[validate(range(min = 18, max = 120))]
    age: u8,
}
```

## Best Practices

1. **Deny unknown fields**: `#[serde(deny_unknown_fields)]` for strict parsing
2. **Rename all**: `#[serde(rename_all = "camelCase")]` for consistent naming
3. **Default trait**: Implement `Default` for optional defaults
4. **Error context**: Use `anyhow` or custom errors for better messages
5. **Performance**: Use `serde_json::from_slice` for bytes, avoid string conversion


---
Source attribution: ngxtm
Original project: https://github.com/ngxtm/devkit/blob/9439f27ce3fa7fe53ff9278a1ee9a44bffa70eba/rules/rust/serde-serialization/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2024

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: ngxtm
Original project: https://github.com/ngxtm/devkit/blob/9439f27ce3fa7fe53ff9278a1ee9a44bffa70eba/rules/rust/serde-serialization/SKILL.md
Attribution basis: Source repository record

Fields of work: Development & Engineering
Roles: Backend Developer, Data Engineer
Specialties: API, Backend
Tools: Rust, Serde
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 4fc2554e8b12c1a324af47334c5a0fc00ca908d90a25081a697eef11b04f7d11