JSON to Rust struct generator

How to use it

1. Paste a JSON sample. Arrays with several objects give the best result.
2. Choose whether structs and fields are pub and whether None values are skipped when serializing.
3. Copy the code into your crate and parse with let root: Root = serde_json::from_str(&text)?;.

How it works

The sample is read into a shape: every key with every type seen at that place. All objects of one array are merged into one struct, so a key present in only some of them becomes Option.

• Each struct derives Debug, Clone, Serialize and Deserialize.
• Struct names come from keys: items holds Vec, customer becomes Customer.
• A top-level array gives a type alias, such as pub type Root = Vec;.

Worked example

{"items":[{"sku":"A","note":null,"qty":1},{"sku":"B","note":"x"}]} without pub and with Skip None gives:

use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize)]
struct Root {
    items: Vec<Item>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct Item {
    sku: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    note: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    qty: Option<i64>,
}

Tips

• If every key is camelCase, you can replace the per-field renames with one #[serde(rename_all = “camelCase”)] on the struct.
• Narrow types where you know the range: u32 for counts, u8 for small codes.
• Add #[serde(deny_unknown_fields)] if extra keys should be an error.