Flattening & Unflattening

Flattening

Flattening converts nested JSON into a flat key-value structure using dot-separated (or custom) keys.

// Input
{"user": {"name": "John", "address": {"city": "NYC", "zip": "10001"}}}

// Output (flattened)
{"user.name": "John", "user.address.city": "NYC", "user.address.zip": "10001"}

Arrays

Arrays are flattened with numeric indices:

// Input
{"users": [{"name": "Alice"}, {"name": "Bob"}]}

// Output
{"users.0.name": "Alice", "users.1.name": "Bob"}

Custom Separators

Use .separator() to change the key delimiter:

#![allow(unused)]
fn main() {
let result = JSONTools::new()
    .flatten()
    .separator("::")
    .execute(json)?;
// {"user::name": "John", "user::address::city": "NYC"}
}

result = jt.JSONTools().flatten().separator("::").execute(data)

Unflattening

Unflattening reverses the process, reconstructing nested structures from flat keys.

// Input
{"user.name": "John", "user.address.city": "NYC"}

// Output (unflattened)
{"user": {"name": "John", "address": {"city": "NYC"}}}

Numeric keys reconstruct arrays:

// Input
{"users.0.name": "Alice", "users.1.name": "Bob"}

// Output
{"users": [{"name": "Alice"}, {"name": "Bob"}]}

Roundtrip

Flattening and unflattening are perfect inverses. You can flatten data, apply transformations, then unflatten to recover the original structure:

#![allow(unused)]
fn main() {
let original = r#"{"user": {"name": "John", "scores": [10, 20, 30]}}"#;

// Flatten
let flat = JSONTools::new().flatten().execute(original)?;

// Unflatten back
let restored = JSONTools::new().unflatten().execute(
    &flat.into_single()
)?;
// Matches original structure
}