How can I deserialize JSON with a top-level array using Serde?

You can simply use a Vec:

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, Debug)]
struct Foo {
    data: String,
}

fn main() -> Result<(), serde_json::Error> {
    let data = r#"[
        {
            "data": "value1"
        },
        {
            "data": "value2"
        },
        {
            "data": "value3"
        }
    ]"#;

    let datas: Vec<Foo> = serde_json::from_str(data)?;

    for data in datas.iter() {
        println!("{:#?}", data);
    }

    Ok(())
}

---

If you wish, you could also use transparent:

#[derive(Serialize, Deserialize, Debug)]
#[serde(transparent)]
struct Foos {
    foos: Vec<Foo>,
}

let foos: Foos = serde_json::from_str(data)?;

This allows to encapsulate your data with your type.