Escaping character with serde deserialization
Published on Mar 17, 2024 by math-almeida.

Supose you have a struct with the following data model:

#[derive(Debug, serde::Deserialize)]
struct Form<'a> {
    password: &'a str,
}

If you input a value using this model with an escape character this error will happend:

Err(Error("invalid type: string \"123\\\"456\", expected a borrowed string", line: 1, column: 24))

Why this happend? If we think in the impl we come to the following question: How is serde supposed to do zero-copy deserialization. which is implied by &str, with an escape character?

You can change this reference to Cow¹ wich means clone-on-write who can enclose and provide immutable access to borrowed data.

#[derive(Debug, serde::Deserialize)]
struct Form<'a> {
    password: std::borrow::Cow<'a, str>,
}

Here is a playground that demonstrate the issue.