If you want to keep a certain part of your data deserialized but you don't know the structure of the data and you want to explore it later in runtime, you can use the generic serde_json::Value, which represents a value of any type. For example, the serde_json crate includes a Value object and a method to deserialize types from an instance of Value. This may be useful in difficult deserialization cases in which you need to reorder the representation before it's completely deserialized.

To use a generic Value, add it to your struct. Consider the following, for example:

#[derive(Deserialize)]
struct Response {
    id: u32,
    result: serde_json::Value,
}

Here, we used a generic value of the serde_json crate. When you need to deserialize it to a User struct, for example, you can use the serde_json::from_value function:

let u: User = serde_json::from_value(&response)?;

In this section, we learned about deserialization processes. It's now time to add a handler to our server to process requests. This handler will deserialize the data, generate a random value, and return the data back in its serialized form to the client.