Ndtyjky

I got an issue while implement serializing/deserializing and sizing functionalities on a struct that have complex data types like Arc pointers Mutex locks. First I've resolved these Arc and Mutex serialization/deserialization problem using this topic:

How do I serialize or deserialize an Arc<T> in Serde?

but now, I got stuck on implementing ser/desr and sizing for Any and Send traits, and I have neither an idea nor a compiling example to solve this issue.

Code is here:

#[macro_use]

extern crate serde_derive;

extern crate serde;

extern crate serde_json;



use serde::Serialize;

use std::sync::Mutex;

use std::sync::Arc;

use std::any::Any;



#[derive(Debug, Clone, Serialize, Deserialize)]

pub struct Message {

    pub id: u64,

    pub data: Arc<Mutex<Any + Send>>,

}



#[derive(Debug, Clone, Serialize, Deserialize)]

pub struct Data {

    pub name: String,

}



impl Data {

    fn new(name_parameter: String) -> Data {

        let data = Data {

            name: name_parameter,

        };

        data

    }

}



fn main() {

    let msg: Message = Message { id: 23, data: (Arc::new(Mutex::new(Data::new(String::from("TesData"))))) };

    let ser_msg = serde_json::to_string(&msg).unwrap();

    let des_msg: Message = serde_json::from_str(&ser_msg).unwrap();



    println!("{:?}", msg);

    println!("{:?}", ser_msg);

    println!("{:?}", des_msg);

}

Here is the code in the Playground

It gives the following errors:

error[E0277]: the size for values of type `(dyn std::any::Any + std::marker::Send + 'static)` cannot be known at compilation time

  --> src/main.rs:15:5

   |

15 |     pub data: Arc<Mutex<Any + Send>>,

   |     ^^^ doesn't have a size known at compile-time

   |

   = help: the trait `std::marker::Sized` is not implemented for `(dyn std::any::Any + std::marker::Send + 'static)`

   = note: to learn more, visit <https://doc.rust-lang.org/book/second-edition/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait>

   = note: required because of the requirements on the impl of `serde::Serialize` for `std::sync::Mutex<(dyn std::any::Any + std::marker::Send + 'static)>`

   = note: required because of the requirements on the impl of `serde::Serialize` for `std::sync::Arc<std::sync::Mutex<(dyn std::any::Any + std::marker::Send + 'static)>>`

   = note: required by `serde::ser::SerializeStruct::serialize_field`



error[E0277]: the trait bound `(dyn std::any::Any + std::marker::Send + 'static): serde::Serialize` is not satisfied

  --> src/main.rs:15:5

   |

15 |     pub data: Arc<Mutex<Any + Send>>,

   |     ^^^ the trait `serde::Serialize` is not implemented for `(dyn std::any::Any + std::marker::Send + 'static)`

   |

   = note: required because of the requirements on the impl of `serde::Serialize` for `std::sync::Mutex<(dyn std::any::Any + std::marker::Send + 'static)>`

   = note: required because of the requirements on the impl of `serde::Serialize` for `std::sync::Arc<std::sync::Mutex<(dyn std::any::Any + std::marker::Send + 'static)>>`

   = note: required by `serde::ser::SerializeStruct::serialize_field`



error[E0277]: the trait bound `(dyn std::any::Any + std::marker::Send + 'static): serde::Deserialize<'_>` is not satisfied

  --> src/main.rs:15:5

   |

15 |     pub data: Arc<Mutex<Any + Send>>,

   |     ^^^ the trait `serde::Deserialize<'_>` is not implemented for `(dyn std::any::Any + std::marker::Send + 'static)`

You can use this solution as a work around but it should work it out for you i guess.

You have to access the data: Arc<Mutex<Any + Send>> then serialize/deserialze data and id separately.

#[macro_use]

extern crate serde_derive;

extern crate serde;

extern crate serde_json;



use serde::Serialize;

use std::sync::Mutex;

use std::sync::Arc;

use std::any::Any;



#[derive(Debug, Clone)]

pub struct Message {

    pub id: u64,

    pub data: Arc<Mutex<Any + Send>>,

}



#[derive(Debug, Clone, Serialize, Deserialize)]

pub struct Data {

    pub name: String,

}



impl Data {

    fn new(name_parameter: String) -> Data {

        let data = Data {

            name: name_parameter,

        };

        data

    }

}



fn main() {

    let msg: Message = Message { id: 23, data: (Arc::new(Mutex::new(Data::new(String::from("TesData"))))) };

    let _id = msg.id;

    let guard = msg.data.lock().unwrap();

    let msg_data: Option<&Data> = guard.downcast_ref::<Data>();

    let ser_msg_data = serde_json::to_string(&msg_data).unwrap();

    let des_msg_data: Data = serde_json::from_str(&ser_msg_data).unwrap();

    println!("{:?}", des_msg_data);

    let des_msg:Message = Message {id : _id, data: Arc::new(Mutex::new(des_msg_data))};

    println!("{:?}", msg);

    println!("{:?}", ser_msg_data);

    println!("{:?}", des_msg);



}

Here is the playground.
Playground