Deserializing boxed trait without knowing what type it is about erased-serde HOT 4 CLOSED

You would need to provide an implementation of Deserialize for your trait object:

use serde::{Deserialize, Deserializer};

trait Foo: erased_serde::Serialize + Debug {}
serialize_trait_object!(Foo);

impl<'de> Deserialize<'de> for Box<dyn Foo> {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        /* your implementation here */
    }
}

The Deserialize impl can use whatever means makes sense to determine which concrete Foo implementation(s) to produce.

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The serialized json string is [null,null,null] so the type information is already lost. Do you know how to get the type name into the serialized version? Will that require manually impl serialize?

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@dtolnay I also would like to deserialize with an erased type. In my case, I already have an object in memory of the correct type, behind a trait object, and I would like to invoke deserialize_in_place on it, using some type erasure magic to make it work through the trait object. Is that possible? Any hint on how to implement it?

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I think @CasperN's use case is addressed by https://github.com/dtolnay/typetag and @rasky's by #33.

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