A nested struct deserializer problem

[wjwei-handsome]

A nested struct deserializer problem

[BurntSushi]

I spent about 10 minutes looking into this, and I can't make heads or tails of it myself. I note, for example, that this works:

#[derive(Serialize, Debug, Deserialize)]
struct Foo {
    a: String,
    b: String,
    c: String,
    d: String,
}

So to me, the serde(flatten) example you have should also work since it should be equivalent to the above.

If you look at the issues on this tracker, a lot of them are about Serde. And of those issues, a lot of thoses are about serde(flatten). It is really one of the worst things about maintaining this library.

[BurntSushi]

I also note that this works:

use serde::{Serialize, Deserialize};

#[derive(Serialize, Debug, Deserialize)]
struct Foo {
    #[serde(flatten)]
    bar1: Bar,
    #[serde(flatten)]
    bar2: Bar2,
}

#[derive(Serialize, Debug, Deserialize)]
struct Bar {
    a: String,
    b: String,
}

#[derive(Serialize, Debug, Deserialize)]
struct Bar2 {
    c: String,
    d: String,
}

fn main() {
    let csv_ = "a,b,c,d\nw,x,y,z\nq,w,e,r\n";
    let f :Foo = csv::ReaderBuilder::new()
        .from_reader(csv_.as_bytes())
	    .deserialize().next().unwrap().unwrap();
	println!("{:?}", f)
}

So there is likely something funny going on with the support for Serde without header names. Since you're duplicating a struct here, I suspect what you want to do is either not possible or requires work on the Serde deserializer in this crate to make it work. (And I'm not even sure the latter is possible.)

[wjwei-handsome]

Thank you very much for your attention.

I also think the error comes from serde,

I fully understand and I will try your suggestion.

Best wishes!