How can I accept multiple deserialization names for the same Serde field?

Question

I am trying to use Serde to deserialize JSON (serde-json) and XML (serde-xml-rs) files based on the following struct:

use serde_derive::Deserialize; #[derive(Debug, Clone, PartialEq, Deserialize)] pub struct SchemaConfig { pub name: String, #[serde(rename = "Cube")] pub cubes: Vec<CubeConfig>, }

The fields I am deserializing on have different names based on the file type. In this case, I would like for a JSON file to have a cubes key with a list of cubes, but the equivalent in XML would be multiple <Cube /> elements.

I can't figure out how to accept both cubes and Cube as keys for the deserialization. The closest thing I found was the #[serde(rename = "Cube")] option but when I use that the JSON deserialization stops working since it only accepts the Cube key. If I remove that option, the XML deserialization stops working as it then only accepts cubes as the key.

Is there a simple way to accomplish this in Serde?

Shepmaster · Accepted Answer · 2019-03-30 13:38:37Z

I encourage you to read the Serde documentation. The field attributes chapter introduces the alias attribute, emphasis mine:

#[serde(alias = "name")]

Deserialize this field from the given name or from its Rust name. May be repeated to specify multiple possible names for the same field.

use serde::Deserialize; // 1.0.88 use serde_json; // 1.0.38 #[derive(Debug, Deserialize)] struct SchemaConfig { #[serde(alias = "fancy_square", alias = "KUBE")] cube: [i32; 3], } fn main() -> Result<(), Box<std::error::Error>> { let input1 = r#"{ "fancy_square": [1, 2, 3] }"#; let input2 = r#"{ "KUBE": [4, 5, 6] }"#; let one: SchemaConfig = serde_json::from_str(input1)?; let two: SchemaConfig = serde_json::from_str(input2)?; println!("{:?}", one); println!("{:?}", two); Ok(()) }

I would like for a JSON file to have a cubes key with a list of cubes, but the equivalent in XML would be multiple <Cube /> elements.

This certainly sounds like you want two different structures to your files. In that case, look at something like:

Thank you for the code sample. I did read the documentation, but it wasn't clear to me from the documentation how to specify multiple alias values. Your code sample here makes it perfectly clear. 👍
This looks the only workaround. but it's buggy. think about fancy_square and KUBE can be in the same file or different file.

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