quickwit-oss/quickwit · error · proc-macro compile error

structure implement deserialize but no deserializer defined

Error message

structure implement deserialize but no deserializer defined

What it means

In generate_proxy_struct, each field can declare a `try_from` (deserializer) conversion. If the struct implements Deserialize but a deserialized field has no `try_from` conversion defined, the macro cannot construct that field from the input and emits this error.

Source

Thrown at quickwit/quickwit-macros/src/lib.rs:200

                    return Err(Error::new(
                        field_name.span(),
                        "structure implement serialize but no serializer defined",
                    ));
                }
                (false, Some(_)) => {
                    return Err(Error::new(
                        field_name.span(),
                        "structure doesn't implement serialize but a serializer is defined",
                    ));
                }
            }
            match (de, field_config.get_try_from(&value)) {
                (true, Some(conv)) => {
                    try_from_conv.push(conv);
                }
                (false, None) => (),
                (true, None) => {
                    return Err(Error::new(
                        field_name.span(),
                        "structure implement deserialize but no deserializer defined",
                    ));
                }
                (false, Some(_)) => {
                    return Err(Error::new(
                        field_name.span(),
                        "structure doesn't implement deserialize but a deserializer is defined",
                    ));
                }
            }
        } else {
            pass_through.push(field_name);
            final_fields.push(field);
            if let Some(ponct) = ponct {
                final_fields.push_punct(ponct);
            }
        }

View on GitHub (pinned to a39730c5cd)

Solutions

1. Define the deserializer conversion for the field (e.g. `try_from = ...`) in the field's serde_multikey config.
2. Or exclude the field from the deserialization path if it should not be deserialized.

Example fix

// before
#[serde_multikey(
    fields(value)
)]
// after
#[serde_multikey(
    fields(value(try_from = parse_value))
)]

// For every field in fields(...) of a Deserialize struct, ensure a `try_from` conversion exists:
// #[serde_multikey(fields(value(try_from = parse_value)))]

When it happens

Trigger: The struct has a Deserialize impl/derive, and a field in the deserialization path lacks the required `try_from = ...` conversion in its serde_multikey field config.

Common situations: Adding a new field to a deserialized multikey struct without adding its `try_from` conversion; removing a conversion during refactoring.

Understand the failure class

Background: "Must pass :limit option" / "Missing required option" — required option errors explained — this error's family across 41 libraries.

Related errors

• `serde_multikey` was applied to a non Serialize/Deserialize
• `serde_multikey` was applied to a tuple-struct or an empty s
• structure implement serialize but no serializer defined
• structure doesn't implement serialize but a serializer is de
• structure doesn't implement deserialize but a deserializer i

AI-assisted analysis of quickwit-oss/quickwit@a39730c5cd (2026-09-08). Data as JSON: /api/errors/1416a5b49fdf595e. Report an issue: GitHub.