How do you handle missing or optional fields in serde_json?

Handle optional JSON fields in Rust using Option<T> types in your struct: field: Option<String> allows null or missing fields. Serde automatically treats Option fields as optional—missing fields deserialize to None. Use #[serde(default)] on the struct or specific fields to use Default trait values when fields are missing. For custom defaults, use #[serde(default = "default_function")] where default_function returns the desired value. The #[serde(skip_serializing_if = "Option::is_none")] attribute omits None values during serialization. Distinguish between null and missing with #[serde(skip_serializing_if = "Option::is_none", default)]. Required fields without Option cause deserialization to fail with clear error messages if missing. This strict behavior catches data quality issues early. Validate JSON structure with our JSON Editor at jsonconsole.com/json-editor to identify which fields are consistently present. Option<T> is the idiomatic Rust approach to nullable/optional data. Proper optional field handling makes your Rust code robust against varying JSON inputs.