Question 1

How to parse JSON from a file using serde_json?

Accepted Answer

Use serde_json::from_reader with a File object. For example, `let file = File::open('data.json')?; let data: MyStruct = serde_json::from_reader(file)?;`. This leverages the flexible I/O support for any io::Read source.

Question 2

Serde json vs simd json: which is better for performance?

Accepted Answer

Serde json offers excellent speed with type safety, but simd-json uses SIMD instructions for even higher raw parsing rates. Choose serde json for ecosystem integration and simd-json if you need every last bit of speed in dynamic scenarios.

Question 3

How to handle optional or missing fields in serde_json deserialization?

Accepted Answer

Use Option types in your structs, like `field: Option<String>`. Serde will deserialize missing fields to None. You can also use attributes like #[serde(default)] for custom fallbacks.

Question 4

Can serde_json parse JSON with comments or trailing commas?

Accepted Answer

No, serde_json strictly adheres to the JSON specification and does not support comments or trailing commas by default. You may need to preprocess the JSON or use a different library for lenient parsing.

Question 5

How to pretty print JSON output with serde_json?

Accepted Answer

Use serde_json::to_string_pretty instead of to_string for formatted output with indentation. This is useful for debugging or human-readable logs, though it may slightly impact performance.

Question 6

What's the difference between Value and typed structs in serde_json?

Accepted Answer

Value is an untyped enum for dynamic access, ideal for unknown schemas, but lacks compiler safety. Typed structs use Serde derives for compile-time validation and IDE support, making them safer for structured data.

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