Transfer Object (DTO) using WebClient and Mono, extra fields in the JSON will typically be disregarded

Yes, generally, when you're mapping the JSON responses from your web services into a Data Transfer Object (DTO) using WebClient and Mono, extra fields in the JSON will typically be disregarded if they don't have corresponding fields in your DTO. Here's a breakdown of how it works and some important considerations:

How JSON Mapping Works:

• Object Mapping:

  • Libraries like Jackson (which is often used by default in Spring WebFlux) are responsible for converting the JSON data into Java objects (your DTOs).

  • During this process, the mapper attempts to match JSON field names to the corresponding fields in your DTO class.

• Ignoring Extra Fields:

  • By default, if the JSON contains fields that don't exist in your DTO, Jackson will usually ignore them. This is a common and often desired behavior.

  • This helps maintain compatibility when APIs evolve and add new fields, as your existing DTOs won't break.

Important Considerations:

• Jackson Configuration:

  • While the default behavior is to ignore extra fields, Jackson's behavior can be customized.

  • You can configure Jackson to throw an exception if it encounters unknown fields, which can be useful for strict validation.

  • Annotations like @JsonIgnoreProperties(ignoreUnknown = true) can also be used on your DTO classes to explicitly control how unknown fields are handled.

• DTO Design:

  • It's generally a good practice to design your DTOs to contain only the fields that your application actually needs.

  • This helps reduce the amount of data that needs to be processed and improves the clarity of your code.

• API Versioning:

  • If your APIs are subject to frequent changes, consider implementing API versioning.

  • This allows you to maintain compatibility with older clients while introducing new features and fields in newer versions.

In summary:

• When using WebClient and Mono to map JSON responses to DTOs, extra fields in the JSON will typically be ignored.

• You can control this behavior through Jackson configuration and by carefully designing your DTOs.

I hope this helps!