JSON

Understand the idea

Objects contain named values; arrays contain ordered values. Strings require double quotes. true and false are booleans, not quoted strings. Spring’s message converters map JSON into DTOs and serialize response objects.

A concrete example

{"title":"Learn Spring","completed":false}

In the application

Postman raw JSON and React JSON.stringify produce the request bodies accepted by the API controllers.

JSON syntax, DTO field types, and validation constraints are separate checks. A syntactically valid body can still fail validation.

Related concepts

• DTO · Data Transfer Object
• Request-body binding
• REST / resource API