@Id
@Id is an annotation that identifies a property or field as the persistent identity of an entity or object.
Spring in Action, Sixth Edition
@Id is a Spring Data JDBC annotation that marks a domain-property field as the persistent identity of an object.
- How it is used
- Marks the property that identifies a persisted domain object, row, or document.
- How deep it goes
- Explains placement, supported identifier examples, and namespace differences, but does not detail identifier-generation internals.
- Examples
- Uses TacoOrder, Taco, Ingredient, and IngredientRef classes with Long or String identity properties.
- What you can do after
- Apply the correct @Id variant to identity properties in Spring Data JDBC, JPA, or MongoDB domain types.
Java Persistence with Spring Data and Hibernate epub
@Id is the JPA annotation that marks a persistent property or field as an entity identifier.
- How it is used
- Marks the property that exposes database identity for JPA entities and Spring Data JDBC aggregates.
- How deep it goes
- Explains required identifiers, default ID mapping, field access, generated values, and explicit column mapping without covering composite identifiers.
- Examples
- Uses generated Long ids on Item and an explicitly mapped ID field on a Spring Data JDBC User.
- What you can do after
- Apply it via JPA or Spring Data JDBC to map entity identity and support identifier-based persistence and lookup.
Read how Java Persistence with Spring Data and Hibernate epub explains @Id →
Related concepts
- unique identifierconfigures · A unique identifier is a value or name that distinguishes an entity or record from others within a defined scope or namespace.
- entityconfigures · An entity is a distinct, identifiable person, object, event, or concept represented as a unit in a data, software, or semantic model.
- Spring Data JDBCused by · Spring Data JDBC is a Spring Data module that provides repository-based access to relational databases through JDBC without requiring a full object-relational mapping framework.
- Hibernateconfigures · Hibernate is a Java object-relational mapping and persistence framework that maps application objects to relational database data.
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