https://github.com/vivek-dhamanemath/hibernate-criteria-builder
https://github.com/vivek-dhamanemath/hibernate-criteria-builder
criteriabuilder hibernate
Last synced: 3 months ago
JSON representation
- Host: GitHub
- URL: https://github.com/vivek-dhamanemath/hibernate-criteria-builder
- Owner: vivek-dhamanemath
- Created: 2025-01-09T17:23:10.000Z (6 months ago)
- Default Branch: master
- Last Pushed: 2025-01-09T17:32:29.000Z (6 months ago)
- Last Synced: 2025-01-29T16:14:11.128Z (5 months ago)
- Topics: criteriabuilder, hibernate
- Language: Java
- Homepage:
- Size: 12.7 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Hibernate CriteriaBuilder
## Overview
This project demonstrates the use of the `CriteriaBuilder` interface in Hibernate, which is part of the `javax.persistence.criteria` package. The `CriteriaBuilder` was introduced to overcome the drawbacks of the Criteria API. It allows us to create different types of criteria to perform specific operations without hardcoding queries as strings.
## Key Components
### CriteriaBuilder
- **Purpose**: Acts as a builder to generate objects for different types of criteria.
- **Usage**: Create an instance using the `getCriteriaBuilder()` method from the session object.
- **Functionality**: Helps construct queries using inbuilt methods, but does not execute them.
### Criteria Types
1. **CriteriaQuery**
- **Purpose**: Used for data retrieval from the database.
- **Creation**: Use `createQuery()` method from `CriteriaBuilder`.
- **Methods**:
- `from()`: Fetches all records from the respective table and stores them in a root element.
- **Execution**: Use the `Query` interface to execute the constructed query.
```java
// Example of CriteriaQuery
Session session = sessionFactory.openSession();
CriteriaBuilder cb = session.getCriteriaBuilder();
CriteriaQuery cq = cb.createQuery(Employee.class);
Root root = cq.from(Employee.class);
cq.select(root);
Query query = session.createQuery(cq);
List employees = query.getResultList();
```
2. **CriteriaUpdate**
- **Purpose**: Used for updating data in the database.
- **Creation**: Use `createCriteriaUpdate()` method from `CriteriaBuilder`.
- **Methods**:
- `from()`: Fetches all records from the respective table and stores them in a root element.
- `set()`: Sets the values for columns to be updated.
- **Execution**: Use the `Query` interface to execute the constructed query using `executeUpdate()` method.
```java
// Example of CriteriaUpdate
Session session = sessionFactory.openSession();
CriteriaBuilder cb = session.getCriteriaBuilder();
CriteriaUpdate cu = cb.createCriteriaUpdate(Employee.class);
Root root = cu.from(Employee.class);
cu.set("salary", 50000);
cu.where(cb.equal(root.get("id"), 1));
Query query = session.createQuery(cu);
int rowsUpdated = query.executeUpdate();
```
3. **CriteriaDelete**
- **Purpose**: Used for deleting data from the database.
- **Creation**: Use `createCriteriaDelete()` method from `CriteriaBuilder`.
- **Methods**:
- `from()`: Fetches all records from the respective table and stores them in a root element.
- **Execution**: Use the `Query` interface to execute the constructed query using `executeUpdate()` method.
```java
// Example of CriteriaDelete
Session session = sessionFactory.openSession();
CriteriaBuilder cb = session.getCriteriaBuilder();
CriteriaDelete cd = cb.createCriteriaDelete(Employee.class);
Root root = cd.from(Employee.class);
cd.where(cb.equal(root.get("id"), 1));
Query query = session.createQuery(cd);
int rowsDeleted = query.executeUpdate();
```
## Notes
### CriteriaBuilder
- It is an interface present in `javax.persistence.criteria` package.
- It was introduced to overcome the drawbacks of Criteria API.
- Using `CriteriaBuilder` we can create different types of criteria to perform specific operations.
- `CriteriaBuilder` acts as a builder responsible for generating objects for different types of criteria.
- We can create an object of `CriteriaBuilder` by invoking the `getCriteriaBuilder()` method using the session object.
- Using `CriteriaBuilder`, we don't need to hardcode the query as a string; instead, we use inbuilt methods to construct the query.
- It is only used to construct the query and not responsible for executing it.
- To execute the query, we need to create an instance of the `Query` interface.
### CriteriaQuery
- It is an interface present in `javax.persistence.criteria` package.
- It is used specifically for data retrieval from the database.
- We can create an object of `CriteriaQuery` by invoking the `createQuery()` method using the `CriteriaBuilder` object.
- The `createQuery()` method accepts the entity class name as the parameter to construct the query.
- It has a method called `from()` which accepts the entity class name as the parameter to fetch all records from the respective table and store them inside a root element.
- The user is provided with several methods to represent the `where` clause and various other expressions needed for the query.
- To execute the query after it is constructed, we need to use the `Query` interface.
### CriteriaUpdate
- It is an interface present in `javax.persistence.criteria` package.
- It is used specifically for updating data in the database.
- We can create an object of `CriteriaUpdate` by invoking the `createCriteriaUpdate()` method using the `CriteriaBuilder` object.
- The `createCriteriaUpdate()` method accepts the entity class name as the parameter to construct the query.
- It has a method called `from()` which accepts the entity class name as the parameter to fetch all records from the respective table and store them inside a root element.
- We use the `set` method from `CriteriaUpdate` to set the values for columns to be updated.
- The user is provided with several methods to represent the `where` clause and various other expressions needed for the query.
- To execute the query after it is constructed, we need to use the `Query` interface and the `executeUpdate()` method.
### CriteriaDelete
- It is an interface present in `javax.persistence.criteria` package.
- It is used specifically for deleting data from the database.
- We can create an object of `CriteriaDelete` by invoking the `createCriteriaDelete()` method using the `CriteriaBuilder` object.
- The `createCriteriaDelete()` method accepts the entity class name as the parameter to construct the query.
- It has a method called `from()` which accepts the entity class name as the parameter to fetch all records from the respective table and store them inside a root element.
- The user is provided with several methods to represent the `where` clause and various other expressions needed for the query.
- To execute the query after it is constructed, we need to use the `Query` interface and the `executeUpdate()` method.