映射自定义JdbcTemplate查询结果在一个对象中 [英] Map Custom JdbcTemplate query result in an Object

问题描述

我是Java新手，并尝试使用spring框架.我有个问题. 例如，我有桌子:

I new in java and try to use spring framework. I have a question. By example, I have table :

1. 员工(id_employee，姓名)
2. employee_product(id_employee_product，id_employee，product_name)

如果我从Employee表中选择一个雇员数据，则可以将其映射到POJO模型用户中，并在该模型中定义表结构，如下所示:

if I select an employee data from my Employee table, I can map it in a POJO model User and define the tables structure in that model, like this:

public class Employee {
    private final int id_employee;
    private final String nama;

    public Employee(int id_employee, String nama){
        this.id_employee = id_employee;
        this.nama = nama;
    }

    public int getId() {
        return id_employee;
    }

    public String getNama() {
        return nama;
    }
}

这是jdbcTemplate中的地图:

And this is the map from jdbcTemplate:

final String sql = "SELECT id_employee, nama FROM employee";
return jdbcTemplate.query(sql, (resultSet, i) -> {
    return new Employee(
            resultSet.getInt("id_employee"),
            resultSet.getString("nama")
    );
});

这是从1个表中选择数据的明显示例.

That is clear example for select data from 1 table.

我的问题是，如果我的数据是自定义查询，如何从查询映射数据?这样的我们使用联接并从该表中选择自定义字段，我是否需要为每个查询创建POJO?

My question is, how to map data from query if my data is custom query? Such us using join and select custom field from that tables, Am I need to create POJO every query?

有时候我只需要从我的员工表中选择employee.id_employee和employee.name字段即可.

Sometimes I need to select only employee.id_employee, and employee.name field from my employee table.

在另一个控制器中，我需要从我的employee表中选择employee.id_employee.

And in another controller I need to select employee.id_employee from my employee table.

在另一种情况下，我只需要选择employee.name和employee_product.product_name

In another case, I need only select employee.name, and employee_product.product_name

有没有一种方法可以映射数据而不为每种情况创建POJO?

Is there an alternative to map the data without creating POJO for every case?

推荐答案

创建一个结合了两个表的POJO

Create a one POJO combining two tables like this

public class Employee {
    private int id_employee;
    private String name;
    private int id_employee_product.
    private String product_name

    //getter and setters  
    //Don't create a constructor its Entiry
}

现在通过使用BeanPropertyRowMapper 文档链接将存储库写为

Now by using a BeanPropertyRowMapper Doc Link write your repository like

public List<Employee> fetchEmployeeProduct(){
    JdbcTemplate jdbcTemplate = new JdbcTemplate("Your_DataSource");
    StringBuilder query = new StringBuilder();
    query.append("Your Query");
    List<Employee> employeeProductList = 
        jdbcTemplate.query(query.toString(), new BeanPropertyRowMapper<Employee>(Employee.class));
}

确保查询中的SELECT子句与Employee POJO的文件名相同.

Make sure SELECT clause in the query and Employee POJO's filed name is same.

一旦执行查询，它将自动映射到POJO.您无需编写自定义映射器BeanPropertyRowMapper将负责映射.

Once if you execute your query it will automatically map to POJO. You no need to write a custom mapper BeanPropertyRowMapperwill take care of mapping.

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