Mybatis实体类对象入参查询的笔记

2022-11-13 10:11:16 查询对象笔记

Mybatis实体类对象入参查询

测试实体类对象结构如下


@Getter
@Setter
@NoArgsConstructor
@ToString
@EqualsAndHashCode
public class Vendor {
    private String vend_id;
    private String vend_name;
    private String vend_address;
    private String vend_city;
    private String vend_state;
    private String vend_zip;
    private String vend_country;
}

XML映射文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "Http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.mapper.VendORMapper">  
  <select id="findByVendorEntity" parameterType="vendor" resultType="vendor">
      select * from Vendors where vend_id = #{vend_id} and vend_name = #{vend_name}
  </select>
</mapper>

接口文件

public interface VendorMapper {
    //通过Vendor对象查询
    Vendors findByVendorEntity(Vendor vendor);
}

测试文件内容

try {
            String resource = "mybatis-config.xml";
            InputStream resourceAsStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory build = new SqlSessionFactoryBuilder().build(resourceAsStream,"development2");
            //获取SQLSession
            SqlSession openSession = build.openSession();
            
            VendorMapper mapper = openSession.getMapper(VendorMapper.class);
            Vendor vendor = new Vendor();
            vendor.setId("BRE02");
            vendor.setName("Bear Emporium");
            
            Vendor findByVendorEntity = mapper.findByVendorEntity(vendor);
            System.out.println(findByVendorEntity);
        } catch (IOException e) {
            System.out.println("加载配置文件失败");
            e.printStackTrace();
        }

笔记：

当对象作为参数传入查询时(不一定指定parameterType属性值为实体对象的别名或全路径名,typeHandler貌似会自动识别),SQL查询语句的#{}中内容需要与实体类的字段属性一一对应(并非实体类的属性一定是数据库表中的字段,只要填入的值对应即可。

mybatis查询条件是看sql语句的where后的查询条件)，如果表达式中的值没有对应，则会报错。

错误示例如下：

....Cause:org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ids' in 'class com.mybatis.beans.Vendors' ....Cause:org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ids' in 'class com.mybatis.beans.Vendors'...