服务获取一个包含三个值列表的未知对象[column,operator,value]例如, EMAIL - 就像 - “TEST”
根据结果列表构建我有的WHERE子句但我也能够构建如下的条件(例如)
WHERE(电子邮件,例如'test'和user_id<> 5)或(trans_id< 100 AND session_id> 500)
有没有人可以帮我怎么做?
答案 0 :(得分:8)
我自己长期缺席后一直在重新发现MyBatis(我一度熟悉iBatis)。 Rolf的例子看起来可能是.Net实现,我可能错了,但我认为Java符号现在看起来不像。罗尔夫关于文字字符串的提示非常有用。
我创建了一个小类来保存你的列,运算符和值,并将它们传递给MyBatis来进行处理。列和运算符是字符串文字,但我将值保留为sql参数(我想MyBatis可以进行任何必要的类型转换)。
public class TestAnswer {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
SqlSessionFactory sqlFactory = (SqlSessionFactory) ctx.getBean("sqlSessionFactory");
MappedStatement statement = sqlFactory.getConfiguration().getMappedStatement("testAnswer");
ArrayList<Clause> params1 = new ArrayList<Clause>();
params1.add(new Clause("email","like","test"));
params1.add(new Clause("user","<>",5));
ArrayList<Clause> params2 = new ArrayList<Clause>();
params2.add(new Clause("trans_id","<",100));
params2.add(new Clause("session_id",">",500));
HashMap params = new HashMap();
params.put("params1", params1);
params.put("params2", params2);
BoundSql boundSql = statement.getBoundSql(params);
System.out.println(boundSql.getSql());
}
static class Clause{
private String column;
private String operator;
private Object value;
public Clause(String column, String operator, Object value){
this.column = column;
this.operator = operator;
this.value = value;
}
public void setColumn(String column) {this.column = column;}
public void setOperator(String operator) {this.operator = operator;}
public void setValue(Object value) {this.value = value;}
public String getColumn() {return column;}
public String getOperator() {return operator;}
public Object getValue() {return value;}
}
}
正如您所看到的,我使用Spring但我希望类似的东西可能在Spring环境之外工作。
<?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.stackoverflow.TestMapper">
<select id="testAnswer" parameterType="map" resultType="hashmap">
select *
FROM somewhere
<where>
<foreach item="clause" collection="params1" separator=" AND " open="(" close=")">
${clause.column} ${clause.operator} #{clause.value}
</foreach>
OR
<foreach item="clause" collection="params2" separator=" AND " open="(" close=")">
${clause.column} ${clause.operator} #{clause.value}
</foreach>
</where>
</select>
</mapper>
答案 1 :(得分:1)
这个答案有两个关键部分。一个是“动态”元素,另一个是你问题中“运算符”周围的$$文字元素。
<select id="yourSelect" parameterClass="Map" resultMap="somethingsomething" >
select * from YOURTABLE
<dynamic prepend="WHERE">
<isNotNull prepend="AND" property="email">
email $operator$ #testvalue#
</isNotNull>
</dynamic>
</select>
另请参阅有关此主题的DataMapper Dynamic SQL documentation。