MyBatis 'IN' 子句中的列表 [英] Lists in MyBatis 'IN' clause
问题描述
如何将整数列表传递给 MyBatis XML,以便在 MySQL 查询的 in 子句中使用?
How can I pass an Integer List to MyBatis XML, to be used in an in clause in my MySQL query?
我在 mapper-xml
文件中使用 Java 7、MySQL 5.6 DB 和 MyBatis 3.0.4 进行查询.
I am using Java 7, MySQL 5.6 DB and MyBatis 3.0.4 with queries in a mapper-xml
file.
目前,我正在将此整数列表转换为字符串,并使用字符串替换(${}
运算符)将值放入IN"子句中 - 虽然它按预期工作,这种方法使参数容易受到注入攻击.
Presently, I am converting this list of integers to a string, and using string substitution (${}
operator) to put the values in the 'IN' clause - while it works as expected, this approach leaves the parameter vulnerable to Injection.
我曾尝试使用
元素,但我不知道要指定哪些属性.
I have tried using a <foreach>
element, but I am not able to figure out what attributes to specify.
下面是一个示例 Java 代码:
public List<Stripper> getStripperDetails(String club, List<Integer> stripperIds) {
Map<String, Object> input = new HashMap<>();
input.put("club", club);
input.put("stripperIds", stripperIds);
return stripClubMapper.getStripperDetails(input);
}
映射器 xml :
<select id="getStripperDetails" parameterType="java.util.HashMap" resultMap="StripperMap">
SELECT STRIPPER_ID, STAGE_NAME, REAL_NAME, CLUB FROM EXOTIC_DANCERS WHERE CLUB = #{club} AND STRIPPER_ID IN
<foreach item="item" index="index" collection="stripperIds" open="(" separator="," close=")">
#{index}
</foreach>
</select>
我无法弄清楚要为 <foreach>
元素指定哪些属性 - 对于 #{index} 处的值,我一直遇到 NullPointerException.
I am not able to figure out what attributes to specify for the <foreach>
element - I keep running into a NullPointerException for the value at #{index}.
你能帮我理解
元素的正确用法吗?
Can you please help me understand the correct usage of the <foreach>
element?
@10086 ,
下面是堆栈跟踪:
org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: java.lang.NullPointerException
### The error may involve com.stripclub.mapper.stripClubMapper.getStripperDetails-Inline
### The error occurred while setting parameters
### Cause: java.lang.NullPointerException
at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:67) ~[mybatis-spring-1.0.0-RC3.jar:1.0.0-RC3]
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:345) ~[mybatis-spring-1.0.0-RC3.jar:1.0.0-RC3]
at com.sun.proxy.$Proxy208.selectList(Unknown Source) ~[na:na]
at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:193) ~[mybatis-spring-1.0.0-RC3.jar:1.0.0-RC3]
at org.apache.ibatis.binding.MapperMethod.executeForList(MapperMethod.java:85) ~[mybatis-3.0.4.jar:3.0.4]
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:65) ~[mybatis-3.0.4.jar:3.0.4]
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:38) ~[mybatis-3.0.4.jar:3.0.4]
at com.sun.proxy.$Proxy209.getTransactionIds(Unknown Source) ~[na:na]
推荐答案
当与 Lists 一起使用时,应在 foreach 标签内使用 item 属性指定的值.如下使用:
The value specified by the item attribute should be used inside the foreach tag, when used with Lists. Use as below :
<foreach item="sId" collection="stripperIds" separator="," open="(" close=")">
#{sId}
</foreach>
索引属性不是强制性的,当使用列表时.有关更多信息,请参阅 MyBatis 文档部分,或查看 DTD - http://mybatis.org/dtd/mybatis-3-mapper.dtd 有关参数的更多信息:
The index attibute is not mandatory, when using a List. Refer the MyBatis docs section for more info, or check out the DTD - http://mybatis.org/dtd/mybatis-3-mapper.dtd for more info about the parameters :
<!ELEMENT foreach (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
<!ATTLIST foreach
collection CDATA #REQUIRED
item CDATA #IMPLIED
index CDATA #IMPLIED
open CDATA #IMPLIED
close CDATA #IMPLIED
separator CDATA #IMPLIED
>
此外,可以在 foreach 中访问对象列表,如下所示.您通常会将其用于 INSERT/UPDATE 语句:
Also, lists of objects can be accessed in foreach as below. You would typically use this for INSERT/UPDATE statements :
示例豆:
public class StripperBean {
public StripperBean(int stripperID, String stripperName, String realName) {
this.stripperID = stripperID;
this.stripperName = stripperName;
this.realName = realName;
}
private int stripperID;
private String stripperName;
private String realName;
public int getStripperID() {
return stripperID;
}
public void setStripperID(int stripperID) {
this.stripperID = stripperID;
}
public String getStripperName() {
return stripperName;
}
public void setStripperName(String stripperName) {
this.stripperName = stripperName;
}
public String getRealName() {
return realName;
}
public void setRealName(String realName) {
this.realName = realName;
}
}
在您的实施中:
Map<String, Object> input = new HashMap<>();
input.put("club", club);
List<StripperBean> strippers = new ArrayList<>();
strippers.add(new StripperBean(1,"Ashley", "Jean Grey"));
strippers.add(new StripperBean(2,"Candice","Diana Prince"));
strippers.add(new StripperBean(3,"Cristal","Lara Croft"));
input.put("strippers", strippers);
return stripClubMapper.saveStripperDetails(input);
在映射器 xml 中:
In the mapper xml :
<insert id="saveStripperDetails">
INSERT INTO EXOTIC_DANCERS (STRIPPER_ID, STAGE_NAME, REAL_NAME)
VALUES
<foreach item="stripper" collection="input" separator=",">
(#{stripper.stripperID},
#{stripper.stripperName},
#{stripper.realName})
</foreach>
</select>
好问题顺便说一句:)
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