我可以将列表作为参数传递给MyBatis映射器吗?

问题描述

我正在尝试在MyBatis中定义一个简单的@Select批注，以基于由IN子句定义的条件来获取对象的集合. SQL看起来像:

I'm trying to define a simple @Select annotation in MyBatis to get a collection of objects based on criteria defined by an IN clause. The SQL looks something like:

SELECT * FROM employees WHERE employeeID IN (1, 2, 3);

该列表是动态生成的，因此我不知道它将具有多少个参数.我只想传递List值，例如:

The list is generated dynamically, so I don't know how many parameters it will have. I'd like to just pass in a List of values, something like:

@Select("SELECT * FROM employees WHERE employeeID IN( #{employeeIds} )")
List<Employee> selectSpecificEmployees(@Param("employeeIds") List<Integer> employeeIds);

我正在创建Mapper的实例，在其中定义了上面的注释，并按如下方式调用它:

I'm creating an instance of the Mapper where the annotation above is defined and calling it as follows:

List<Integer> empIds = Arrays.asList(1, 2, 3);
List<Employee> result = mapper.selectSpecificEmployees(empIds);

我发现这行不通.

我认为问题出在注释本身.这似乎是一个相当普遍的要求.我是否需要自己将List转换为String并将其作为String参数而不是List<Integer>传递?还是有其他语法可以将List作为参数传递给MyBatis批注?

I think the problem is in the annotation itself. This seems like it would be a fairly common requirement. Do I need to convert the List to a String myself and pass that in as a String parameter instead of a List<Integer>? Or is there some other syntax for passing a List as a parameter to a MyBatis annotation?

推荐答案

我以前从未使用过注解和MyBatis.我一直走过xml配置文件路由(不是暗示使用批注有什么问题；只是在解释我不能为您提供帮助).

I've never used annotations and MyBatis before; I've always gone the xml configuration file route (not implying there is anything wrong with using annotations; just explaining I can't help you there).

话虽如此，《 MyBatis用户指南》中的第46页:

That being said, page 46 from the MyBatis user guide:

动态SQL的另一个常见需求是需要迭代一个 收集时，通常会建立一个IN条件.例如:

Another common necessity for dynamic SQL is the need to iterate over a collection, often to build an IN condition. For example:

<select id="selectPostIn" resultType="domain.blog.Post">
    SELECT *
    FROM POST P
    WHERE ID in
    <foreach item="item" index="index" collection="list"
        open="(" separator="," close=")">
          #{item}
    </foreach>
  </select>

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