What is the method to pass a collection in MyBatis?

2 years ago
Olivia Parker
2 minutes

There are two main ways to pass collections in Mybatis: using a List or a Map.

  1. Passing collections using List: When defining a method in the Mapper interface, you can directly pass a List as a parameter, and Mybatis will automatically pass the elements in the List as parameters to the SQL statement. For example:
public List<User> selectUserByIds(List<Integer> ids);

You can use the foreach tag in the XML configuration file to iterate through List parameters, as shown below:

<select id="selectUserByIds" resultType="User">
    SELECT * FROM user WHERE id IN
    <foreach item="item" index="index" collection="ids" open="(" separator="," close=")">
        #{item}
    </foreach>
</select>
  1. Passing collections using Map: Collections can be encapsulated as a Map and passed to SQL statements. When defining methods in the Mapper interface, you can pass in a Map as a parameter, where the key can be customized and the value is of collection type. For example:
public List<User> selectUserByIds(Map<String, Object> map);

In the XML configuration file, collection parameters can be accessed using the key of a Map, as shown below:

<select id="selectUserByIds" resultType="User">
    SELECT * FROM user WHERE id IN
    <foreach item="id" collection="ids" open="(" separator="," close=")">
        #{id}
    </foreach>
</select>

Both methods can effectively pass collection parameters to SQL statements, so choose the appropriate method based on the specific requirements in actual development.

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