Mybatis parameterType

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. Primary data type

  • mapper interface

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    User selectByPrimaryKey(Integer id);

  • sql mapping

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    <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
      select
      <include refid="Base_Column_List" />
      from user
      where id = #{id,jdbcType=INTEGER}
    </select>

The id in this condition can be any name, it all represent the Integer parameter.

Discuss

if Integer argument need be judge use _parameter represent it in tag <if>

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<select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
  select
  <include refid="Base_Column_List" />
  from tb_user
  <if test="_parameter != 0">
  where id = #{id,jdbcType=INTEGER}
  </if>
</select>

Object data type

  • mapper interface

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    int insert(User user);

  • sql mapping

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    <insert id="insert" parameterType="User" useGeneratedKeys="true" keyProperty="id">
      insert into tb_user (name)
      values (#{name,jdbcType=CHAR})

  • The name in value must be the User object’s property name

  • If <if> tag want to judge whether user is null, _parameter variable need be used. like above discuss content.

Map data type

  • mapper interface

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    int updateByExample(@Param("user") User user, @Param("condition") Condition condition);

  • sql mapping

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    <update id="updateByCondition" parameterType="map" >
      update tb_user
      set id = #{user.id,jdbcType=INTEGER},
      ...
      <if test="condition != null" >
        <include refid="Update_By_Condition_Where_Clause" />
      </if>
      <if test="_parameter != null" >
        <include refid="Update_By_Default_Where_Clause" />
      </if>

  • use #{keyname} to reference target

  • @Param(“…”) is alias manule point the map key name
  • Multi argument will auto box into a map

Collection data type

You can pass a List instance or an Array to MyBatis as a parameter object. When you do, MyBatis will automatically wrap it in a Map, and key it by name. List instances will be keyed to the name “list” and array instances will be keyed to the name “array”.

  • mapper interface

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    List<User> selectUserInList(List<Interger> ids);

  • sql mapping

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    <select id="selectUserInList" resultType="User">
      select * from user
      where id in
      <foreach item="item" index="index" collection="list"
          open="(" separator="," close=")">
            #{item}
      </foreach>
    </select>

Object’s collection

  • mapper interface

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    List<User> selectByCondition(Condition condition)

  • sql mapping

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    <where >
      <foreach collection="threshold" item="limit" separator="or" >
        <if test="limit.value > 10" >

  • threshold is a collection property in condition

  • limit represent the item in collection

link:
MyBatis input argument and parameterType