Question

我正在关注MyBatis网站中的示例创建一个具有嵌套集合的映射器，当我执行select操作时，我的对象（Provider）返回但其中的集合（ProviderParameter）为空，当我去到数据库工具并应用相同的查询我得到了预期的结果（该集合也返回）。

这是我的映射器：

   <resultMap id="Provider" type="xxx.Provider">
        <result column="idProvider" property="idProvider"/>
        <result column="providerType" property="providerType"/>
        <result column="username" property="username"/>
        <result column="password" property="password"/>
        <result column="licenceInformation" property="licenseInformation"/>
        <collection property="parameters" ofType="xxx.ProviderParameter">
            <result column="idProviderParameter" property="idProviderParameter"/>
            <result column="name" property="name"/>
            <result column="value" property="value"/>
        </collection>
    </resultMap>

选择：

<select id="getProviderById" resultType="xxx.Provider">
    select P.idProvider         as idProvider
          ,P.providerType       as providerType
          ,P.username           as username
          ,P.password           as password
          ,P.licenceInformation as licenceInformation
          ,PP.idProviderParameter as idProviderParameter
          ,PP.name              as name
          ,PP.value             as value
     from [dbo].[msg_Provider] AS P 
     left outer join [dbo].[msg_ProviderParameter] AS PP on P.idProvider = PP.idProvider     
     where P.idProvider = #{idProvider}
</select>

Answer 1

我的问题是在select I put result而不是resultMap中，

所以选择应该是：

    <select id="getProviderById" resultMap="Provider">
    select P.idProvider         as idProvider
          ,P.providerType       as providerType
          ,P.username           as username
          ,P.password           as password
          ,P.licenceInformation as licenceInformation
          ,PP.idProviderParameter as idProviderParameter
          ,PP.name              as name
          ,PP.value             as value
     from [dbo].[msg_Provider] AS P 
     left outer join [dbo].[msg_ProviderParameter] AS PP on P.idProvider = PP.idProvider     
     where P.idProvider = #{idProvider}
</select>

MyBatis，集合的嵌套结果为空

1 个答案: