我如何传递参数并在mybatis动态查询创建中对其进行检查

问题描述

我在mapper.xml

<select id="getCatCount" parameterType="String" resultType="int">
    select count(*) from Categories where status is not null
    <if test="catTypeId != 0">
    AND cat_type_id = #{catTypeId,jdbcType=INTEGER}
    </if>
</select>

并且在mapper.java方法中是

and in mapper.java method is

int getCatCount(int catTypeId);

如何在条件中检查catTypeId.我知道上面的语句是不正确的，但是我想放置这样的条件，所以我检查catTypeId是否不为零，然后仅添加AND条件.还是我需要传递Category类的整个对象?

How can I check for catTypeId in if condition. I know the above statement is incorrect but I want to put condition like this so I check if catTypeId not zero then only add AND condition. Or do I need to pass whole object of Category class?

推荐答案

您不需要传递整个Category类.只需按照您的描述进行操作即可:

You do not need to pass the whole Category class. Just do it as you described:

int getCatCount(int catTypeId);

您的mapper.xml应该如下所示:

Your mapper.xml should look like this:

<select id="getCatCount" parameterClass="map" resultType="int">
  select count(*) from Categories where status is not null
   <if test="param1 != 0">
     AND cat_type_id = #{param1,jdbcType=INTEGER}
   </if>
</select>

请注意，作为parameterClass，您需要指定地图.

Notice that as parameterClass you need to specify a map.

假设现在您要传递两个参数:

Let's say that now, you want to pass two parameters:

int getCatCount(int catTypeId, int mySecondParam);

在映射器中，您应该使用param1和param2

In the mapper, you should work with param1 and param2

请参阅如何使用"paramX"命名法.但是，可以说，您要使用该命名法，而要使用自定义的参数名称作为"catTypeId".为此，在Java代码中，您需要执行以下操作:

See, how you need to use "paramX" nomenclature. But let's say, that instead using that nomenclature, you would like to use a customized parameter name as "catTypeId". For that, in you Java code you need to do this:

int getCatCount( @Param("cat_type_id ") String cat_type_id);

我将介绍XML映射器，但是使用cat_type_id代替param1.

The XML mapper would be the one that I put it about, but using cat_type_id instead param1.

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