如何在MyBatis中使用注解实现条件Where子句？

现有代码及问题 #

Service层代码 #

public List<ApplicationConfig> find(@RequestBody String type){
    List<WhereClauseParams> conditions = new ArrayList<>();
    WhereClauseParams condition = new WhereClauseParams("type", type);
    conditions.add(condition);
    return applicationConfigRepository.find(conditions);
}

public List<ApplicationConfig> findById(@RequestBody String id){
    List<WhereClauseParams> conditions = new ArrayList<>();
    WhereClauseParams condition = new WhereClauseParams("id", id);
    conditions.add(condition);
    return applicationConfigRepository.find(conditions);
}

自定义WhereClauseParams类 #

public class WhereClauseParams {
    private String column;
    private String sqlOperator = "=";
    private Object value;
    // 包含对应的getter、setter方法与构造方法
}

Mapper接口代码 #

@Repository
@Mapper
public interface ApplicationConfigRepository {
    @Select("<script>" +
            "select id, name, type, isActive, createdBy, createdOn, updatedBy, updatedOn " +
            "from application_config " +
            "where 1=1 " +
            "<if test=\"type!=null\"> " +
            " and type=#{type} " +
            " </if>" +
            "<if test=\"id!=null\"> " +
            " and id=#{id} " +
            " </if>" +
            "</script>")
    public List<ApplicationConfig> find(List<WhereClauseParams> params);
}

首次报错信息 #

org.apache.ibatis.binding.BindingException: Parameter 'type' not found. Available parameters are [collection, list, params]
...（省略完整栈信息）

尝试将Mapper中的条件改为params.type!=null，问题未解决。

修改后的尝试 #

修改后的Service层

public List<ApplicationConfig> find(@RequestBody String type){
    List<WhereClauseParams> conditions = new ArrayList<>();
    WhereClauseParams condition = new WhereClauseParams("type", type);
    conditions.add(condition);
    return applicationConfigRepository.find(Map.of("type", type));
}

public List<ApplicationConfig> findById(@RequestBody String id){
    List<WhereClauseParams> conditions = new ArrayList<>();
    WhereClauseParams condition = new WhereClauseParams("id", id);
    conditions.add(condition);
    return applicationConfigRepository.find(Map.of("id", id));
}

修改后的Mapper接口

@Select("<script>" +
        "select id, name, type, isActive, createdBy, createdOn, updatedBy, updatedOn " +
        "from application_config " +
        "where 1=1 " +
        "<if test=\"params.type!=null\"> " +
        " and type=#{params.type} " +
        " </if>" +
        "<if test=\"params.id!=null\"> " +
        " and id=#{params.id} " +
        " </if>" +
        "</script>")
public List<ApplicationConfig> find(Map params);

新报错信息 #

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: Error evaluating expression 'params.type!=null'. Cause: org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "type")
...（省略完整栈信息）

解决方案 #

方案1：简化Map参数传递 #

修改Mapper的SQL表达式，去掉多余的params.前缀，因为传递的Map直接包含type、id等键：

@Repository
@Mapper
public interface ApplicationConfigRepository {
    @Select("<script>" +
            "select id, name, type, isActive, createdBy, createdOn, updatedBy, updatedOn " +
            "from application_config " +
            "where 1=1 " +
            "<if test=\"type!=null\"> " +
            " and type=#{type} " +
            " </if>" +
            "<if test=\"id!=null\"> " +
            " and id=#{id} " +
            " </if>" +
            "</script>")
    public List<ApplicationConfig> find(Map<String, Object> params);
}

Service层保持现有传递Map的逻辑即可，无需额外修改。

方案2：复用WhereClauseParams实现动态多条件 #

如果需要支持多条件组合查询，保留WhereClauseParams设计，用MyBatis的<foreach>遍历条件列表：

1. 修改Mapper接口，用@Param明确参数名：

@Repository
@Mapper
public interface ApplicationConfigRepository {
    @Select("<script>" +
            "select id, name, type, isActive, createdBy, createdOn, updatedBy, updatedOn " +
            "from application_config " +
            "where 1=1 " +
            "<foreach collection='conditions' item='condition' separator=' and '>" +
            " ${condition.column} ${condition.sqlOperator} #{condition.value} " +
            "</foreach>" +
            "</script>")
    public List<ApplicationConfig> find(@Param("conditions") List<WhereClauseParams> conditions);
}

• 注意：column和sqlOperator用${}（直接拼接SQL，需确保参数安全，避免注入），value用#{}（预编译，防止注入）。

2. Service层恢复最初传递conditions列表的逻辑即可。

方案3：单条件场景简化实现 #

如果只是单条件查询（按type或id），直接用@Param标注单个参数：

@Repository
@Mapper
public interface ApplicationConfigRepository {
    @Select("<script>" +
            "select id, name, type, isActive, createdBy, createdOn, updatedBy, updatedOn " +
            "from application_config " +
            "where 1=1 " +
            "<if test='type != null'> and type = #{type} </if>" +
            "<if test='id != null'> and id = #{id} </if>" +
            "</script>")
    List<ApplicationConfig> find(@Param("type") String type, @Param("id") String id);
}

Service层调用时传递对应参数，比如find(type, null)或find(null, id)。

内容的提问来源于stack exchange，提问作者Abhishek Acharya