Mybatis dynamic sql

這次專案是對既有的DB資料來開發系統，用到 Mybatis的generator 和dynamic sql 產生mapper及sql語法(不用寫任何的xml及欄位對應)  其中selectByExample 是對所有欄位都取出，但條件是依照web UI所輸入的欄位動態產生where condition，isEqualToWhenPresent就是當參數非null才會產生該條件，另外一個需求是需透過程式的if condition來動態加上條件。這些寫法也是透過官網的範例逐一摸索出來的，給有需要的人參考看看。

import static org.mybatis.dynamic.sql.SqlBuilder.isEqualToWhenPresent;
import static org.mybatis.dynamic.sql.SqlBuilder.isIn;
import static org.mybatis.dynamic.sql.SqlBuilder.isNull;
import org.mybatis.dynamic.sql.select.MyBatis3SelectModelAdapter;
import org.mybatis.dynamic.sql.select.QueryExpressionDSL;
...

@Override
 public Optional> searchEmployees(EmployeeCondition byCondition) {
                 QueryExpressionDSL>>.QueryExpressionWhereBuilder dsl =mapper.selectByExample()
               .where(BpsnDynamicSqlSupport.bpeno, isEqualToWhenPresent(byCondition.getBpeno()))
               .and(BpsnDynamicSqlSupport.alias, isEqualToWhenPresent(byCondition.getAlias()))
               .and(BpsnDynamicSqlSupport.bpnme, isEqualToWhenPresent(byCondition.getBpnme()))
               .and(BpsnDynamicSqlSupport.mobile1, isEqualToWhenPresent(byCondition.getMobile1()))
               .and(BpsnDynamicSqlSupport.address, isEqualToWhenPresent(byCondition.getAddress()))
               .and(BpsnDynamicSqlSupport.passportno, isEqualToWhenPresent(byCondition.getPassportno()));
   
    if(EmployeeQuery.ACTIVE.equals(EmployeeQuery.valueOf(byCondition.getWorkType()))) {
     dsl.and(BpsnDynamicSqlSupport.bpedy, isNull());
   }else if(EmployeeQuery.TRANSFER.equals(EmployeeQuery.valueOf(byCondition.getWorkType()))) {
    dsl.and(BpsnDynamicSqlSupport.deptNo, isIn("L","M"));
   }
   
         List list  =  dsl.build().execute();
         return list==null ? Optional.empty() : Optional.of(list);
 }