我們在開發(fā)應用時，在某些應用場景下查詢有時需要排除某些字段，mybatis-plus主要提供了以下兩種方式

1.通過@TableField()

1.1準備User類

@Data
public class User extends Model<User> {
private Long id;
private String name;
private Integer age;
private String email;
@TableField(exist = false)
private int deleted;
}

1.2 測試方法

@Test
public void testQueryPage(){
QueryWrapper<User> wrapper= new QueryWrapper<User>();
wrapper.ne("age",200) ;
Page<User> page= new Page<User>(6,20,true);
IPage<User> iPage= userMapper.selectPage(page,wrapper);
System.out.println("總頁數(shù)："+iPage.getPages()+",總記錄數(shù)："+iPage.getTotal()+",當前頁："+iPage.getCurrent());
List<User> users= iPage.getRecords();
users.forEach(System.out::println);
}

1.3測試結果

2022-10-10 11:18:10.901 DEBUG 23728 --- [ main] c.m.s.mapper.UserMapper.selectPage : ==> Preparing: SELECT id,name,age,email FROM user WHERE (age <> ?) LIMIT ?,?

2022-10-10 11:18:10.901 DEBUG 23728 --- [ main] c.m.s.mapper.UserMapper.selectPage : ==> Parameters: 200(Integer), 100(Long), 20(Long)

2022-10-10 11:18:10.911 DEBUG 23728 --- [ main] c.m.s.mapper.UserMapper.selectPage : <== Total: 14

2.通過querywrapper中的select方法來排除

2.1.具體方法內容：

public QueryWrapper<T> select(Class<T> entityClass, Predicate<TableFieldInfo> predicate) {
super.setEntityClass(entityClass);
this.sqlSelect.setStringValue(TableInfoHelper.getTableInfo(this.getEntityClass()).chooseSelect(predicate));
return (QueryWrapper)this.typedThis;
}

2.2.這里的Predicate接口有一個關鍵方法,也就意味著test方法返回ture才會展現(xiàn)這個

/**
* Evaluates this predicate on the given argument.
*
* @param t the input argument
* @return {@code true} if the input argument matches the predicate,
* otherwise {@code false}
*/
boolean test(T t);

下面我們來按排這個方法來準備

2.3 準備User類

@Data
public class User extends Model<User> {
private Long id;
private String name;
private Integer age;
private String email;
private int deleted;
}

2.4 準備測方法

@Test
public void testQueryPage(){
QueryWrapper<User> wrapper= new QueryWrapper<User>();
wrapper.ne("age",200).select(User.class,info -> !info.getColumn().equals("deleted"));
Page<User> page= new Page<User>(6,20,true);
IPage<User> iPage= userMapper.selectPage(page,wrapper);
System.out.println("總頁數(shù)："+iPage.getPages()+",總記錄數(shù)："+iPage.getTotal()+",當前頁："+iPage.getCurrent());
List<User> users= iPage.getRecords();
users.forEach(System.out::println);
}

2.5運行l(wèi)og

2022-10-10 11:22:04.720 DEBUG 20580 --- [ main] c.m.s.m.UserMapper.selectPage_mpCount : ==> Preparing: SELECT COUNT(*) AS total FROM user WHERE deleted = 0 AND (age <> ?)

2022-10-10 11:22:04.750 DEBUG 20580 --- [ main] c.m.s.m.UserMapper.selectPage_mpCount : ==> Parameters: 200(Integer)

2022-10-10 11:22:04.780 DEBUG 20580 --- [ main] c.m.s.m.UserMapper.selectPage_mpCount : <== Total: 1

2022-10-10 11:22:04.791 DEBUG 20580 --- [ main] c.m.s.mapper.UserMapper.selectPage : ==> Preparing: SELECT id,name,age,email FROM user WHERE deleted=0 AND (age <> ?) LIMIT ?,?

2022-10-10 11:22:04.792 DEBUG 20580 --- [ main] c.m.s.mapper.UserMapper.selectPage : ==> Parameters: 200(Integer), 100(Long), 20(Long)

2022-10-10 11:22:04.796 DEBUG 20580 --- [ main] c.m.s.mapper.UserMapper.selectPage : <== Total: 13

總頁數(shù)：6,總記錄數(shù)：113,當前頁：6

User(id=197, name=zouli197, age=227, email=zoulinlin197@163.com, deleted=0)

User(id=198, name=zouli198, age=228, email=zoulinlin198@163.com, deleted=0)

User(id=199, name=zouli199, age=229, email=zoulinlin199@163.com, deleted=0)

User(id=310, name=zouli10, age=40, email=zoulinlin10@163.com, deleted=0)

如果沒有按照上面說明的方式來進行，正常測試log會有deleted字段查詢

2022-10-10 11:24:33.069 DEBUG 18760 --- [ main] c.m.s.m.UserMapper.selectPage_mpCount : ==> Preparing: SELECT COUNT(*) AS total FROM user WHERE deleted = 0 AND (age <> ?)

2022-10-10 11:24:33.089 DEBUG 18760 --- [ main] c.m.s.m.UserMapper.selectPage_mpCount : ==> Parameters: 200(Integer)

2022-10-10 11:24:33.119 DEBUG 18760 --- [ main] c.m.s.m.UserMapper.selectPage_mpCount : <== Total: 1

2022-10-10 11:24:33.129 DEBUG 18760 --- [ main] c.m.s.mapper.UserMapper.selectPage : ==> Preparing: SELECT id,name,age,email,deleted FROM user WHERE deleted=0 AND (age <> ?) LIMIT ?,?

2022-10-10 11:24:33.129 DEBUG 18760 --- [ main] c.m.s.mapper.UserMapper.selectPage : ==> Parameters: 200(Integer), 100(Long), 20(Long)

2022-10-10 11:24:33.129 DEBUG 18760 --- [ main] c.m.s.mapper.UserMapper.selectPage : <== Total: 13

總頁數(shù)：6,總記錄數(shù)：113,當前頁：6

User(id=197, name=zouli197, age=227, email=zoulinlin197@163.com, deleted=0)

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