Mybatis-Plus common annotations

Table of contents

Mybatis-Plus common annotations

1. @TableName

2、@TableId

2.1 IdType

3、@TableField

4、@Version

5、@EnumValue

6、@TableLogic

7、@KeySequence

8、@OrderBy

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Mybatis-Plus common annotations

1. @TableName

• Description: Table name annotation, identifying the table corresponding to the entity class
• Where to use: Entity class

@TableName("sys_user")
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

 

Attributes	type	Must be specified	default value	describe
value	String	no	""	Table Name
schema	String	no	""	schema
keepGlobalPrefix	boolean	no	false	Whether to keep using the global tablePrefix value (when the global tablePrefix is ​​in effect)
resultMap	String	no	""	The id of resultMap in xml (used to satisfy specific types of entity class object binding)
autoResultMap	boolean	no	false	Whether to automatically build and use resultMap (if resultMap is set, automatic construction and injection of resultMap will not be performed)
excludeProperty	String[]	no	{}	Attribute names to be excluded

Description about  autoResultMap :

MP will automatically build one  resultMap and inject it into MyBatis (generally not used), please note the following:

Because the bottom layer of MP is MyBatis, MP just helps you inject commonly used CRUD into MyBatis. Before the injection, it is dynamic (changes according to your Entity fields and annotations), but after the injection, it is static (equal to the content in the XML configuration ).

For  typeHandler attributes, MyBatis only supports writing in 2 places:

1. Defined in resultMap, used to encapsulate query results
2. Defined   after  the insert and  update statement   (for example: ), and only applies to the current #{property}property#{property,typehandler=xxx.xxx.xxx}设置值

In addition to the above two directly specified  typeHandler forms, MyBatis has a configuration for global scanning of custom  packages. The principle is  to find the corresponding one  typeHandler according to your  type  and use it.propertytypeHandler

2、@TableId

• Description: Primary key annotation
• Where to use: Entity class primary key field

@TableName("sys_user")
public class User {
    @TableId
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

Attributes	type	Must be specified	default value	describe
value	String	no	""	Primary key field name
type	Enum	no	IdType.NONE	Specify primary key type

2.1 IdType

Attributes	illustrate
AUTO	Database ID auto-increment
NONE	Stateless, this type has no primary key set (the annotation is equivalent to following the global, and the global Rio is approximately equal to INPUT)
INPUT	Set the primary key value before inserting
ASSIGN_ID	Assign ID (primary key type is Number (Long and Integer) or String) (since 3.3.0), use the interface IdentifierGeneratormethod nextId(the default implementation class is DefaultIdentifierGeneratorSnowflake algorithm)
ASSIGN_UUID	Assign UUID, primary key type is String (since 3.3.0), use interface IdentifierGeneratormethod nextUUID(default default method)

3、@TableField

• Description: Field annotation (non-primary key)

@TableName("sys_user")
public class User {
    @TableId
    private Long id;
    @TableField("nickname")
    private String name;
    private Integer age;
    private String email;
}

Attributes	type	Must be specified	default value	describe
value	String	no	""	Database field name
exist	boolean	no	true	Whether it is a database table field
condition	String	no	""	Field  where entity query comparison conditions. If there is a value set, the set value will prevail. If not, it will be global by default  %s=#{%s}. Please refer to (opens new window)
update	String	no	""	Field  update set partial injection, for example: when annotating the version field to update="%s+1" indicate an update  set version=version+1 (this attribute has higher priority than  el the attribute)
insertStrategy	Enum	no	FieldStrategy.DEFAULT	Example: NOT_NULL insert into table_a(<if test="columnProperty != null">column</if>) values (<if test="columnProperty != null">#{columnProperty}</if>)
updateStrategy	Enum	否	FieldStrategy.DEFAULT	举例：IGNORED update table_a set column=#{columnProperty}
whereStrategy	Enum	否	FieldStrategy.DEFAULT	举例：NOT_EMPTY where <if test="columnProperty != null and columnProperty!=''">column=#{columnProperty}</if>
fill	Enum	否	FieldFill.DEFAULT	字段自动填充策略
select	boolean	否	true	是否进行 select 查询
keepGlobalFormat	boolean	否	false	是否保持使用全局的 format 进行处理
jdbcType	JdbcType	否	JdbcType.UNDEFINED	JDBC 类型 (该默认值不代表会按照该值生效)
typeHandler	Class<? extends TypeHandler>	否	UnknownTypeHandler.class	类型处理器 (该默认值不代表会按照该值生效)
numericScale	String	否	""	指定小数点后保留的位数

 注意：

关于`jdbcType`和`typeHandler`以及`numericScale`的说明:

numericScale只生效于 update 的 sql. jdbcType和typeHandler如果不配合@TableName#autoResultMap = true一起使用,也只生效于 update 的 sql. 对于typeHandler如果你的字段类型和 set 进去的类型为equals关系,则只需要让你的typeHandler让 Mybatis 加载到即可,不需要使用注解

FieldStrategy：

值	描述
IGNORED	忽略判断
NOT_NULL	非 NULL 判断
NOT_EMPTY	非空判断(只对字符串类型字段,其他类型字段依然为非 NULL 判断)
DEFAULT	追随全局配置
NEVER	不加入SQL

 FieldFill：

值	描述
DEFAULT	默认不处理
INSERT	插入时填充字段
UPDATE	更新时填充字段
INSERT_UPDATE	插入和更新时填充字段

4、@Version

描述：乐观锁注解、标记 @Version 在字段上

5、@EnumValue

描述：普通枚举类注解(注解在枚举字段上)

6、@TableLogic

Description: Table field logical processing annotations (logical deletion)

Attributes	type	Must be specified	default value	describe
value	String	no	""	logical undeleted value
delval	String	no	""	tombstone value

7、@KeySequence

• Description: Sequence primary key strategy oracle
• Attributes: value, dbType

Attributes	type	Must be specified	default value	describe
value	String	no	""	sequence name
dbType	Enum	no	DbType.OTHER	Database type. If not configured, the default implementation is to inject IKeyGenerator. Multiple implementations must be specified.

8、@OrderBy

Description: Built-in SQL specifies sorting by default, with a priority lower than wrapper conditional query

Attributes	type	Must be specified	default value	describe
isDesc	boolean	no	true	Whether to query in reverse order
sort	short	no	Short.MAX_VALUE	The smaller the number, the higher it is

 

 Reference: Annotations | MyBatis-Plus