⭐MybatisPlus learning notes ⭐ (7) To achieve automatic filling function

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The original link⭐MybatisPlus learning notes ⭐ (7) To achieve automatic filling function

Before the order

MybatisPlus column

⭐MybatisPlus learning notes ⭐ (1) Environment setup and entry HelloWorld

⭐MybatisPlus study Notes ⭐ (2) CRUD full set of detailed explanation

⭐MybatisPlus learning notes ⭐ (3) To achieve logical deletion, paging

⭐MybatisPlus study Notes ⭐ (4) Conditional constructor Wrapper method detailed explanation

⭐MybatisPlus study notes ⭐ (five) to achieve optimistic locking mechanism

⭐MybatisPlus study Notes ⭐ (6) Code generator detailed explanation

Look at the MybatisPlus module for this link

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1, automatic filling function introduction

Some properties in common services need to be configured with some default values. MyBatis-Plus provides a plug-in to do this, namely autofill.

Notes for automatic filling function:

• The filling principle is to directly set the value of the entity properties!!
• The annotation specifies that the property must have a value in the corresponding case, and that if there is no value, the entry will be null
• The default methods provided by MetaObjectHandler have a policy of not overwriting properties if they have values, and not filling properties if the fill value is null
• The field must declare the TableField annotation, and the attribute fill selects the corresponding policy. This declaration tells MyBtis-plus that the SQL field needs to be reserved for injection
• The population handler MyMetaObjectHandler needs to declare @Component or @Bean injection in Spring Boot
• The strictInsertFill or strictUpdateFill methods of the parent class must be used to distinguish the fieldfill. XXX annotation from the field name and field type
• There is no need to distinguish by anything to use the fillStrategy method of the superclass

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2. Realize automatic filling function

1. Annotate @tableField == for the properties that need to be autopopulated

@TableField(fill = FieldFill.INSERT)  // Fill on insert
private String email;

@TableField(fill = FieldFill.INSERT_UPDATE)   // Fill both insert and modify
private String lastName;
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2. Implement field filling controller and write custom filling rule ==

Realize the meta object processor interface: com. Baomidou. Mybatisplus. Core. Handlers. MetaObjectHandler

@Component
public class MyHandler implements MetaObjectHandler {

    //insert
    @Override
    public void insertFill(MetaObject metaObject) {
        this.setFieldValByName("lastName"."LastName autofill insert",metaObject);
        this.setFieldValByName("email"."Email autofill insert",metaObject);
    }

    // Update the field to be populated
    @Override
    public void updateFill(MetaObject metaObject) {
        this.setFieldValByName("email"."Email autofill and modify",metaObject); }}Copy the code

=, insert test

@Autowired
EmployeeMapper employeeMapper;


@Test
void contextLoads(a) {
    Employee employee = new Employee();
    employee.setAge(19);
    employee.setGender(0);

    int insert = employeeMapper.insert(employee);
    System.out.println(insert);
}
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3. Update tests

@Autowired
EmployeeMapper employeeMapper;


@Test
void contextLoads(a) {
    Employee employee = new Employee();
    employee.setAge(19);

    int update = employeeMapper.update(employee,new QueryWrapper<Employee>().eq("gender".1));
    System.out.println(update);
}
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The last

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