程序包 org.babyfish.jimmer

注释接口 Formula

@Retention(RUNTIME)
@Target(allowedTargets=PROPERTY)
@Target(METHOD)
public @interface Formula

This annotation is required by simple calculation property. Example1: Simple calculation based on java/kt expression

 public interface Employee {

     ... omit other properties...

     String firstName();

     String lastName();

     @Formula(dependencies = {"firstName", "lastName"})
     default String fullName() {
         return firstName() + " " + lastName();
     }

     @ManyToOne
     Department department();

     @Formula(dependencies = "department")
     default Long getDepartmentId() {
         return department() != null ? department.getId() : null;
     }
 }

Example2: Simple calculation based on SQL expression(jimmer-trigger is not used)

 public interface Employee {

     ... omit other properties...

     String firstName();

     String lastName();

     @Formula(sql = "concat(FIRST_NAME, LAST_NAME)")
     String fullName();

     @ManyToOne
     Department department();

     @Formula(sql = "DEPARTMENT_ID")
     Long getDepartmentId();
 }

Example3: Simple calculation based on SQL expression( jimmer-trigger is used and you hope the event for formula property will be raised when events for dependency properties are raised)

 public interface Employee {

     ... omit other properties...

     String firstName();

     String lastName();

     @Formula(
         sql = "concat(FIRST_NAME, LAST_NAME)",
         dependencies = {"firstName", "lastName"}
     )
     String fullName();

     @ManyToOne
     Department department();

     @Formula(
         sql = "DEPARTMENT_ID",
         dependencies = "department"
     )
     Long getDepartmentId();
 }

For complex calculation, please view Transient, `org.babyfish.jimmer.sql.TransientResolver` of jimmer-sql and `org.babyfish.jimmer.sql.kt.KTransientResolver` of jimmer-sql-kotlin

另请参阅:

• Transient

可选元素概要

可选元素

修饰符和类型	可选元素	说明
String[]	dependencies	Property names, not columns names Only need to be specified when any of the following conditions are met The decorated property is non-abstract jimmer-trigger is used and you hope the events of the dependency fields can cause the event of current field.
String	sql	When the decorated property is abstract, It means the current property a simple calculation based on sql expression The `sql` of this annotation is required In this situation, the current property will be generated in not only `Draft` and `Fetcher` but also `Table`.

元素详细资料

sql

String sql

When the decorated property is abstract,

• It means the current property a simple calculation based on sql expression
• The `sql` of this annotation is required
• In this situation, the current property will be generated in not only `Draft` and `Fetcher` but also `Table`. That means current formula property can be used by SQL-DSL
• In `Draft`, a function like `setXXX(Type value)` will generated

When the decorated property is non-abstract,

• It means the current property a simple calculation based on java/kotlin expression
• The `sql` of the annotation cannot be specified, but `dependencies` must be specified
• In this situation, the current property will be generated in not only `Draft` and `Fetcher`, but will not be generated in `Table`. That means current formula property cannot be used by SQL-DSL
• In `Draft`, a function like `useXXX()` will generated

默认值:

""

dependencies

String[] dependencies

Property names, not columns names Only need to be specified when any of the following conditions are met

• The decorated property is non-abstract
• jimmer-trigger is used and you hope the events of the dependency fields can cause the event of current field.

• For abstract formula property based on SQL expression, `dependencies` are optional, and they can only be scalar properties
• For non-abstract formula property based on java/kotlin expression, `dependencies` are required, and they can be not only scalar properties but also other formula properties. That means the formula property dependencies can be recursive

默认值:

{}