在 Kotlin 中为两个以上的房间实体创建关系

如何解决在 Kotlin 中为两个以上的房间实体创建关系

我正在开发具有 4 个实体的作业管理器应用：作业、发票、雇主和员工。我想返回所有创建的发票并能够导出为 pdf。但是在创建这些实体之间的关系时遇到了麻烦。试图研究大多数得到的只有两个实体。您的帮助将不胜感激。以下是我的实体：

@Entity(tableName = "invoice_tbl") 数据类发票（ @PrimaryKey(autoGenerate = false) @ColumnInfo(name = "发票名称") val 发票名称：字符串，

@ColumnInfo(name = "employerName")
val employer: String,@ColumnInfo(name = "employeeName")
val employee: String,@ColumnInfo(name = "employerCode")
val employerCode: String,@ColumnInfo(name = "dateEdited")
val dateEdited: String

)

@Entity(tableName = "employer_tbl") 数据类雇主（ @ColumnInfo(name = "雇主名称") val 雇主：字符串，

@ColumnInfo(name = "employerAddress")
val employerAddress: String,@ColumnInfo(name = "employerEmail")
val employerEmailAddress: String,@ColumnInfo(name = "employerContact")
val employerContact: String,@PrimaryKey(autoGenerate = false)
@ColumnInfo(name = "employerCode")
val employerCode: String

)

@Entity(tableName = "employee_tbl") 数据类员工（ @PrimaryKey(autoGenerate = false) @ColumnInfo(name = "employeeName") val 员工：字符串，

@ColumnInfo(name = "employeeAddress")
val employeeAddress: String,@ColumnInfo(name = "employeeEmail")
val employeeEmailAddress: String,@ColumnInfo(name = "employeeContact")
val employeeContact: String

)

@Entity(tableName = "Jobs_Table") 数据类 Job ( @ColumnInfo(name = "jobCategory") val 类别：字符串，

@ColumnInfo(name = "jobTitle")
val title: String,@PrimaryKey(autoGenerate = false)
@ColumnInfo(name = "employerName")
val employer: String,@ColumnInfo(name = "completionDate")
val completionDate: String,@ColumnInfo(name = "price")
val price: Double = 0.0,@ColumnInfo(name = "completionStatus")
val completionStatus: String,@ColumnInfo(name = "paymentStatus")
val payment: String

)

关系 @Entity(primaryKeys = [ "雇主代码","雇主名称",“员工姓名”， “发票名称” ]) 数据类 InvoiceJobEmployerEmployeeCrossRef ( val 发票名称：字符串， val 雇主名称：字符串， val 员工姓名：字符串， val 雇主代码：字符串 )

数据类 InvoiceWithJobEmployerEmployee( @Embedded val 发票：发票， @关系（ parentColumn = "发票名称",entityColumn = "员工姓名",AssociateBy = Junction(InvoiceJobEmployerEmployeeCrossRef::class) ) val allInvoices：列表 )