[英]How to fetch data from core data using Entity relationship in swift?
我有两个实体“办公室”和“员工”
Office Entity属性为
officeId - string
officename - string
员工实体属性是
employeename - string
emailid - string
并且拥有多对多的关系-办公室与员工的关系是“员工”
func SaveData(){
let entityOffice = NSEntityDescription.entityForName("Office", inManagedObjectContext: context)
let newoffice = NSManagedObject(entity: entityOffice!, insertIntoManagedObjectContext: context)
newoffice.setValue("BUI001", forKey: "officeId")
newoffice.setValue("Home builders", forKey: "officename")
let entityEmployees = NSEntityDescription.entityForName("Employee", inManagedObjectContext:context)
let newemploy = NSManagedObject(entity: entityEmployees!, insertIntoManagedObjectContext: context)
// Populate Address
newemploy.setValue("Tom william", forKey: "employeename")
newemploy.setValue("tomus@yahoo.com", forKey: "emailid")
// Add Address to Person
newoffice.setValue(NSSet(object: newemploy), forKey: "staff")
do {
try newoffice.managedObjectContext?.save()
} catch {
let saveError = error as NSError
print(saveError)
}
}
保存数据工作正常。我不知道如何在有关系的实体之间获取数据。
如何使用“ Office”实体的“ officeid”在“ Employee”实体中获取所有雇员数据。 谢谢你
您需要像这样使用NSPredicate
:
let officeId = "BUI001"
let predicate = NSPredicate(format: "ANY self.staff.officeId == %@", argumentArray: [officeId])
let fetchRequest = NSFetchRequest(entityName: "Employee")
fetchRequest.predicate = predicate
现在,将此fetchRequest与您的managedContext一起使用,以获取与officeId BUI001相关的所有员工
let fetchRequest = NSFetchRequest(entityName: “Employee”)
let predicate = NSPredicate(format:”officeId=%@”, "BUI001")
fetchRequest.predicate = predicate
if let fetchResults = try? self.managedObjectContext.executeFetchRequest(fetchRequest)
{
if fetchResults.count > 0 {
for bEntity in fetchResults {
let employeeEntity = bEntity as! EmployeeEntity
// append the details to the employeeDetails
} else
{
print(“Details Not Added")
}
}
return employeeDetails
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.