我有一个模型与关系属性文章的类别是一个NSOrderedSet。 现在我想要得到与在一定条件满足的文章的所有类别,在SQL我会写:一对多过滤器导航属性
SELECT *
FROM Category AS cat
JOIN Article AS art ON art.categoryId = cat.categoryId AND art.gender='m';
我试着用:
NSPredicate(format: "articles.gender like %@ OR articles.gender = %@", gender.lowercased(), "n")
我收到以下错误:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'to-many key not allowed here'
完整代码:
let ctx = self.Context()
var gender = UserDefaults.standard.string(forKey: "gender_preference") ?? "*"
if gender.uppercased() == "N" { gender = "*" }
// Create Fetch Request
let fetchRequest: NSFetchRequest = ArticleCategory.fetchRequest()
let predicate = NSPredicate(format: "articles.gender like %@ or articles.gender = %@", gender, "n")
fetchRequest.predicate = predicate
// sort by name
let sort = NSSortDescriptor(key: "name", ascending: true)
fetchRequest.sortDescriptors = [sort]
do {
let result = try ctx.fetch(fetchRequest)
return result
} catch {
print(error)
}
return []
亲切的问候
编辑:
你试过用'ANY'? 'NSPredicate(format:“ANY articles.gender like%@ OR articles.gender =%@”,gender.lowercased(),“n”)' – mat
对不起,是的,我试过了,对于一些和所有的都一样 – Mario