用Nsexpression崩溃而不是其谓词建造的嵌套子征服
我有一些代码可以递归地使用nsComparisonPredicate和nsexpression。这是平坦的时候：
// Nested subquery
let entityPath = NSExpression(forKeyPath: "$s.mainUserResult.operations")
let subQueryExpression = NSExpression(forSubquery: entityPath, usingIteratorVariable: "t", predicate: NSPredicate(format: "$t.operationType == 3"))
let countSubQuery = NSExpression(format: "%@.@count", argumentArray: [subQueryExpression])
let p1 = NSComparisonPredicate(leftExpression: countSubQuery,
rightExpression: NSExpression(forConstantValue: 0),
modifier: .direct,
type: .greaterThan,
options: NSComparisonPredicate.Options(rawValue: 0))
// Main subquery
let entityPath2 = NSExpression(forKeyPath: "sessions")
let subQueryExpression2 = NSExpression(forSubquery: entityPath2, usingIteratorVariable: "s", predicate: p1)
let countSubQuery2 = NSExpression(format: "%@.@count", argumentArray: [subQueryExpression2])
let p2 = NSComparisonPredicate(leftExpression: countSubQuery2,
rightExpression: NSExpression(forConstantValue: 0),
modifier: .direct,
type: .greaterThan,
options: NSComparisonPredicate.Options(rawValue: 0))
上面的代码崩溃时，当我获取以下错误的某些实体时：
由于未被发现的例外，终止应用程序 “ nsinvalidargumentException”，原因：'不能具有无关关系 子Quemysubquery中的收集元件（$ S.Mainuserresult. $ t，$ t.operationType == 3）'
$ t ，
用谓词p2获取错误，而使用结果格式进行获取：
let p2 = NSPredicate(format: "SUBQUERY(sessions, $s, SUBQUERY($s.mainUserResult.operations, $t, $t.operationType == 3).@count > 0).@count > 0")
如何使nscomparisonPredicate工作？
I have some code that can recursively build nested subqueries with NSComparisonPredicate and NSExpression. Here it is when it's flat:
// Nested subquery
let entityPath = NSExpression(forKeyPath: "$s.mainUserResult.operations")
let subQueryExpression = NSExpression(forSubquery: entityPath, usingIteratorVariable: "t", predicate: NSPredicate(format: "$t.operationType == 3"))
let countSubQuery = NSExpression(format: "%@.@count", argumentArray: [subQueryExpression])
let p1 = NSComparisonPredicate(leftExpression: countSubQuery,
rightExpression: NSExpression(forConstantValue: 0),
modifier: .direct,
type: .greaterThan,
options: NSComparisonPredicate.Options(rawValue: 0))
// Main subquery
let entityPath2 = NSExpression(forKeyPath: "sessions")
let subQueryExpression2 = NSExpression(forSubquery: entityPath2, usingIteratorVariable: "s", predicate: p1)
let countSubQuery2 = NSExpression(format: "%@.@count", argumentArray: [subQueryExpression2])
let p2 = NSComparisonPredicate(leftExpression: countSubQuery2,
rightExpression: NSExpression(forConstantValue: 0),
modifier: .direct,
type: .greaterThan,
options: NSComparisonPredicate.Options(rawValue: 0))
The above code crashes when I fetch some entities with the following error:
Terminating app due to uncaught exception
'NSInvalidArgumentException', reason: 'Can't have a non-relationship
collection element in a subquerySUBQUERY($s.mainUserResult.operations,
$t, $t.operationType == 3)'
What's really weird is that when I build a predicate by hand by copying the resulted predicateFormat of the NSComparisonPredicate, it actually works!
Fetching with the predicate p2 results in an error, whereas fetching with the resulted format works:
let p2 = NSPredicate(format: "SUBQUERY(sessions, $s, SUBQUERY($s.mainUserResult.operations, $t, $t.operationType == 3).@count > 0).@count > 0")
How to make the NSComparisonPredicate work?
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nsexpression（forkeypath：“ $ s.mainuserresult.operations”）die
self.value（forkeypath：“ $ s.mainuserresult.operations operations''）这应该是
ss .value（forkeypath：“ mainuserresult.operations”）表达式：
nsexpression（格式：“ $ s.mainuserresult.operations”，grognnArray：[]））>NSExpression(forKeyPath: "$s.mainUserResult.operations")does
self.value(forKeyPath: "$s.mainUserResult.operations")This should be
s.value(forKeyPath: "mainUserResult.operations")expression:
NSExpression(format: "$s.mainUserResult.operations", argumentArray: [])