CODEWITHSUNDEEP
iosswiftcore-data
user3606682
user3606682

Reputation: 2105

Group by in core data in ios swift not working

I am php web developer. I have learnt ios swift recently. I am trying to fetch the records from core data and group the records based on one column or more appropriately based on one attribute in ios swift. I have tried the solutions from Stack Overflow but none of them are working for me. So please someone can point out what I'm doing wrong. Here is my code:

    var context : NSManagedObjectContext = appdel.managedObjectContext!

    var request = NSFetchRequest(entityName: "TblOrders")
    request.returnsObjectsAsFaults = false
    request.propertiesToGroupBy = ["order_num"]
    request.propertiesToFetch = ["cust_name", "brand"]
    request.resultType = .DictionaryResultType
    context.executeFetchRequest(request, error: nil)!
    var results = context.executeRequest(request, error: nil)!

    println(results)

And this is the error message:

2015-08-11 10:54:30.423 newapp[470:6013] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'SELECT clauses in queries with GROUP BY components can only contain properties named in the GROUP BY or aggregate functions ((<NSAttributeDescription: 0x7fa8ca5b4b70>), name cust_name, isOptional 1, isTransient 0, entity TblOrders, renamingIdentifier cust_name, validation predicates (
), warnings (
), versionHashModifier (null)
 userInfo {
}, attributeType 700 , attributeValueClassName NSString, defaultValue (null) is not in the GROUP BY)'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000101e35c65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x00000001039a0bb7 objc_exception_throw + 45
    2   CoreData                            0x0000000101a4fbbc -[NSSQLGenerator newSQLStatementForRequest:ignoreInheritance:countOnly:nestingLevel:] + 1724
    3   CoreData                            0x0000000101a3bdc4 -[NSSQLAdapter _statementForFetchRequest:ignoreInheritance:countOnly:nestingLevel:] + 244
    4   CoreData                            0x0000000101953e0c -[NSSQLAdapter _newSelectStatementWithFetchRequest:ignoreInheritance:] + 316
    5   CoreData                            0x0000000101953a86 -[NSSQLCore newRowsForFetchPlan:] + 118
    6   CoreData                            0x000000010195333c -[NSSQLCore objectsForFetchRequest:inContext:] + 524
    7   CoreData                            0x0000000101952dbb -[NSSQLCore executeRequest:withContext:error:] + 299
    8   CoreData                            0x0000000101a2da6c __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke + 3356
    9   CoreData                            0x0000000101a36c30 gutsOfBlockToNSPersistentStoreCoordinatorPerform + 192
    10  libdispatch.dylib                   0x00000001040a2614 _dispatch_client_callout + 8
    11  libdispatch.dylib                   0x0000000104088002 _dispatch_barrier_sync_f_invoke + 365
    12  CoreData                            0x0000000101a28245 _perform + 197
    13  CoreData                            0x0000000101952a58 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 504
    14  CoreData                            0x00000001019512ca -[NSManagedObjectContext executeFetchRequest:error:] + 586
    15  newapp                              0x000000010165ea9a _TFC6newapp25OrderStatusViewController11viewDidLoadfS0_FT_T_ + 1418
    16  newapp                              0x000000010165efe2 _TToFC6newapp25OrderStatusViewController11viewDidLoadfS0_FT_T_ + 34
    17  UIKit                               0x00000001028051d0 -[UIViewController loadViewIfRequired] + 738
    18  UIKit                               0x00000001028053ce -[UIViewController view] + 27
    19  UIKit                               0x000000010282a257 -[UINavigationController _startCustomTransition:] + 633
    20  UIKit                               0x000000010283637f -[UINavigationController _startDeferredTransitionIfNeeded:] + 386
    21  UIKit                               0x0000000102836ece -[UINavigationController __viewWillLayoutSubviews] + 43
    22  UIKit                               0x00000001029816d5 -[UILayoutContainerView layoutSubviews] + 202
    23  UIKit                               0x00000001027549eb -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 536
    24  QuartzCore                          0x0000000106522ed2 -[CALayer layoutSublayers] + 146
    25  QuartzCore                          0x00000001065176e6 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
    26  QuartzCore                          0x0000000106517556 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
    27  QuartzCore                          0x000000010648386e _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 242
    28  QuartzCore                          0x0000000106484a22 _ZN2CA11Transaction6commitEv + 462
    29  QuartzCore                          0x00000001064850d3 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 89
    30  CoreFoundation                      0x0000000101d68ca7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    31  CoreFoundation                      0x0000000101d68c00 __CFRunLoopDoObservers + 368
    32  CoreFoundation                      0x0000000101d5ea33 __CFRunLoopRun + 1123
    33  CoreFoundation                      0x0000000101d5e366 CFRunLoopRunSpecific + 470
    34  GraphicsServices                    0x0000000105e09a3e GSEventRunModal + 161
    35  UIKit                               0x00000001026d48c0 UIApplicationMain + 1282
    36  newapp                              0x0000000101678747 main + 135
    37  libdyld.dylib                       0x00000001040d6145 start + 1
    38  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

I have tried the solution from here: Swift Core Data - Group doesn't Work

If any further information needed please let me know.

Upvotes: 4

Views: 7765

Answers (1)

user3606682
user3606682

Reputation: 2105

Finally I could resolved the issue. Though I dont have knowledge in objective C, I have searched for the same issue in objective C and got the idea to resolve my problem in Swift. It could help someone who might be facing the same problem, so im sharing my solution here.

The issue was propertiesToGroupBy must contain all the elements which are to be fetched by propertiesToFetch. For clarity I am pasting those two lines of code separately here:

    request.propertiesToGroupBy = ["order_num","cust_name"]
    request.propertiesToFetch = ["order_num","cust_name"]

Observe the above lines of code have both elements(attributes) order_num and cust_name. (this is merely an example from my code. but we can add as many elements we want)

Here is the full code solution for my above question:

    var context : NSManagedObjectContext = appdel.managedObjectContext!
    var request = NSFetchRequest(entityName: "TblOrders")
    request.returnsObjectsAsFaults = false
    request.propertiesToGroupBy = ["order_num","cust_name"]
    request.propertiesToFetch = ["order_num","cust_name"]
    request.resultType = .DictionaryResultType
    context.executeFetchRequest(request, error: nil)!
    var res = context.executeFetchRequest(request, error: nil)!
    var results = res as NSArray
    println(results)

Upvotes: 10

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