Many-to-many relations

[saschaholesch]

Are many-to-many relationships supported as well? Or only one-to-many?

Example:

• A user can be in many groups
• A group can hold many users

or

• An item has many tags and
• A tag has many items

Would that be a problem?

[saschaholesch]

Hi. I tried Seam, but get these NSMergeConflict errors and the App will crash. Could this be related to my question above?

2015-10-03 22:12:16.919 atsumeru2-ios[190:4977] Unresolved error Error Domain=NSCocoaErrorDomain Code=133020 "Could not merge changes." UserInfo={conflictList=(
    "NSMergeConflict (0x178154d0) for NSManagedObject (0x167c18a0) with objectID '0x167c4640 <x-coredata://32D12AFB-E488-41C9-A96F-C889479BC1D0/Item/p1>' with oldVersion = 1 and newVersion = 2 and old object snapshot = {\n    favorite = 0;\n    key = 42A6952;\n    lastViewed = \"2046-10-03 13:11:18 +0000\";\n    orderingValue = 1;\n    \"sm_LocalStore_EncodedValues\" = \"<null>\";\n    \"sm_LocalStore_RecordID\" = \"68B820C4-4B57-4080-BD1D-0D8A2224C09D\";\n    title = unnamed;\n    type = \"mytype\";\n} and new cached row = {\n    favorite = 0;\n    key = 42A6952;\n    lastViewed = \"2046-10-03 13:11:18 +0000\";\n    orderingValue = 1;\n    \"sm_LocalStore_EncodedValues\" = <62706c69 73743030 d4010203 04053069 6a542474 6f705824 6f626a65 63747358 24766572 73696f6e 59246172 63686976 6572df10 15060708 090a0b0c 0d0e0f10 11121314 15161718 191a1b1c 1d1c1c20 211c1d1c 251c1c28 292a2b1c 2d1c2f5b 5265636f 72644d74 696d655b 46616b65 53686172 65494459 57617343 61636865 64575368 61726549 445f100f 50726576 696f7573 53686172 6549445a 5265636f 72645479 70655f10 104d6f64 69666965 64427944 65766963 655f1012 436f6e66 6c696374 4c6f7365 72457461 67735f10 11486173 55706461 74656453 68617265 49445f10 1a507265 76696f75 7350726f 74656374 696f6e44 61746145 7461675f 10134372 6561746f 72557365 72526563 6f726449 445f1016 5a6f6e65 50726f74 65637469 6f6e4461 74614574 61675e50 726f7465 6374696f 6e446174 61585265 636f7264 49445b52 65636f72 64437469 6d655445 5461675d 4b6e6f77 6e546f53 65727665 725f1017 53686172 6550726f 74656374 696f6e44 61746145 7461675a 5065726d 69737369 6f6e5f10 1250726f 74656374 696f6e44 61746145 7461675f 10184c61 73744d6f 64696669 65645573 65725265 636f7264 4944800b 80000880 00800080 01801380 00088000 800c8000 80008002 80098012 09800010 01800080 10af1014 3132333a 3b414243 4a4e5255 585c5d61 62666768 55246e75 6c6c5449 74656dd3 34353637 3839565a 6f6e6549 44562463 6c617373 5a526563 6f72644e 616d6580 04800880 035f1024 36384238 32304334 2d344235 372d3430 38302d42 4431442d 30443841 32323234 43303944 d33c3d35 3e3f4059 6f776e65 724e616d 65585a6f 6e654e61 6d658006 80058007 5f101c53 4d53746f 7265436c 6f756453 746f7265 5f437573 746f6d5a 6f6e655f 10105f5f 64656661 756c744f 776e6572 5f5fd244 45464958 24636c61 73736573 5a24636c 6173736e 616d65a2 47485e43 4b526563 6f72645a 6f6e6549 44584e53 4f626a65 63745e43 4b526563 6f72645a 6f6e6549 44d24445 4b4da24c 485a434b 5265636f 72644944 5a434b52 65636f72 644944d2 354f5051 574e532e 74696d65 800a2341 bbc00b77 ef1aa0d2 44455354 a2544856 4e534461 7465d235 4f505780 0a2341bb c00b77ef 1aa0d334 35365938 5b800e80 08800d5f 10105f5f 64656661 756c744f 776e6572 5f5fd33c 3d353e5f 40800680 0f80075c 5f646566 61756c74 5a6f6e65 d3343536 59386580 0e800880 115f1010 5f5f6465 6661756c 744f776e 65725f5f 5231366f 10190053 00610073 00630068 00610020 004d0020 0048006f 006c0065 00730063 00682019 00730020 00690050 0068006f 006e0065 12000186 a05f100f 4e534b65 79656441 72636869 76657200 08001100 16001f00 28003200 5f006b00 77008100 89009b00 a600b900 ce00e200 ff011501 2e013d01 46015201 57016501 7f018a01 9f01ba01 bc01be01 bf01c101 c301c501 c701c901 ca01cc01 ce01d001 d201d401 d601d801 d901db01 dd01df01 e101f801 fe020302 0a021102 18022302 25022702 29025002 57026102 6a026c02 6e027002 8f02a202 a702b002 bb02be02 cd02d602 e502ea02 ed02f803 03030803 10031203 1b032003 23032a03 2f033103 3a034103 43034503 47035a03 61036303 65036703 74037b03 7d037f03 81039403 9703cc03 d1000000 00000002 01000000 00000000 6b000000 00000000 00000000 00000003 e3>;\n    \"sm_LocalStore_RecordID\" = \"68B820C4-4B57-4080-BD1D-0D8A2224C09D\";\n    title = unnamed;\n    type = \"mytype\";\n}"
)}, [conflictList: (
    "NSMergeConflict (0x178154d0) for NSManagedObject (0x167c18a0) with objectID '0x167c4640 <x-coredata://32D12AFB-E488-41C9-A96F-C889479BC1D0/Item/p1>' with oldVersion = 1 and newVersion = 2 and old object snapshot = {\n    favorite = 0;\n    key = 42A6952;\n    lastViewed = \"2046-10-03 13:11:18 +0000\";\n    orderingValue = 1;\n    \"sm_LocalStore_EncodedValues\" = \"<null>\";\n    \"sm_LocalStore_RecordID\" = \"68B820C4-4B57-4080-BD1D-0D8A2224C09D\";\n    title = unnamed;\n    type = \"mytype\";\n} and new cached row = {\n    favorite = 0;\n    key = 42A6952;\n    lastViewed = \"2046-10-03 13:11:18 +0000\";\n    orderingValue = 1;\n    \"sm_LocalStore_EncodedValues\" = <62706c69 73743030 d4010203 04053069 6a542474 6f705824 6f626a65 63747358 24766572 73696f6e 59246172 63686976 6572df10 15060708 090a0b0c 0d0e0f10 11121314 15161718 191a1b1c 1d1c1c20 211c1d1c 251c1c28 292a2b1c 2d1c2f5b 5265636f 72644d74 696d655b 46616b65 53686172 65494459 57617343 61636865 64575368 61726549 445f100f 50726576 696f7573 53686172 6549445a 5265636f 72645479 70655f10 104d6f64 69666965 64427944 65766963 655f1012 436f6e66 6c696374 4c6f7365 72457461 67735f10 11486173 55706461 74656453 68617265 49445f10 1a507265 76696f75 7350726f 74656374 696f6e44 61746145 7461675f 10134372 6561746f 72557365 72526563 6f726449 445f1016 5a6f6e65 50726f74 65637469 6f6e4461 74614574 61675e50 726f7465 6374696f 6e446174 61585265 636f7264 49445b52 65636f72 64437469 6d655445 5461675d 4b6e6f77 6e546f53 65727665 725f1017 53686172 6550726f 74656374 696f6e44 61746145 7461675a 5065726d 69737369 6f6e5f10 1250726f 74656374 696f6e44 61746145 7461675f 10184c61 73744d6f 64696669 65645573 65725265 636f7264 4944800b 80000880 00800080 01801380 00088000 800c8000 80008002 80098012 09800010 01800080 10af1014 3132333a 3b414243 4a4e5255 585c5d61 62666768 55246e75 6c6c5449 74656dd3 34353637 3839565a 6f6e6549 44562463 6c617373 5a526563 6f72644e 616d6580 04800880 035f1024 36384238 32304334 2d344235 372d3430 38302d42 4431442d 30443841 32323234 43303944 d33c3d35 3e3f4059 6f776e65 724e616d 65585a6f 6e654e61 6d658006 80058007 5f101c53 4d53746f 7265436c 6f756453 746f7265 5f437573 746f6d5a 6f6e655f 10105f5f 64656661 756c744f 776e6572 5f5fd244 45464958 24636c61 73736573 5a24636c 6173736e 616d65a2 47485e43 4b526563 6f72645a 6f6e6549 44584e53 4f626a65 63745e43 4b526563 6f72645a 6f6e6549 44d24445 4b4da24c 485a434b 5265636f 72644944 5a434b52 65636f72 644944d2 354f5051 574e532e 74696d65 800a2341 bbc00b77 ef1aa0d2 44455354 a2544856 4e534461 7465d235 4f505780 0a2341bb c00b77ef 1aa0d334 35365938 5b800e80 08800d5f 10105f5f 64656661 756c744f 776e6572 5f5fd33c 3d353e5f 40800680 0f80075c 5f646566 61756c74 5a6f6e65 d3343536 59386580 0e800880 115f1010 5f5f6465 6661756c 744f776e 65725f5f 5231366f 10190053 00610073 00630068 00610020 004d0020 0048006f 006c0065 00730063 00682019 00730020 00690050 0068006f 006e0065 12000186 a05f100f 4e534b65 79656441 72636869 76657200 08001100 16001f00 28003200 5f006b00 77008100 89009b00 a600b900 ce00e200 ff011501 2e013d01 46015201 57016501 7f018a01 9f01ba01 bc01be01 bf01c101 c301c501 c701c901 ca01cc01 ce01d001 d201d401 d601d801 d901db01 dd01df01 e101f801 fe020302 0a021102 18022302 25022702 29025002 57026102 6a026c02 6e027002 8f02a202 a702b002 bb02be02 cd02d602 e502ea02 ed02f803 03030803 10031203 1b032003 23032a03 2f033103 3a034103 43034503 47035a03 61036303 65036703 74037b03 7d037f03 81039403 9703cc03 d1000000 00000002 01000000 00000000 6b000000 00000000 00000000 00000003 e3>;\n    \"sm_LocalStore_RecordID\" = \"68B820C4-4B57-4080-BD1D-0D8A2224C09D\";\n    title = unnamed;\n    type = \"mytype\";\n}"
)]