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Annotation of Examples/EnterpriseObjects/MasteringDetails/EOFExtensions.subproj/ResetRelationships.m, revision 1.1

1.1     ! root        1: /* ResetRelationships.m created by cfeder on Thu 15-Dec-1994 */
        !             2: 
        !             3: #import "ResetRelationships.h"
        !             4: #import "ValueForKey.h"
        !             5: #import "RelationshipKeySetter.h"
        !             6: 
        !             7: @implementation EODatabaseChannel (setForeignKey)
        !             8: - objectForPrimaryKey:(NSDictionary *)key entity:(EOEntity *)entity
        !             9:     // returns existing object instance if there is one, or a fault otherwise
        !            10: {
        !            11:     EODatabaseContext *context = [self databaseContext];
        !            12:     id object = [context objectForPrimaryKey:key entity:entity];
        !            13:     if (!object) {
        !            14:         object = [EOFault objectFaultWithPrimaryKey:key
        !            15:             entity:entity databaseChannel:self zone:[self zone]];
        !            16:     }
        !            17:     return object;
        !            18: }
        !            19: 
        !            20: - fetchObjectDescribedByQualifier:(EOQualifier *)qualifier
        !            21:     // raises if not to-one.
        !            22: {
        !            23:     BOOL success, autoTransaction = NO;
        !            24:     EODatabaseContext *context = [self databaseContext];
        !            25:     NSZone *zone = [self zone];
        !            26:     id object;
        !            27: 
        !            28:     if (![context transactionNestingLevel]) {
        !            29:         [context beginTransaction];
        !            30:         autoTransaction = YES;
        !            31:     }
        !            32: 
        !            33:     success = [self selectObjectsDescribedByQualifier:qualifier
        !            34:         fetchOrder:nil];
        !            35:     object = [self fetchWithZone:zone];
        !            36:     if (!success || !object || [self fetchWithZone:zone]) {
        !            37:         [self cancelFetch];
        !            38:         [NSException raise:NSInternalInconsistencyException format:@"%s: error fetching object", sel_getName(_cmd)];
        !            39:     }
        !            40: 
        !            41:     if (autoTransaction) [context commitTransaction];
        !            42:     return object;
        !            43: }
        !            44: 
        !            45: - destinationObjectForRelationship:relationship sourceObject:sourceObject
        !            46:     // look up an exising fault, or create a new one
        !            47: {
        !            48:     id object;
        !            49:     // EODatabase *database = [[self databaseContext] database];
        !            50: 
        !            51:     if ([relationship isToMany]) {
        !            52:         // EOF doesn't unique faults, so we just have to construct a new one
        !            53:         EOQualifier *qual = [EOQualifier qualifierForObject:sourceObject relationship:relationship];
        !            54:         object = [EOFault arrayFaultWithQualifier:qual
        !            55:             fetchOrder:nil databaseChannel:self zone:[self zone]];
        !            56:     } else {
        !            57:         // see if this is already in the uniquing table
        !            58:         if ([relationship isFlattened]) {
        !            59:             EOQualifier *qual = [EOQualifier qualifierForObject:sourceObject relationship:relationship];
        !            60: 
        !            61:             // should fetch object from channel with qualifier
        !            62:             object = [self fetchObjectDescribedByQualifier:qual];
        !            63:         } else {
        !            64:             // for to-ones, the primary key is always the destination of the
        !            65:             // relationship
        !            66:             NSDictionary *pk = [relationship destinationValuesFromSourceObject:sourceObject];
        !            67:             object = [self objectForPrimaryKey:pk entity:[relationship destinationEntity]];
        !            68:         }
        !            69:     }
        !            70:     return object;
        !            71: }
        !            72: 
        !            73: - (void)updateRelationshipsInObject:object forModifiedAttributes:(NSArray *)attributes
        !            74:    // After the values in object corresponding to the EOAttributes
        !            75:    // in the "attributes" array have been update (perhaps with 
        !            76:    // takeValuesFromDictionary) this method can be called to update any
        !            77:    // corresponding relationship properties.  So, if a foreign dept_id
        !            78:    // attribute way modified in a employee object, this would attempt to
        !            79:    // reset the "toDepartment" property to point at the corresponding
        !            80:    // department object.
        !            81: {
        !            82:     // We should apply some caching here to make this fast.  I.e. map directly
        !            83:     // from attribute to list of class property relationships that this participates in.
        !            84:     // For now we'll just be simple and slow.
        !            85:     NSMutableArray *affectedRelationships = [NSMutableArray array];
        !            86:     EOModel *model = [[[[self databaseContext] database] adaptor] model];
        !            87:     EOEntity *entity = [model entityForObject:object];
        !            88:     NSArray *classProperties = [entity classProperties];
        !            89:     NSArray *relationships = [entity relationships];
        !            90:     int i,count = [relationships count];
        !            91: 
        !            92:     for(i=0; i<count; i++) {
        !            93:         EORelationship *relationship = [relationships objectAtIndex:i];
        !            94: 
        !            95:         if ([classProperties indexOfObjectIdenticalTo:relationship] != NSNotFound) {
        !            96:             NSArray *joins = [relationship joins];
        !            97:             int j, jcount = [joins count];
        !            98: 
        !            99:             for (j = 0; j < jcount; j++) {
        !           100:                 EOJoin *join = [joins objectAtIndex:j];
        !           101:                 if ([attributes indexOfObjectIdenticalTo:[join sourceAttribute]] != NSNotFound) {
        !           102:                     [affectedRelationships addObject:relationship];
        !           103:                     break;
        !           104:                 }
        !           105:             }
        !           106:         }
        !           107:     }
        !           108: 
        !           109:     // We now have a list of affected relationships that we need to retarget
        !           110:     {
        !           111:         count = [affectedRelationships count];
        !           112:         for(i=0; i<count; i++) {
        !           113:             EORelationship *relationship = [relationships objectAtIndex:i];
        !           114:             id dest = [self destinationObjectForRelationship:relationship sourceObject:object];
        !           115:             [object takeValue:dest forKey:[relationship name]];
        !           116:         }
        !           117:     }
        !           118: }
        !           119: @end

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