iOS FMDatabase wrapper, initialising issue??

[mraheel]

Hi guys,

I've run into a simple complication, I dont think i got how FMDatabase can be initialised and used throughout the application in similar ways of Sqlite.

For example,

	NSString *path = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"database.sqlite"];

FMDatabase *newDB = [FMDatabase databaseWithPath:path];

if (![newDB open]) {
	}
FMResultSet *rs = [newDB executeQuery:@"select * from tap where id=?",  @"2"];
		if ([newDB hadError]) {
			NSLog(@"Err %d: %@", [newDB lastErrorCode], [newDB lastErrorMessage]);
		}
		
		while ([rs next]) {
                    NSLog(@"%@", [rs stringForColumn:@"Name"]);
		}
		[rs close];
	
	[newDB close];

The above code works perfectly fine, when called from anywhere..

However, If I actually Synthesize the FMDatabase in appDidFinishLaunching, and utilise that database for various other uses, it fails.

in AppDelegate.h

 FMDatabase *DB;

@property(nonatomic, retain) FMDatabase *DB;

in AppDelegate.m

@synthesize DB;
-(void)applicationDidFinishLaunching{
	NSString *path = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"database.sqlite"];
   DB = [FMDatabase databaseWithPath:path];
   if (![DB open]) {
    NSLog(@"cannot open db");
   }

}

-(void)doSomethingWithDb{
      FMResultSet *rs = [DB executeQuery:@"select * from tap where id=?",  @"2"];
		if ([newDB hadError]) {
			NSLog(@"Err %d: %@", [DB lastErrorCode], [DB lastErrorMessage]);
		}
		
		while ([rs next]) {
                    NSLog(@"%@", [rs stringForColumn:@"Name"]);
		}
		[rs close];
}

I thought atleast, theoretically this would work, but it didnt.
When i called -doSomethingWithDb at runtime, i got the error:

objc_msgSend

and this is the line it highlights,

FMResultSet *rs = [theFileb executeQuery:@"select * from tap where id=?",  @"2"];

theres no mention of what else is wrong, in console.


Whats going wrong here? There arent too many examples of how FMDb is to be created initialised. As I plan to call it from many other viewControllers.

Any suggestion is appreciated.

But the code at the top, where a whole new FMDatabase is initialised everytime during the app works perfectly, but theres a certain lag which is either cuz of the FM wrapper itself, i read somewhere about that, or its because of the database being initialised and opened at every call.

 

[bredell]

You've forgotten to retain the database. The FMDatabase:databaseWithPath: method returns a database object that's autoreleased. That's why it works when you're using the database immediately after opening it, but not at a later time.

 

[mraheel]

Oh man, I dunno how I missed that!..

thanks man,

speaking of FMDB, if anyone used it, Does it have better performance? specially when using the Cache feature, I havent noticed much.