So I am looking for a better way to fetch all entities from each month
of the year so that I can get a total for each month.
Each entity has a date, amount, & type (which is a to one
relationship to a type entity, the reverse is to-many). In the end I
want to break things down so that the app can tell you "Jan type A =
$300, type B = $100, ..."
I have a method that currently tells me how many entities are from
each month of the year and can easily then add the amounts. The
problem is that I have 8 pages of code so far and I haven't actually
added up the totals or split them be type. I am looking to see if
anyone has any ideas to make this be less code and therefore more
efficient. Below are the tedious steps I have to go through:
Get the correct NSEntityDescription
Create the basic strings for beginning and end of the month
NSString *greaterPredString = [NSString stringWithFormat:@"%@ >= %
%@", @"date"];
NSString *lessPredString = [NSString stringWithFormat:@"%@ < %%@",
@"date"];
Create an NSMutableArray and put 12 NSDateComponents into it.
Get the current date.
Create an NSCalendar (NSGregorianCalendar)
Extract the year form the current date.
Enumerate through the NSDateComponents array setting each
NSDateComponents to the current year, day 1, month i, hour 0. minute
0, second 0.
Create one last NSDateComponents for the first day of the next year.
Create an NSDate from each of the NSDateComponents and put them in an
NSMutableArray.
Create two predicates for each month:
NSPredicate *janStartPred = [NSPredicate
predicateWithFormat:greaterPredString, jan];
NSPredicate *janEndPred = [NSPredicate
predicateWithFormat:lessPredString, feb];
Create NSCompoundPredicate () for each month with the start and end
predicates:
NSPredicate *janPred = [NSCompoundPredicate
andPredicateWithSubpredicates:[NSArray arrayWithObjects: janStartPred,
janEndPred, nil]];
Create an NSFetchRequest for each month. Setting the entity and
predicate.
Create an NSError to go with each NSFetchRequest.
Create an NSArray to go with each NSFetchRequest and fill it with the
fetch results: NSArray *janArray = [[self managedObjectContext]
executeFetchRequest:janReq error:&janError];
Check to see if there were any results from the fetch.
Enumerate through the != nil arrays, retrieve the amount attribute of
each entity and add them together.
This of course does not separate entities for a given month by type to
be summed that way.
I am still relatively inexperienced and am certain that I am just
missing the easy way to do this. Any ideas are appreciated.
Thank You,
Mike Swan
http://www.michaelsswan.com
"As human beings our greatness lies not so much in being able to
remake the world... as being able to remake ourselves" - Gandhi
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