Fetching data with relationship in core data

Question

I am using core data framework and want to fetch the data using relationship. I have 2 entities named User and Company having user_name and company_name field's. I also have relationship to-many name rel_user->user.

Now I am trying to fetch data like this

User *userObj=(User*)[selectedData objectAtIndex:indexPath.row];
NSSet *resultData = [userObj valueForKeyPath:@"rel_user.user"];
    NSLog(@"subject -> %@",[resultData description]);

I want to show the company name related to user.

jrturton · Accepted Answer · 2013-11-25 07:18:15Z

1

What is the name of the inverse relationship to rel_user? Assuming it's rel_company and the user -> company relation is to-one, you'd just use

user.rel_company.company.name

Where user is a particular User object.

There isn't really any benefit to specifically naming your relationships rel-something. It reads much nicer to have a company relationship on the User (since it will be a property holding the Company) and a users relationship on the Company. You can then tell from the name what the property will contain and if it is a to-one or to-many relationship.

answered Nov 25, 2013 at 7:18

jrturton

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2 Comments

RJ168 Over a year ago

Hello Thank you for replying but I can't find the relationship property with the User object. How can I get that do I need to set parent class for that??

jrturton Over a year ago

You define the relationships yourself in the core data model editor. If you don't create subclasses, you'll have to use valueForKeyPath.

user2068378 · Accepted Answer · 2013-11-25 10:43:46Z

0

you can fetch related company name by relation name.

User userObj=(User)[selectedData objectAtIndex:indexPath.row];

NSString *companyName = userObj.RELATION_NAME.company_name

RELATION_NAME is used to connect from user entity to company entity.

Hope this will help.

answered Nov 25, 2013 at 10:43

user2068378

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