Hi Paul and everyone,
What you did is ok - not bad but since you are asking for more here you go.
It is probably a bad idea to model the back relationship from “Role -> Users”
as one role could be used by thousands of users. You don’t want to fault all
those people in when you “addToBothSidesOfRelationshipWithKey().” That said you
*could* model it and be careful to not add to both sides and be careful never
to trip that fault. You could also model it as a “non class” invisible
property. If you had this relationship you could do the following.
EOQualifier noticeQualifierForUser =
Notice.ROLES.dot(Role.USERS).containsAnyObjectSatisfying(loggedInUser.identityQualifier())
You can use that one qualifier to fetch all the Notices for your user.
The “identityQualifier()” could be defined in your EO like so:
public EOQualifier identityQualifier() {
final EOEntity entity = entity();
final NSDictionary<String, Object> primaryKeyDictionary =
primaryKeyDictionary(false /* inTransaction */);
final EOQualifier thatAreThis =
entity.qualifierForPrimaryKey(primaryKeyDictionary);
return thatAreThis;
}
Note: “containsAnyObjectSatisfying()” is a thin wrapper of
“ERXExistsQualifier.” If you prefer, you could create that exists qualifier
directly and specify if you want an “in” or exists syntax to be generated.
AARON ROSENZWEIG / Chat 'n Bike
e: [email protected] t: (301) 956-2319
On May 10, 2016, at 6:22 PM, Paul Hoadley <[email protected]> wrote:
> Hello,
>
> I have two entities, User and Notice, each of which has a to-many
> relationship to Role called roles. The business rule here works as follows.
> Say Notice.roles contains two Roles, R1 and R2. If User.roles contains either
> R1 or R2, then the Notice is applicable to that User—that is, Notice.roles
> says that for each Role, the Notice applies to any User that has that Role.
>
> I have a static method on Notice to return an NSArray<Notice> applicable to
> some supplied User. (There are other matching criteria, but this is the part
> I want to try and simplify.) At the moment, I’m doing this:
>
> NSMutableArray<EOQualifier> roleQuals = new
> NSMutableArray<EOQualifier>();
> for (Role r : user.roles()) {
> roleQuals.add(Notice.ROLES.containsObject(r));
> }
> EOQualifier roleQual = ERXQ.or(roleQuals);
>
> While this works, it seems awkward. Is there a way to create this qualifier
> (which is essentially looking for any match between User.roles and
> Notice.roles) in one step?
>
>
> --
> Paul Hoadley
> http://logicsquad.net/
>
>
>
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