获取NSManagedObject属性验证正则表达式

Question

In my data model, some of the attributes have regular expressions used for data validation. There are places in my code that I would like to use those same regular expressions.

In the interest of keeping my common regular expressions in one place, I was hoping either to set these regexes in code or to retrieve them from the data model in code.

Is there a way to do this?

I want to access the Reg. Ex. property, shown below, in code.

Answer 1

From a NSEntityDescription you can get its attributes with the method attributesByName . Then you can use the NSPropertyDescription methods validationPredicates and setValidationPredicates:withValidationWarnings: . I assume that a predicate is created under the hood when you set the validation regex in your datamodel file...

I am not completely sure about this, but I think you can only set these values when you are creating your core data model, not once you have your core data stack set up. Is that what you want to do?

Answer 2

Absolutely. Everything you do in the model editor can be done or modified in code by manipulating your NSManagedObjectModel object.

Locate where the model is retrieved in your core data stack setup (maybe in your app delegate). Before returning the model, modify it in code, using constants you can #define in a central include file.

Read all about the object model's API here . More precisely, you set the model's entities after modifying an entity description, by changing the validationPredicates of one of its attributes .

Answer 3

I marked e1985's answer as accepted, since that's the answer that led me here. Here's the code I used to get the predicate. It's in a category for NSEntityDescription.

- (NSPredicate*)getValidationPredicateForAttribute:(NSString*)attributeName
{
    NSAttributeDescription* emailAttribute = [self.attributesByName objectForKey:attributeName];
    NSArray* validationPredicates = [emailAttribute validationPredicates];

    if(validationPredicates.count > 0)
    {
        return [validationPredicates objectAtIndex:0];
    }

    return nil;
}