Core data fetch relationship predicate nominative

ios - How to fetch core data relationships in one single NSFetchRequest? - Stack Overflow

Data based on linguistic intuition. .. Extensions from the core: less prototypical qualifying verbs. .. predicative relation between the two postverbal phrases and to explain how the same syntactic formula can convey called XP a "Predicate Adjective or Noun referring to the Object" as early as (41), and. Rich relationships inside graph-like data are the driving force of many For most large enterprises today, data constitutes their core asset, along with code and .. infrastructure to store, retrieve, share, and serve custom metadata for their The constraint can be either an adjective or an entity that is “compatible” with. do { let predicate = NSPredicate(format: "categoryName == %@", " yourCategoryHere") let fetchSubcategory = NSFetchRequest(entityName: " Subcategory").

The major exception is a fetched property, which represents a weak one-way relationship—there is no relationship from the destination to the source.

Core Data Programming Guide: Fetching Objects

See Weak Relationships Fetched Properties. The recommended approach is to model relationships in both directions and specify the inverse relationships appropriately. Core Data uses this information to ensure the consistency of the object graph if a change is made see Manipulating Relationships and Object Graph Integrity. Relationship Delete Rules A relationship's delete rule specifies what should happen if an attempt is made to delete the source object.

Note the phrasing if an attempt is made. If a relationship's delete rule is set to Deny, it is possible that the source object will not be deleted. Consider again a department's employees relationship and the effect of the different delete rules.

Adding Core Data entity relationships: lightweight vs heavyweight migration

Deny If there is at least one object at the relationship destination employeesdo not delete the source object department. For example, if you want to remove a department, you must ensure that all the employees in that department are first transferred elsewhere; otherwise, the department cannot be deleted.

Nullify Remove the relationship between the objects, but do not delete either object. This only makes sense if the department relationship for an employee is optional, or if you ensure that you set a new department for each of the employees before the next save operation.

Cascade Delete the objects at the destination of the relationship when you delete the source.

For example, if you delete a department, fire all the employees in that department at the same time. No Action Do nothing to the object at the destination of the relationship. For example, if you delete a department, leave all the employees as they are, even if they still believe they belong to that department.

It should be clear that the first three of these rules are useful in different circumstances. For any given relationship, it is up to you to choose which is most appropriate, depending on the business logic. It is less obvious why the No Action rule might be of use, because if you use it, it is possible to leave the object graph in an inconsistent state employees having a relationship to a deleted department.

Remember, we made the "name" attribute indexed, which makes it lightning fast for search. If no matching author is found we'll create and configure a new author, and use that instead. Put this new code just before the end of the configure commit: To show that this worked, change your cellForRowAt method so that the detail text label contains the author name as well as the commit date, like this: Now change its viewDidLoad method to this: We haven't written a showAuthorCommits method yet, but don't worry: Now that every commit has an author attached to it, I want to add one last filter to our changeFilter method to show you just how clever NSPredicate is.

Add this just before the "Show all commits" action: Joe is one of Apple's Swift engineers. Although it's fairly likely you'll see commits by him, it can't be guaranteed — I'm pretty sure that Apple give him a couple of days vacation each year.