在核心数据中存储上下文属性的最佳方法？

Question

I am using Core Data to store objects. What is the most efficient possibility for me (ie best execution efficiency, least code required, greatest simplicity and greatest compatibility with existing functions/libraries/frameworks) to store different attribute values for each object depending on the context, knowing that the contexts cannot be pre-defined, will be legion and constantly edited by the user?

Example:

An Object is a Person (Potentially =Employer / =Employee)

Each person works for several other persons and has different titles in relation to their work relationships, and their title may change from one year to another (in case this detail matters: each person may also concomitantly employ one or several other persons, which is why a person is an employee but potentially also an employer)

So one attribute of my object would be “Title vs Employer vs Year Ended”

The best I could do with my current knowledge is save all three elements together as a string which would be an attribute value assigned to each object, and constantly parse that string to be able to use it, but this has the following (HUGE) disadvantages:

(1) Unduly Slowed Execution & Increased Energy Use. Using this contextual attribute is at the very core of my prospective App´s core function (so it would literally be used 10-100 times every minute). Having to constantly parse this information to be able to use it adds undue processing that I'd very much like to avoid (2) Undue Coding Overhead. Saving this contextual attribute as a string will unduly make additional coding for me necessary each time I'll use this central information (ie very often). (3) Undue Complexity & Potential Incompatibility. It will also add undue complexity and by departing from the expected practice it will escape the advantages of Core Data.

What would be the most efficient way to achieve my intended purpose without the aforementioned disadvantages?

Answer 1

Taking your example, one option is to create an Employment entity, with attributes for the title and yearEnded and two (to-one) relationships to Person . One relationship represents the employer and the other represents the employee .

The inverse relationships are in both cases to-many. One represents the employments where the Person is the employee (so you might name it employmentsTaken ) and the other relationship represents the employments where the Person is the Employer (so you might name it employmentsGiven ).

Generalising, this is the solution recommended by Apple for many-many relationships which have attributes (see "Modelling a relationship based on its semantics" in their documentation ).

Whether that will address all of the concerns listed in your question, I leave to your experimentation: if things are changing 10-100 times a minute, the overhead of fetch requests and creating/updating/deleting the intermediate ( Employment ) entity might be worse than your string representation.