So I'm using Core Data in an existing iPhone app, and I've set up two entities: Person and Item. The root view of my app's navigation (currently) shows a list of people, and you drill down from there to items. In short, the hierarchy looks like this:
Person -> Item
I want to add a new entity above Person in the hierarchy, called List:
List -> Person -> Item
Additionally, I want the user's first List to be created for them on startup, and for any People the user's already added to be assigned to that list.
I'm familiar with Core Data's lightweight migration & versioning feature, so I think I know how to add the new entity and relationship, but I'm not sure how to:
Create a List record on app start if they've never had the Lists feature before
Set all existing People records to belong to that new list.
One quick and dirty way would be to add some code to my app delegate's applicationDidFinishLaunching method that performs the migration by (1) checking to see if there are any Lists, (2) if not, creating the default one, (3) fetching all existing People from my data store, (4) setting each Person's list attribute to the newly created default list, and finally (5) saving those changes.
My question is: is there any faster or easier way to do all of that?
That's pretty much what you'd want to do. Use an NSFetchRequest to see if any Listss exist. If not, create one. Then do another request to get all the Persons. Here, instead of assigning the list property of each Person, I'd create an NSSet containing all your Persons and assign that to the List's people property. You did create an inverse property, right?
This is actually a pretty lightweight operation, all tolled, so I wouldn't worry too much about performance. Unless you've got hundreds or thousands of Person objects, your user will probably won't even notice.
Related
I'm using the WorkFront / AtTask API and when looking up Tasks, I'd like to filter them down to the Projects that contain specific Roles.
using /TASK/search/?fields=project:roles it will show me the Roles, but then I'm not sure how to filter on those.
Accessing a tertiary object directly (fails)
I tried /TASK/search/?project:roles:ID=aaaaaaa but the API returns (422) Unprocessable Entity.
Access from the parent object (works)
task -> project -> /PROJ/search/?roles:ID=aaaaaaa works, but involves sub-queries to the API that are costly and slow.
Access from secondary object's ID fields (works)
/TASK/search/?project:ownerID=bbbbbbb since it references a field of a secondary object and not yet another object. But I've only been able to make this work with single-instance references and don't know how to access the ID fields of collections without referencing them as objects.
So how could I filter or access down to a secondary object's collection? I can view them in a single API query, but can't seem to filter.
Task > It's Project > filter by Role
This functionality is not available in Workfront, neither through the API nor through built-in tools like Reports. This is due to a constraint on the database side of things. After seeing this question I spoke with my enterprise support team at Workfront and received confirmation of this from the DBAs.
The solution that you provided is the best you can do - split this query into the front and back half of your parameters and filter results within your code.
The best solution I can think of thus far is:
Pull the list of acceptable projects based on role.
/PROJ/search/?roles:ID=aaaaaa&...
Save the list of projects in memory
Pull the list of Tasks in question
/TASK/search/?...
Remove the tasks that don't have a project ID from step 2
This way it's only 2 queries and the project query should have a minimal impact in terms of size and number of entries.
(Using Ektron version 8.6.1)
Say I have a smartform ContactInfo, something like:
<ContactInfo>
<Name></Name>
<Email></Email>
</ContactInfo>
I would like to create another smartform (e.g. NewsArticle) and "embed" ContactInfo inside
<NewsArticle>
<Title></Title>
<Summary></Summary>
...
<ContactInfo>
<Name></Name>
<Email></Email>
</ContactInfo>
</NewsArticle>
My solution thus far has been to include a Resource Selector field to add a reference to an existing smartform instance. I would prefer to make the association at the configuration level, to make the data entry workflow more intuitive.
I'm using Bill Cava's ContentTypes and generating classes from smartform XSDs, so it would also make the presentation code more natural and type-safe in that embedded fields could be accessed directly (rather than having to make another request based on a reference ID, which may or may not be an ID to the smartform I'm expecting).
I gather this is not possible out of the box; I'm not opposed to hacking Workarea code to make something like this work. Does anyone have experience with a scenario like this?
I heard from an Ektron rep that they are planning on elevating the role of smartforms in an upcoming summer release - can anyone offer some more info to that point? Perhaps smartform composition like I've described will be supported?
Currently it isn't possible to do smartform composition. Depending on why/if you actually need a second smartform definition, you could just define the contact info in the news article.
If the contact info smartforms are related to the news articles in a one to many or many to many fashion, then using the resource selector as you have is the only way that I know of to create the relationship you are looking for.
If the relationship is one-to-one or many-to-one, then I'd suggest doing away with the separate smartform definition.
If you can clarify the workflow you are trying to achieve for the content authors, I might be able to respond better.
The Content Types would represent the data in the CMS. Suppose, as in your example, a NewsArticle contains a reference to a ContactInfo. Embedding the ContactInfo inside your NewsArticle might make sense from a presentation perspective, but it turns your ContentTypes into a one-way data model. You would lose the ability to construct a new NewsArticle and persist it into the CMS.
What might work well for you is to leave the content types as-is, with the id of the ContactInfo from the resource selector. Then create a NewsArticleDisplayModel... essentially a view model that contains the news article data plus ContactName and ContactEmail.
Now, if you need the contact info to be searchable, you could get really fancy with CMS Extensions and hook into the OnBeforePublish event to update searchable metadata with the name from the ContactInfo, so that the NewsArticle can be searched for using the values from the other "embedded" resource. That could get kinda tricky, though... ideally you'd have to also hook into the publish events of the ContactInfo objects in case something changes on that side, too. Then do you create a custom database table to track which NewsArticle content ids are using a particular ContactInfo?
Your solution can get as complex as it needs to, but I would keep the content blocks separate. If nothing else, you'll end up with a more maintainable and upgradable solution.
I have some basic objects like Customer, Portfolio and ... with some association to other objects. I can easily display the required information in the web page by reading object values. The problem is that what do I do when the value associated with the object is calculated and returned by a method, a value that makes sense only in certain context and cannot be attached to the object as an instance variable? In this case if I have a list of say Users I have to pass the username of each user to the method to get the calculated value. This causes problem to keep the association while displaying the values in the page.
An example to make this clear:
An application provides the functionality for users to keep track of each others activities by letting them add whoever they want to a list. If this user performs a search on users there's the option to follow each returned user. I want to make sure this option is disabled for those user's that are already being followed. This functionality is provided by a method like isFollowed(String follower, String followee) which returnes a boolean. How can I associate this boolean values to each user in search result?
Solutions:
One thing I can think of is to add a followed instance variable to User class. But I don't think it's a good approach because this variable only makes sense in a certain context. It's not a part of User class in the domain.
The other way I can think of is to use Decoration or Wrappers in a way to extend the User class and add the attribute in the child class. But again what if I have several objects that need to be in the same context. In that case I have to extend all of them with the same boolean attribute in all classes.
I hope I could make it clear.
In principle, I don't see anything wrong with instance method on User: bool IsFollowedBy(User user).
Of course, this could lead to performance issues. If that is the case, you can create separate object for presentation purposes which bundles data from User and whether he is being followed by the user performing search. Then you can build query which retrieves all necessary data for such object in a single roundtrip to DB.
One solution is to avoid querying Entities (as in DDD/ORM) and query directly using subquery/join or even using some denormalized database. This is something CQRS pattern suggests.
Other solution is to do computations on application layer (how many Users can you show on the same page anyway), which is expensive but you can implement some caching techniques to make things easier.
Let's say we have "User" and a "Hotel" model classes. I'd use a User_Mapper and Hotel_Mapper to load/save/delete etc. I want to then have the user be able to mark their "favourite" hotels. In the database I have my user_favourite_hotels table which is a simple link table along with say a field for subscribing to hotel updates.
When listing out the user's favourite hotels, how would you expect this to work from an API point of view? A part of me thinks that this should be a "findFavouritesByUserId" method on the Hotel_Mapper, but other than saying it "feels" right - however a colleague suggests that the "favourites" is owned by the user and should therefore be on the User_Mapper.
Perhaps I should have a User_Hotel_Favourites_Mapper? I was thinking of incorporating the "favourites" data in to the User object so it's saved and loaded whenever the User object is. I'm not sure whether it'd be better to split it out in to it's own object and mapper however.
I'd appreciate any advice on how best to setup the API for the above and any pros/cons/experiences.
Thanks very much,
James.
This (admittedly retired) patterns&practices guide to designing data tier components suggests that you put the method in the mapper of the type of object that you're getting back from the call.
If you have methods that return a particular type of business entity, place these methods in the Data Access Logic Component for that type. For example, if you are retrieving all orders for a customer, implement that function in the Order Data Access Logic Component because your return value is of the type Order. Conversely, if you are retrieving all customers that have ordered a specific product, implement that function in the Customer Data Access Logic Component.
So, in your example, it would go in the Hotel Mapper as it is returning Hotels.
If you want to store favorite hotels for the user, you are using the UserMapper, which notices that domain object for User has changes favorites, and updates both tables for users and for user_favorite_hotels ( you just need the hotel IDs ).
When you are retrieving favorite hotels of some user, you use HotelMapper and set filter to be based on User, because you will be working with instances of Hotel.
Considering that this was asked more than 2 years ago, I'm not sure if an answer matters to you now. But here's what I think anyway.
If User could have multiple types of favourites (including Hotels), it may make sense to have a UserFavourites abstraction to cover all possible types of favourites. UserFavourites could expose a getItems() method to get the underlying Favourites.
This could be managed with the help of a manager class to return the appropriate Favourites object(FavouriteHotels for example) on which the getItems() method can be called.
I was wondering how you actually remove objects from the Calendar Store, I've looked at the documentation and it only mentions how to add objects but nothing about removing.
How would I remove an object from the calendar store?
How would I remove an object from the calender store?
Buy out their stock!
Serious answer: The CalCalendarStore object responds to two messages that remove a calendar item: one for events, the other for tasks. Use whichever one is appropriate to the item you want to remove.
As Peter points out in his comment; it isn't enough to identify a CalTask just by it's title.
So, how do you uniquely identify a task?
If you look at the documentation for CalTask you will see that it is a sub-class. The super-class has a property which you can use to uniquely identify objects of that super-class, and because CalTask is a sub-class, it too has that property.
Have a look at the code that you used to create those tasks in iCal. When you create each task you can inspect its properties for that property and store it in your model. Then, when you come to delete the tasks from iCal, you can use that property to uniquely identify the task that is to be deleted.
I make no apologies for not being more specific in this answer. You'll need to read the documentation and try and write this for yourself. You'll need to make changes in more than one place in your app:
Change the model so that you can store this unique identifier for the tasks you create.
Change the method that you use to create and add task to the Calendar Store so that you get this identifier and store it in your model.
Make use of this identifier when you are trying to identify the tasks in the Calendar store that you want to delete.