Core Data manages all the grubby details of data persistence and abstracts away the actual data layer (whether it's SQL and its object-relational impedance mismatch baggage or XML and the joy of serialization/de-serialization/rinse/repeat) for you. Actually, it does much more than that, such as handling undo/redo.
One area that I've been finding Core Data somewhat lacking is in the tools support in XCode for code generation. You can generate code using the Design → Data Model → Copy… Method Declarations/Implementations to Clipboard options but it's a convoluted and manual process. This is an all-the-more interesting oversight because the Core Data modeling tool in XCode is otherwise rather excellent.
mogenerator to the rescue!
To address this niche, Jonathan 'Wolf' Rentzsch has a free command-line tool called mogenerator. You can read Jon's motivations for building the tool, but don't follow the project links in that post as they're 404. You can also read about Jon's updates to the app in versions 1.2 and 1.5.
The latest release build, according to the project's SourceForge download page appears to be version 1.6.1 (157KB, .DMG).
An error with XCode 3.1.x
In the version of XCode that I'm running (don't you love how NDAs make you sound cryptic and mysterious? No, I didn't think so!), running mogenerator resulted in the following error:
sh: /Developer/Library/Xcode/Plug-ins/XDCoreDataModel.xdplugin/Contents/Resources/momc: No such file or directory /Users/wolf/code/sf/redshed/cocoa/mogenerator/mogenerator.m:259: failed assertion `model'
It appears that since the last release build of mogenerator, the location of the momc app has changed. It's easy enough to fix this with a symbolic link so I didn't resort to compiling the latest from trunk which may or may not have the fix for this already implemented (see the new Trac and SVN repositories for the project for the latest updates).
If you'd rather use the release version like I did, the symbolic link you have to create is below (just run the command below in Terminal):
ln -s /Developer/usr/bin/momc /Developer/Library/Xcode/Plug-ins/XDCoreDataModel.xdplugin/Contents/Resources/momc
The simplest way to learn the app is to read the help via mogenerator --help and a simple example of its syntax is below:
mogenerator -m MyAwesomeApp.xcdatamodel -O Classes
That will generate four files for each Entity in your data model in the specified Classes folder. If, for example, you have an entity called User, it will create _User.h and _User.m, which hold the generated code (that you shouldn't edit yourself) and files for a _User subclass called User.h and User.m that you can use to implement your custom logic.
The Using mogenerator — Code generation for Core Data — in Xcode 3.1 article by Aral Balkan, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial 2.0 UK: England License.
Hello Aral !
We write May 2009 a.d. and I am already more than chock full of approaches to (web) app dev … But nevertheless Your Xcode/Core Data/mogenerator approach is new to me … I have the impression that this approach is MAC-based only; is that correct ? If yes, it is no wonder I have not stumbled upon this approach before, because I am exploring the approaches in the WINDOWS world. What I like about Core Data at first glance is its baked-in Undo/Redo Management :-) ! So yes: Can one use this Xcode/Core Data/mogenerator approach to build RUEs (Rich User Experiences) of all kinds ? For example to build browser-based RIAs, too ? And could this approach be worth to switch from the WINDOWS world to the MAC world ? Or asked the other way round: Do You have a recommendation for an approach in the WINDOWS world which resembles the Xcode/Core Data/mogenerator approach ?
Cheers and Tschüss
Kai (Tischler) from Northrhine-Westfalia in Germany
[...] is a very useful utility that creates model classes for you when working with Core Data. I’ve written about Mogenerator before but what I didn’t realize is that I wasn’t working with the latest version (the version I was using [...]
[...] is a very useful utility that creates model classes for you when working with Core Data. I’ve written about Mogenerator before but what I didn’t realize is that I wasn’t working with the latest version (the version [...]
[...] is a very useful utility that creates model classes for you when working with Core Data. I’ve written about Mogenerator before but what I didn’t realize is that I wasn’t working with the latest version (the version [...]
[...] is a very useful utility that creates model classes for you when working with Core Data. I’ve written about Mogenerator before but what I didn’t realize is that I wasn’t working with the latest version (the version [...]
[...] is a very useful utility that creates model classes for you when working with Core Data. I’ve written about Mogenerator before but what I didn’t realize is that I wasn’t working with the latest version (the version [...]
[...] is a great way for automating this process, using mogenerator. The tool can be downloaded as a DMG installer (Aral Balkan’s blog mentions a workaround for older Xcode versions, but for Xcode 3.1.3 it [...]
[...] 1.5 plus trick $ ln -s /Developer/usr/bin/momc [...]