NSPersistentDocument provides way to configure store options on initial Save or on Save As

Number:rdar://19806400 Date Originated:11-Feb-2015 07:39 PM
Status:Open Resolved:
Product:OS X Product Version:Mac OS X 10.10.2 (14C109)
Classification:Enhancement Reproducible:Always
While NSPersistentDocument has the method 
- configurePersistentStoreCoordinatorForURL:ofType:modelConfiguration:storeOptions:error: it is only called when opening an existing persistent store. But it’s not used when saving a new document or during Save As. These are handled automatically by the class. The problem is that it’s not possible to set options for the store. 

Specifically, it makes a lot of sense for the SQLite stores to have the journal_mode = DELETE pragma set to avoid creating 3 files (WAL, SHM). Having 3 files for a document is a no-no! 

Steps to Reproduce:
In an application that uses NSPersistentDocument:

configurePersistentStoreCoordinatorForURL:ofType:modelConfiguration:storeOptions:error: and add to options: 
options[NSSQLitePragmasOption] = @{ @"journal_mode" : @"DELETE" };

Run application.
1. Create a new, untitled document.
2. Modify some data
3. Save it

Expected Results:
Save only creates one file for the document.

NSPersistentDocument should either consult the configure method (though it’s only used for opening, supposedly), or create a similar method for modifying options when save occurs. In any case, something is wrong here.

Actual Results:
Creates 3 files: document and two files needed for WAL.


Currently working around this by overriding:
- (BOOL)writeToURL:(NSURL *)absoluteURL ofType:(NSString *)typeName forSaveOperation:(NSSaveOperationType)saveOperation originalContentsURL:(NSURL *)absoluteOriginalContentsURL error:(NSError **)error {

    // Handle first saving and Saving As to set the correct options for SQLite because Core Data forgets our pragmas, stupid
    BOOL success;
    if (saveOperation == NSSaveAsOperation) {
        NSMutableDictionary *options = [NSMutableDictionary dictionary];
        options[NSSQLitePragmasOption] = @{ @"journal_mode" : @"DELETE" };
        options[NSMigratePersistentStoresAutomaticallyOption] = @YES;
        options[NSInferMappingModelAutomaticallyOption] = @YES;
        NSPersistentStoreCoordinator *coordinator = [[self managedObjectContext] persistentStoreCoordinator];
        NSPersistentStore *store;
        if (absoluteOriginalContentsURL) {
            store = [coordinator migratePersistentStore:[self persistentStore] toURL:absoluteURL options:[options copy] withType:NSSQLiteStoreType error:error];
            success = (store != nil);
        } else {
            store = [coordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:absoluteURL options:[options copy] error:error];
            success = (store != nil);
            if (success) {
                success = [[self managedObjectContext] save:error];
    } else {
        success = [super writeToURL:absoluteURL ofType:typeName forSaveOperation:saveOperation originalContentsURL:absoluteOriginalContentsURL error:error];
    return success;


I think we are supposed to override managedObjectContext to implement this. When NSPersistentDocument needs the coordinator it gets it goes via this property.

By indiekiduk at Jan. 24, 2023, 6:20 p.m. (reply...)

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