I have unmanaged solution installed in un online prod environnement and I want to install a new version of this solution in the same environnement, my question is that if I do that, what will happen to my data entities as I don't want to lose my data from the environnement?
Thanks in advance,
The data in the base tables will be not be altered when importing a new solution.
It will be the entity definition.
If a new attribute has been created for an entity which is set to Business Required then a null value will be held until a user opens the form which will require that value to be supplied before the record can be updated.
+1 to Stefan's answer. I will also add that unmanaged solutions will never delete any data. It is always additive, so if you remove an attribute from an entity in your solution in dev, it will not be removed when you import it into another environment. You'll need to manually track these removals and remove them post solution deployment.
Related
I am trying out JHipster (version 6.4.1) using a Monolith and disk-based H2 database. I have created some entities in JDL and have the basic CRUD webpages working. Now that I feel comfortable with the process, I want to add fields and rename others. I figured I could simply update the JDL, re-import the JDL, start the application, and see the result of my changes. What I see is ValidationFailedException from Liquibase and the application throwing HTTP 500 errors due to database problems.
I have looked all over for guidance on the proper process for handling this seemingly common development scenario. Most of the places I have looked for guidance (such as https://www.jhipster.tech/creating-an-entity) discuss importing JDL as a one-time-only operation and do not discuss how to incrementally change and import the JDL.
I have tried a number of suggestions as seen on SO, such as not overwriting the changelogs, doing a liquibase:diff, and adding that to master.xml. This still causes the ValidationFailedException. In the master.xml I see the comment <!-- jhipster-needle-liquibase-add-changelog - JHipster will add liquibase changelogs here --> which leads me to believe that JHipster should be doing the heavy lifting, but I am just missing a step.
I am by no means a JHipster nor a Liquibase expert, but I want to learn. How I can perform simple entity updates without a huge hassle?
[Update with more detail]
After re-importing the updated JDL, I have managed to get rid of the DB Validation Errors by blowing away the database with rm -rf target/h2db/db.
I'm happy with my changes and feel like a commit is in order. What I see is
master.xml is unchanged
the changelog from the first JDL import has been modified to include the updates I made
If I understand how liquibase works, I would have expected
None of the existing changelogs would be touched
A brand new changelog file would be created that contained just the JDL changes I made this round
master.xml to have changed only in that it would contain an additional changelog entry, pointing to the file created in item 2
Am I misinterpreting how Liquibase represents evolution of the DB schema?
It appears that the page you referenced does have some instructions for updating entities. Farther down the page I saw this:
Updating an existing entity
The entity configuration is saved in a
specific .json file, in the .jhipster directory. So if you run the
sub-generator again, using an existing entity name, you can update or
regenerate the entity.
When you run the entity sub-generator for an existing entity, you will
be asked a question ‘Do you want to update the entity? This will
replace the existing files for this entity, all your custom code will
be overwritten’ with following options:
Yes, re generate the entity - This will just regenerate your entity.
Tip: This can be forced by passing a --regenerate flag when running
the sub-generator
Yes, add more fields and relationships - This will
give you questions to add more fields and relationships
Yes, remove fields and relationships - This will give you questions to remove
existing fields and relationships from the entity
No, exit - This will exit the sub-generator without changing anything
You might want to
update your entity for the following reasons:
You want to add/remove fields and relationships to an existing entity
You want to reset your entity code to its original state
You have updated JHipster, and would like to have your entity generated with
the new templates
You have modified the .json configuration file (the
format is quite close to the questions asked by the generator, so it’s
not very complicated), so you can have a new version of your entity
You have copy/pasted the .json file, and want a new entity that is
very close to the copied entity
I want to store information in some activities that are modified versions of activities imported from an existing database (ecoinvent).
I know we can add fields to activities created from scratch (example). (I guess this is because the structure of the database has not yet been defined...) but is there a way of adding it to activities of an already defined database without breaking it?
The way around I found is to add entries to the author dict, which I can easily access later on. e.g.
act['author']['scenario']='myscenario'
but I admit it is not a very elegant solution.
You can just add whatever data you want. Brightway is a (semi-)schemaless database for exactly this reason.
act['foo'] = 'bar'
act.save()
I am trying to implement iCloud sync in my Core Data app. I am not that pro in programming and this is really an advanced topic I learned... I found that Core Data sync Framework "Ensembles" by Drew McCormack. It seems to make iCloud Sync much easier.
I integrated it in my App and syncing does work quite well as long as I add new objects to my Core Data model. But when I delete an object, it creates duplicates. And then duplicates from duplicates. I ended up having the same Entry (object) like 3-4 times...
Why is that? What am I doing wrong? I did some research and my guess is that global identifiers could solve this?
What are global identifiers? My guess is that they help to avoid duplicates!? But how do I set this? I really have no idea, did a lot of research but couldn´t find an answer to that.
Thanks for help!
Update:
Thanks for help! I read the readme and the book, but since i am beginner not everything is clear to me.
I think I understand the use of global identifiers in Ensembles now, but I don´t know if I´m doing it correctly.
If I understand it right, I have to assign an identifier to each object. I can do this by storing it in an attribute. This identifier can be anything as long as it is unique and a NSString?
In my app the user can store different things, let´s say name, text, title, date and so on. The app is based on the Master-Detail-View template in Xcode and uses Core Data. My Core Data model has only a single entity with some attributes, most are strings and a NSDate. No relationships or anything. If the user hits "+" a new object is created and I store the things the user enters in the attributes.
What I did to add global identifiers is to add a new attribute that stores it.
So when a new object is created i do
/// I did find that to use as identifier !?
NSString *taskUniqueStringKey = newManagedObject.objectID.URIRepresentation.absoluteString;
/// and store it in the attribute.
[newManagedObject setValue:taskUniqueStringKey forKey:#"coreDataObjectID"];
Then i use this:
- (NSArray *)persistentStoreEnsemble:(CDEPersistentStoreEnsemble *)ensemble globalIdentifiersForManagedObjects:(NSArray *)objects
{
return [objects valueForKeyPath:#"coreDataObjectID"];;
}
This seems to work for me. But am I doing it right? Is this the right place to assign a global identifier? I have no awakeFromInsert !?
If this is working, I got the next problem. My app is already live and older entries that the user saved before the update will be missing the global identifier. What can I do about that? I thought what I already got and what is unique and the only thing I can think of is an attribute that saves [NSDate date] when the object is created.
I was trying to use this but I failed because Ensembles will only accept NSString and not NSDate!? Can I use this date attribute, is this unique enough and working as gloabl identifier? And if yes, could you please give me code example in how to convert this from date to string?
Syncing with Ensembles works quite good. No duplicates anymore, you can just switch off iCloud and the entries stay and switch it on again and it syncs like it should without loosing locally stored objects or so. Ensembles is really cool! I am seeing some minor strange behaviors like sometimes sync takes long, sometimes it´s really quick and if I edit things in a short time period on two different devices it gets a bit messed up like an object that I just deleted reappears. But I guess that´s normal? If I take some time between using the app on the different devices everything works fine.
Do I understand it right, there is only that one method to call for sync:
- (void)syncWithCompletion:(void(^)(void))completion
{
if (self.ensemble.isMerging) return;
if (!self.ensemble.isLeeched) {
[self.ensemble leechPersistentStoreWithCompletion:^(NSError *error) {
if (error) NSLog(#"Error in leech: %#", error);
if (completion) completion();
}];
}
else {
[self.ensemble mergeWithCompletion:^(NSError *error) {
if (completion) completion();
}];
}
and you just call it if needed? There is nothing else like doing merge without leeching before, or a method like "this is the actual status - save it like it is now" ?
There are different points in the app where you want to sync. On app start and when terminating will be a good point. In my app there are two points where I should sync I guess: when adding an object and save it to Core Data and when I save changes to the object. I could also provide a button like "sync now". Is this a good approach and do I always just call
[self syncWithCompletion:NULL];
Another question that came up. Can I exclude objects from sync with Ensembles? My app loads tutorial entries as objects once on first app start. I don´t want to sync them if that´s possible somehow?
Thanks a lot for your help! If I could help you with anything like localizing in german or so let me know ! ;)
Yes, this is almost certainly due to not setting up global identifiers for your objects, or at least not doing it properly.
When you leech your ensemble, the local persistent store is imported into the sync data. Without global identifiers, Ensembles will assign random ids to your objects, so it can track them across devices.
Duplicates arise when you leech a second device that has the same data. Ensembles has no way to know that the data represents the same logical objects as on the other device, so it again assigns random ids. Effectively, it treats the objects on each device as being completely independent, so that all end up in your data set after syncing.
The solution is global identifiers. By implementing a CDEPersistentStoreEnsemble delegate method, you can provide Ensembles with global ids, which it can use to identify which objects on different devices belong together.
What should you use for global ids? Often, just a UUID, though for singleton like objects you will just want to pick an id.
You can initialize them in awakeFromInsert. You can store the global ids in attributes on your entities. (Note that if you are migrating an existing app, you will want to check with a fetch if the global ids have been generated BEFORE you try to leech the store for syncing.)
More details are in the README on GitHub and in the book at leanpub.
Update
To answer your update questions:
Yes, an identifier just has to be a string, and immutable. It should not change once assigned.
The NSManagedObjectID is not a very good global identifier, in that it will be different on different devices. We really want something that is global across devices.
If you are starting from scratch, using NSUUID is a good approach. Just create a unique id, and store it in the object.
If you have an existing app, and it has been syncing via another mechanism, you need to come up with a way to provide the same global identifiers on each device. One way to do that is mash up the object properties in some way. Usually that will give you a pretty-close-to-unique value, and it will be good enough for the transition.
As an example, you do a quick fetch, and discover that your objects don't yet have global ids. You go through the objects, and set the global ids to a string comprised of creationDate + text. (You could even shorten this by taking a hash, but it probably isn't that important.) After this initial 'migration' to global identifiers, you would just use UUIDs for any newly created objects.
Note that you don't have to use awakeFromInsert. That is simply a convenient place to put it. As long as you assign the global identifier before saving the object you should be fine.
The easiest way to get a string from an NSDate is to call the description method, but another way would be to get a double using timeIntervalSince1970, and turning that into a string. (Be careful with dates as unique identifiers on their own: often objects created together will have the same creation date.)
You are correct about how you should do a sync: you can simply call syncWithCompletion:.
To answer the question about excluding objects: You can't exclude individual objects, mainly because it could become tricky when those objects have relationships to synced objects. You can handle these objects in one of two ways:
Put them in a separate persistent store, and add that store to the same persistent store coordinator.
Sync the objects, but give them global ids manually, so that the objects are treated the same on each device. Eg. You could just give global ids as 'Sample1', 'Sample2', etc.
To integrate Drew's answer, I guess the two steps are the following.
1 Implement CDEPersistentStoreEnsemble delegate method (see README)
- (NSArray *)persistentStoreEnsemble:(CDEPersistentStoreEnsemble *)ensemble
globalIdentifiersForManagedObjects:(NSArray *)objects {
return [objects valueForKeyPath:#"yourUniqueIdentifier"];
}
2 Generate the unique identifier for a NSManagedObject subclass
- (void)awakeFromInsert {
[super awakeFromInsert];
if (!self.yourUniqueIdentifier) {
self.yourUniqueIdentifier = [[NSUUID UUID] UUIDString];
}
}
In awakeFromInsert you can initialize special default property values, like for example an identifier.
The check is necessary, for example, when you have parent-child contexts. Otherwise you are overwriting the identifier previously set. See Why is awakeFromInsert called twice?.
I'm developing an ASP.NET MVC 4.5 project using EF 6 Code First to an Existing Database. I would like to create some new tables with foreign key relationships to one of the tables in the dbcontext I've created. I've altered and added columns in that original table, creating several migrations. There is real data in that table.
I would prefer to create the new tables in the database, but don't see how EF would generate a model for me. I can code the model myself, but don't see any documentation about how I would add it to the context class generated by EF. And then the migrations would be out of whack.
So I'm thinking that the best thing to do would be to delete all the migrations, delete the context class and drop the migrations table. Then I could start from scratch with an initial migration. Am I missing some gotcha? Is there a better way?
FWIW to others facing this dilemma, I figured it out. First I got rid of all the migrations, following the 100+ up-voted answer here: Reset Entity-Framework Migrations
Second, I created new the tables and constraints I needed in the database.
Third, I created a new entity in my solution and generated model classes from the database. I changed calls from the old entity to the new entity.The generator overwrote the model for the original table, but since I have all the annotations in version control, it is trivial to paste them in.
If I need to, I can enable migrations again.
Hope this helps.
I have an iPad app, built with XCode 4.5, Storyboard, Core Data (using MagicalRecord) and iOS 6. I have two Entities, each with multiple attributes. The first entity has a one to many relationship with the second entity.
In the MagicalRecord docs, I don't see how to persist the data to the second entity; I read somewhere that Core Data generates it's own key and indexes. I know from past use of SQLite that I would need to set the key from the first entity to be able to access the second entity.
[UPDATED] Here is the modified code but it doesn't work either. I have previously selected a row in didSelectRowAtIndexedPath in another class. I assume that set the localContext. Any ideas why this is not working?
- (IBAction)saveAppointment:(UIButton *)sender {
AppointmentInfo *newAppointment = [AppointmentInfo MR_createInContext:localContext]; // create the entity
newAppointment.aStartTime = selectedStartDate;
newAppointment.aEndTime= selectedEndDate;
[localContext MR_saveNestedContexts];
}
You need to create your Entity in the proper (ie. localContext) context:
[AppointmentInfo MR_createInContext:localContext];
I found the problem... seems that I had the store setup incorrectly... I removed the parent pointer from AppointmentInfo and added the "class" information. Works like a champ now... thank you for your time, tho'.