I made a bad decision as I was designing a MongoDB database to embed a model rather than reference it in an associated model. Now I need to make the embedded model a referenced model, but there is already a healthy amount of data in the database (or document?).
I'm using Mongoid, so I reasoned I can just change embedded_in to referenced_in. Before I start, I figured I'd ask people who know better than I do. How can I transition the embedded data already in the database to the document for the associated model.
class Building
embeds_many :landlords
..
end
class Landlord
embedded_in :building
...
end
Short answer - Incrementally.
Create a copy of Landlord, name it Landlord2.
Make it referenced in Building.
Copy all data from Landlord to Landlord2.
Delete Landlord.
Rename Landlord2 to Landlord.
Users should not be able to CRUD Landlord during steps 3-5 (ideally). You still can get away with only locking CRUD on 4-5. Just make sure you make all updates that happened during copying, before removing Landlords.
Just chan ging the model like you have above will not work, the old data will still be in a different strucutre in the db.
Very similar the previous answer, one of the things I have done to do this migration before is to do it dynamically, while the system is running and being used by the users.
I had the data layer separated from the logic, so it let me add some preprocessors and inject code to do the following.
Lets say we start with the old datamodel, then release new code that does the following:
On every access to the document, you would have to check whether the embedded property exists, if it does, create a new entry associated as a reference and save to the database and delete the embedded property from the documents. Once this is done for a couple of days, a lot of my data got migrated and then I just had to run a similar script for everything that was not touched, made the job of migrating the data much easier and simpler and I did not have to run long running scripts or get the system offline to perform the conversion.
You may not ha ve that requirement, so Pick accordingly.
Related
I have a cloudant database with a lot of deleted docs. Since they can't be destroyed, I would like to make a filtered copy with the non deleted items to a temporary base, destroy the original one, and copy the temporary base to a fresh database with the same name as before.
The problem is when I destroy the base, the API keys generated are also destroyed...
So the front app calling the new base can't acces it !
I would like to manually create a user/password, so I can recreate the same user each time I destroy the database.
I don't know how to do it ?
Or is there another way to achieve my goal ??
To answer your actual question, you can't add "users" to a Cloudant account, only databases. You can, however, make API-keys that span multiple databases, which sounds like it could be what you want:
https://dx13.co.uk/articles/2016/04/11/using-a-cloudant-api-key-with-multiple-cloudant-databases-and-accounts/
But as was noted by bessbd above, if your data model relies on document deletion, you're working against the grain of Cloudant, and sooner or later you'll end up with problems.
And finally -- the doc links appear to work just fine.
Maybe some useful stuff here: https://blog.cloudant.com/2019/11/21/Best-and-Worst-Practices.html
[disclaimer, I wrote that]
Can you please expand a little further on your use case? Why do you want to get rid of the deleted docs? Is there a way to avoid deleting the docs? Also, have you already read https://cloud.ibm.com/docs/services/Cloudant?topic=cloudant-documents#tombstone-documents ?
I have some processes that ran with old process definitions. But due to requirement change the user task data has been updated with new attributes and this process definition has been deployed. I'm aware that "SetProcessDefinitionVersionCmd" can be set to "yes" to point the processes to the new definition/version.
I would like to know how to migrate the old process data to have the newly added attributes of the user task updated in them?
There is no easy way to migrate process instance data, however, when you set the version to the new process definition the instance data will go with the migrated instance.
What you have to be careful of is to make sure you include null checks for any of the data that may not be present in the migrated process instances.
Hope this helps,
Greg
Indeed there is no easy way for migration, however depending on the differences between the two definitions and to what extend you may not prefer to use SetProcessDefinitionVersionCmd, you may find DynamicBpmnService useful when combined with detecting definitions' versions inside your logic.
And yes another way would be to use SetProcessDefinitionVersionCmd but be extra cautions for tasks that were actually active prior to migration, as Activiti's database model have some redundant data (some for performance reasons), you are better studying the DB tables first for these tasks and then inspecting the before and after migration state. For example, keeping up with a simple changed attribute is much easier than an added boundary event on an active User Task, which affects the "execution tree".
I would also advice to compare SetProcessDefinitionVersionCmd's implementations between Activiti and Camunda, it is sad to have such enhancements efforts separated, but that is another story.
So this is a question about Serialization and Versioning. I have a program that is a Music database that stores sheet music with Name, Composer, ...
I serialize each song to a hidden folder so that the user can reload the database at next launch.
Now, when I have to change something in the Song class all is fine if it is a compatible change. I had the idea that if I were to make an incompatible change, would I be able to create a second class with the same name 'Song' but a different VersionUID. Then when it reads the Songs, if the saved version doesn't match the latest version, it will go to a method that will read the Song into the old UID then go through a series of steps to convert it to the new Version. Is any of this possible?
I do know that you can have multiple methods with the same name but different parameters. Would this work with classes and VersionUID's or some other variable?
Thanks!
No it would not. Classes do not support a concept like "property overload" so a class with the same name is considered as the same class, even if it has different properties.
The "best" way for you would be a migration to a relational database in combination with EntityFramework6 (there is a SQLite adapter out there, so you don't need SQLServer).
With EF you can use migrations which enables you to change your model and migrate the data automatically. If done correctly you can change the model and no data loss occurs.
i want to generate Model and CRUD automatically when my new table created.
i am creating new table(xyz_uid) dynamically after successful registration of user. and i am inserting some data related to that particular user. this thing is working fine for me.
i creating separate table for each user because for every user table attributes may different and i tried to keep one table instead of making new table for every user but it's smashing everything in my project.
i want to generate Model and CRUD of that user so i can do future transaction with that table.
i know how to generate Gii manually from ?r=gii. but here i want to generate automatically from back end.
i tried to search about this in Yii forum and in google also. but i didn't found anything.
is there any extension or anything which will generate it automatically.
will it be good idea to create model and CRUD for every table? or shall i communicate with table directly using CDbCommand?
you may use giix-core.
While You install the giix-core it's create the model and basemodel so if u have any changes in DB every time u can create the basemodel not a model.
so it's easy working and u can use method override.
Note: Please make sure you can not write any code in BaseModel
for more please refer following link...
http://www.yiiframework.com/forum/index.php/topic/13154-giix-%E2%80%94-gii-extended/
I have the following scenario:
I'm starting development of a long project (around 6 months) and I need to have some information on the database in order to test my features. The problem is that right now, I don't have the forms to insert this information (I will in the future) but I need the information loaded on the DB, what's the best way to handle this? Specially considering that once the app is complete, I won't need this process anymore.
As an example, lets say I have tasks that need to be categorized. I've begun working on the tasks, but I need to have some categories loaded on my db already.
I'm working with Rails 3.1 btw.
Thanks in advance!
Edit
About seeds:I've been told that seeds are not the way to go if your data may vary a bit, since you'd have to delete all information and reinsert it again. Say.. I want to change or add categories, then I'd have to edit the seeds.rb file, do my modifications and then delete and reload all data...., is there another way? Or are seeds the defenitely best way to solve this problem?
So it sounds like you'll possibly be adding, changing, or deleting data along the way that will be intermingled amongst other data. So seeds.rb is out. What you need to use are migrations. That way you can search for and identify the data you want to change through a sequential process, which migrations are exactly designed for. Otherwise I think your best bet is to change the data manually through the rails console.
EDIT: A good example would be as follows.
You're using Capistrano to handle your deployment. You want to add a new Category, Toys, to your system. In a migration file then you would add Category.create(:name => "Toys") or something similar in your migration function (I forget what they call it now in Rails 3.1, I know there's only a single method though), run rake db:migrate locally, test your changes, commit them, then if it's acceptable deploy it using cap:deploy and that will run the new migration against your production database, insert the new category, and make it available for use in the deployed application.
That example aside, it really depends on your workflow. If you think that adding new data via migrations won't hose your application, then go for it. I will say that DHH (David Heinemeier Hansson) is not a fan of it, as he uses it strictly for changing the structure of the database over time. If you didn't know DHH is the creator of Rails.
EDIT 2:
A thought I just had, which would let you skip the notion of using migrations if you weren't comfortable with it. You could 100% rely on your db/seeds.rb file. When you think of "seeds.rb" you think of creating information, but this doesn't necessarily have to be the case. Rather than just blindly creating data, you can check to see if the pertinent data already exists, and if it does then modify and save it, but if it doesn't exist then just create a new record plain and simple.
db/seeds.rb
toys = Category.find_by_name("Toys")
if toys then
toys.name = "More Toys"
toys.save
else
Category.create(:name => "More Toys")
end
Run rake db:seeds and that code will run. You just need to consistently update the seeds.rb file every time you change your data, so that 1) it's searching for the right data value and 2) it's updating the correct attributes.
In the end there's no right or wrong way to do this, it's just whatever works for you and your workflow.
The place to load development data is db/seeds.rb. Since you can write arbitrary Ruby code there, you can even load your dev data from external files, for instance.
there is a file called db/seeds.rb
you can instantiate records using it
user1=User.create(:email=>"user#test.com",
:first_name=>"user",
:last_name=>"name",
:bio=>"User bio...",
:website=>"http://www.website.com",
:occupation=>"WebDeveloper",
:password=>"changeme",
:password_confirmation=>"changeme",
:avatar => File.open(File.join(Rails.root, '/app/assets/images/profiles/image.png'))
)
user2=User.create(:email=>"user2#test.com",
:first_name=>"user2",
:last_name=>"name2",
:bio=>"User2 bio...",
:website=>"http://www.website.com",
:occupation=>"WebDeveloper",
:password=>"changeme",
:password_confirmation=>"changeme",
:avatar => File.open(File.join(Rails.root, '/app/assets/images/profiles/image.png'))
)
Just run rake db:seed from command line to get it into the db