4 ms·

What's the alternative to sharing logic across ActiveRecord models?

by Axsuul 6y ago

seancoleman 6y ago
I think a different way of looking at the problem is that ActiveRecord models really shouldn’t have much, if any logic. Instead, logic should get delegated to other types of object, such as services, decorators, query objects, etc. While “fat models” is certainly better than “fat controllers”, I’m afraid it lead the Rails community astray with large-scale apps that required more nuanced architecture.
Fire-Dragon-DoL 6y ago
Don't put the logic in activerecord models at all. Not even the data. Use activerecord uniquely as a querying mechanism (read or write), don't use relationships and don't put validations in there. Create objects (aka behavioral objects, aka servoce objects) for the logic and create entities (plain ruby objects) when you need to pass around the data. Yes, you are essentially eliminating the entirety of activerecord. After 10 years of rails, you realize that is the only safe way to use that library. By the way User User::SignUp Are related. The behavior doesn't need to be in the same object, the namespace takes care of that already.
- swader999 6y ago
  That's a breath of fresh air to read.
- megraf 6y ago
  You're correct on all fronts. Domain driven design, POROs- all of it. I bet you maintain something nice!
  - Fire-Dragon-DoL 6y ago
    Thanks, I really appreciate that. I do my best, but the sad reality is that I made an insanely large amount of mistakes in my development life, I didn't reach these conclusions without doing damage myself. I try to give back by training developers and making sure the business gain awareness so they don't have to experience the complete halt of feature development when the software becomes unsuited for changes.
- e12e 6y ago
  > Use activerecord uniquely as a querying mechanism (read or write), don't use relationships and don't put validations in there. I'm sorry, but without relationships - why even use AR for querying? And how? Via connection.select/execute?
  - Fire-Dragon-DoL 6y ago
    It's hard to answer, in the sense that yes, you can use ActiveRecord relationships for the purpose of _building a query_. The point is, you should use them only for that. And it comes with the downsides of distancing you from SQL, which is not negligible. The problem is if you try to access relationships that you didn't load from the object, that shouldn't be done. It's the autoloading from the database that is the real problem. If you have enough discipline and enough authority to ensure that never happens within the software you are working on, you can. It's really culture problem. As soon as you pass around a `user`, someone will type `.posts` on it, or `.save`, suddenly your business logic depends on the database shape, rather than on contracts. What if your database shape is wrong? What if your database shape needs to change? The goal of good architecture is to be resilient to change, or to even _postpone the choice_ to a moment in time where you have more data to make the right one. The safest way is: query with activerecord, map to plain ruby objects and discard the activerecord ones immediately. This will also help you discover the entities you didn't know about, for example, if you have a table of users identified by email, that's the "User" table in Rails. However, let's say that you take only a subset of that table (with select), such as "Full Name" and "Email": this could represent something different. A Newsletter::Subscriber for example. And the newsletter subscriber entity can be used in the Newsletter::Weekly::Send object, as well as the Newsletter::Unsubscribe. If you realize that this should not have been in the users table in the first place (I have no idea myself), the cost of change is way lower than if you passed an activerecord object around. I hope this answers some of your questions. There is a lot to say on the topic. I'm happy to chat more on slack or an online videoconference session
    - jaxn 6y ago
      I am constantly guarding against AR callbacks as well as the insane number of queries that come from lazy loading relationships. Might have to explore your suggestions a bit.
- jjgreen 6y ago
  So why use AR? Sequel is a thing.
- joelbluminator 6y ago
  Not arguing your points, just a wondering: Why stick to Rails then? Without ActiveRecord Rails is a pretty big bloat with a mediocre view layer. Routing is nice but I'm sure Sinatra could do that as well.
  - Fire-Dragon-DoL 6y ago
    The majority of Ruby jobs is on Rails. All I need, personally, is a server like Puma, a router like Roda and the pg gem really. Then of course it depends on the application you need to develop. I would probably need some library to coerce string values to types (boolean, integer) for forms, and a mapping mechanism of some form to convert a pg result in a data shape I control.
dasil003 6y ago
If you are truly sharing logic then it might be okay, but typically I've seen concerns added as a way to organize code when ActiveRecord models get too big. At this point a lot of people reach for Concerns because it is right there in Rails waiting to be used, but ultimately it's just papering over the problem of bloated classes with too many responsibilities. I usually prefer to add some kind of service layer to handle complex manipulation and object lifecycle so that ActiveRecord just manages querying/persistence with most if not all business logic at a higher layer.
- xipho 6y ago
  > it's just papering over the problem of bloated classes with too many responsibilities. If you're blindly coding away and using some feature just because it's there you've got bigger problems with how you go about programming, that's not special to Rails. I find concerns to be an intermediate mechanism to use in migrating the bloat out to some other abstract level. However, adding abstractions beyond MCV has it's own problems, each level means the developer has to understanding something more, one can't escape that. Pretending that one can fully anticipate the complexity of large project and model it perfectly via the way you organize your code is really only something done by the the beginning programmer. Concerns can be very tight, as you note, and of course any feature can be used poorly. I like concerns, we have many that haven't been touched, and lead to an ability to extremely rapidly spread functionality around a huge number of models (e.g. different annotation classes). I'm also guilty of using them in the intermediate manner above. In the long term, one sees these patterns, and doesn't fret about such things.

What's the alternative to sharing logic across ActiveRecord models?

by Axsuul 6y ago

What's the alternative to sharing logic across ActiveRecord models?

I think a different way of looking at the problem is that ActiveRecord models really shouldn’t have much, if any logic. Instead, logic should get delegated to other types of object, such as services, decorators, query objects, etc. While “fat models” is certainly better than “fat controllers”, I’m afraid it lead the Rails community astray with large-scale apps that required more nuanced architecture.

Fire-Dragon-DoL 6y ago

Don't put the logic in activerecord models at all. Not even the data. Use activerecord uniquely as a querying mechanism (read or write), don't use relationships and don't put validations in there. Create objects (aka behavioral objects, aka servoce objects) for the logic and create entities (plain ruby objects) when you need to pass around the data. Yes, you are essentially eliminating the entirety of activerecord. After 10 years of rails, you realize that is the only safe way to use that library. By the way User User::SignUp Are related. The behavior doesn't need to be in the same object, the namespace takes care of that already.

swader999 6y ago
That's a breath of fresh air to read.
megraf 6y ago
You're correct on all fronts. Domain driven design, POROs- all of it. I bet you maintain something nice!
- Fire-Dragon-DoL 6y ago
  Thanks, I really appreciate that. I do my best, but the sad reality is that I made an insanely large amount of mistakes in my development life, I didn't reach these conclusions without doing damage myself. I try to give back by training developers and making sure the business gain awareness so they don't have to experience the complete halt of feature development when the software becomes unsuited for changes.
e12e 6y ago
> Use activerecord uniquely as a querying mechanism (read or write), don't use relationships and don't put validations in there. I'm sorry, but without relationships - why even use AR for querying? And how? Via connection.select/execute?
- Fire-Dragon-DoL 6y ago
  It's hard to answer, in the sense that yes, you can use ActiveRecord relationships for the purpose of _building a query_. The point is, you should use them only for that. And it comes with the downsides of distancing you from SQL, which is not negligible. The problem is if you try to access relationships that you didn't load from the object, that shouldn't be done. It's the autoloading from the database that is the real problem. If you have enough discipline and enough authority to ensure that never happens within the software you are working on, you can. It's really culture problem. As soon as you pass around a `user`, someone will type `.posts` on it, or `.save`, suddenly your business logic depends on the database shape, rather than on contracts. What if your database shape is wrong? What if your database shape needs to change? The goal of good architecture is to be resilient to change, or to even _postpone the choice_ to a moment in time where you have more data to make the right one. The safest way is: query with activerecord, map to plain ruby objects and discard the activerecord ones immediately. This will also help you discover the entities you didn't know about, for example, if you have a table of users identified by email, that's the "User" table in Rails. However, let's say that you take only a subset of that table (with select), such as "Full Name" and "Email": this could represent something different. A Newsletter::Subscriber for example. And the newsletter subscriber entity can be used in the Newsletter::Weekly::Send object, as well as the Newsletter::Unsubscribe. If you realize that this should not have been in the users table in the first place (I have no idea myself), the cost of change is way lower than if you passed an activerecord object around. I hope this answers some of your questions. There is a lot to say on the topic. I'm happy to chat more on slack or an online videoconference session
  - jaxn 6y ago
    I am constantly guarding against AR callbacks as well as the insane number of queries that come from lazy loading relationships. Might have to explore your suggestions a bit.
jjgreen 6y ago
So why use AR? Sequel is a thing.
joelbluminator 6y ago
Not arguing your points, just a wondering: Why stick to Rails then? Without ActiveRecord Rails is a pretty big bloat with a mediocre view layer. Routing is nice but I'm sure Sinatra could do that as well.
- Fire-Dragon-DoL 6y ago
  The majority of Ruby jobs is on Rails. All I need, personally, is a server like Puma, a router like Roda and the pg gem really. Then of course it depends on the application you need to develop. I would probably need some library to coerce string values to types (boolean, integer) for forms, and a mapping mechanism of some form to convert a pg result in a data shape I control.

dasil003 6y ago

If you are truly sharing logic then it might be okay, but typically I've seen concerns added as a way to organize code when ActiveRecord models get too big. At this point a lot of people reach for Concerns because it is right there in Rails waiting to be used, but ultimately it's just papering over the problem of bloated classes with too many responsibilities. I usually prefer to add some kind of service layer to handle complex manipulation and object lifecycle so that ActiveRecord just manages querying/persistence with most if not all business logic at a higher layer.

xipho 6y ago
> it's just papering over the problem of bloated classes with too many responsibilities. If you're blindly coding away and using some feature just because it's there you've got bigger problems with how you go about programming, that's not special to Rails. I find concerns to be an intermediate mechanism to use in migrating the bloat out to some other abstract level. However, adding abstractions beyond MCV has it's own problems, each level means the developer has to understanding something more, one can't escape that. Pretending that one can fully anticipate the complexity of large project and model it perfectly via the way you organize your code is really only something done by the the beginning programmer. Concerns can be very tight, as you note, and of course any feature can be used poorly. I like concerns, we have many that haven't been touched, and lead to an ability to extremely rapidly spread functionality around a huge number of models (e.g. different annotation classes). I'm also guilty of using them in the intermediate manner above. In the long term, one sees these patterns, and doesn't fret about such things.