DEALING WITH

OBESE MODELS

A 5 Step Guide to Getting your models in shape

Ryan Brunner, Influitive

@ryanbrunner

THE

PROBLEM

My Models scare me. They’re too big and hard to deal with.

Usually, when I run into a structural problem with Rails, there’s one place I can turn to.

CONVENTIONS

CONVENTIONS

Your folders should look like this.

Your views should look like this.

Your controllers should look like this.

Your stylesheets should look like this.

Your javascript should apparently look like this.

SO WHY IS THIS

OK FOR YOUR

MODELS?

IS THERE A

RAILS

CONVENTION

TO DEAL WITH

THIS?

FAT MODELS

SKINNY CONTROLLERS

MAYBE FAT

MODELS AREN’T

THE

SOLUTION…

FAT MODELS

SKINNY CONTROLLERS

REASONABLY HEALTHY MODELS

EXAMPLE

TIME!

Let’s build a person model!

PERSON • Attributes

PERSON • Attributes

• Associations

PERSON • Attributes

• Associations

• Validation

• Attributes

• Associations

• Validation

• Scopes for searching

PERSON

• Attributes

• Associations

• Validation

• Scopes for searching

• Scopes for authorization

PERSON

• Attributes

• Associations

• Validation

• Scopes for searching

• Scopes for authorization

• State Machine

PERSON

• Attributes

• Associations

• Validation

• Scopes for searching

• Scopes for authorization

• State Machine

• Location / GeoTagging Stuff

PERSON

• Attributes

• Associations

• Validation

• Scopes for searching

• Scopes for authorization

• State Machine

• Location / GeoTagging Stuff

• Leaderboard

PERSON

• Attributes

• Associations

• Validation

• Scopes for searching

• Scopes for authorization

• State Machine

• Location / GeoTagging Stuff

• Leaderboard

• Relationship helper methods

PERSON

• Attributes

• Associations

• Validation

• Scopes for searching

• Scopes for authorization

• State Machine

• Location / GeoTagging Stuff

• Leaderboard

• Relationship helper methods

• Formatting methods

PERSON

WHAT

HAPPENED?

OBESITY

It’s not just for Texas anymore.

LET’S GET

OUR MODEL

BACK IN

SHAPE!

STEP 1:

ORGANIZATION

BIG,

BEAUTIFUL

MODELS

SHOULD BE

ORGANIZED.

BIG,

BEAUTIFUL

MODELS

SHOULD BE

ORGANIZED.

WHITESPACE

IS YOUR

FRIEND.

BIG,

BEAUTIFUL

MODELS

SHOULD BE

ORGANIZED.

WHITESPACE

IS YOUR

FRIEND.

DON’T BE

AFRAID OF

COMMENTS.

BIG,

BEAUTIFUL

MODELS

SHOULD BE

ORGANIZED.

WHITESPACE

IS YOUR

FRIEND.

DON’T BE

AFRAID OF

COMMENTS.

PLAY AROUND

WITH

INDENTING.

STEP 2:

RELOCATING

LOOK FOR

CODE THAT’S

TOO

INTERESTED

IN ANOTHER

MODEL.

person.rb

LOOK FOR

CODE THAT’S

TOO

INTERESTED

IN ANOTHER

MODEL.

person.rb

IT MIGHT

MAKE MORE

SENSE TO

MOVE IT

THERE.

person.rb

feedback.rb

LOOK FOR

CODE THAT’S

TOO

INTERESTED

IN ANOTHER

MODEL.

person.rb

IT MIGHT

MAKE MORE

SENSE TO

MOVE IT

THERE.

person.rb

feedback.rb

FATNESS

ISN’T JUST

ABOUT LOC.

STEP 3:

ABSTRACTING

COMMON

BEHAVIOUR

SOMETIMES

THINGS

AREN’T

CENTRAL TO

YOUR MODEL.

SOMETIMES

THINGS

AREN’T

CENTRAL TO

YOUR MODEL.

BUILD YOUR

OWN

FRAMEWORK.

SOMETIMES

THINGS

AREN’T

CENTRAL TO

YOUR MODEL.

BUILD YOUR

OWN

FRAMEWORK.

EVEN IF YOU

ONLY DO IT

ONCE.

STEP 4:

PRESENTATION

LOGIC

WATCH FOR

PRESENTATION

LOGIC IN YOUR

MODELS

CONSIDER

HTML

HARMFUL.

MODELS

SHOULDN’T

FORMAT DATA.

IF YOU’RE

RETURNING

SOMETHING

OTHER THAN

MODELS, BE

CAREFUL..

THE

TRADITIONAL

RAILS

SOLUTION -

HELPERS

BUT..

HELPERS

SUCK WHEN

YOU DEPEND

ON STATE.

DECORATORS

Like Helpers, but don’t suck.

• Delegates methods to the subject of the decorator.

• Provides additional methods for presentation logic.

• Use them like you’d use the model, but feel free to add presentation logic.

ANATOMY OF

A DECORATOR

DECORATORS

ARE A WAY TO

EXTEND YOUR

MODELS TO

ADD

PRESENTATION

LOGIC

ALL THE DELEGATION WORK IS DONE FOR YOU.

https://github.com/jcasimir/rails_decorators

STEP 5:

PRESENTERS

EXAMPLE

TIME!

Relationship Viewer

WE NEEDED THIS

INTERFACE.

IT NEEDS TO

INTERACT WITH

FILTERED

RELATIONSHIPS

IN A LOT OF

DIFFERENT WAYS

ALL WE NEED IS

METHODS FOR:

• Whether the current user is connected.

• Counts of all connections filtered by customer type.

• Lists of relationships by relationship type.

• Whether the user has submitted feedback.

• How many users are currently in the system.

• Content linked to those users.

PHEW!

That there’s a lot of stuff.

ATTEMPT #1

Let’s fatten up some models.

relationship.rb

relationships_controller.rb

LET’S ADD A

PRESENTER!

prospect_match_presenter.rb

prospect_match_controller.rb

CLEAN,

WONDERFUL

VIEWS

WHY USE

PRESENTERS?

• Your models are concerned only with what they do.

• Your controllers and views talk to a well-defined interface.

WHEN TO

USE A

PRESENTER

• Your view talks about more than one model (in a poorly related way)

• You have lots of instance variables on your controller action.

• Your model is too clever about things it isn’t related to.

READY FOR

BEACH

SEASON

SUMMARY

1. Sweat the easy stuff first.

2. Organization goes a long way.

3. Limit how much your models know about other things.

4. Consider presenters or decorators for complicated scenarios.