deprecating activerecord attributes without making zombies
TRANSCRIPT
-Friday, May 10, 13
YANN ARMAND
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@yarmand
Friday, May 10, 13
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The Enterprise Social Network
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DELETE A DB COLUMNWITHOUT MAKING ZOMBIES
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DELETE A DB COLUMNWITHOUT MAKING ZOMBIES
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WHY DELETE A MODEL ATTRIBUTE ?
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WHY DELETE A MODEL ATTRIBUTE ?
•Not used anymore
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WHY DELETE A MODEL ATTRIBUTE ?
•Not used anymore
User Payment card• card_type• card_number
•Move to another model
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KILLING AN ACTIVE RECORD FIELD
Cons
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KILLING AN ACTIVE RECORD FIELD
•Code dependency
Cons
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KILLING AN ACTIVE RECORD FIELD
•Code dependency
Cons
•Unknown impact on the app behavior
-Friday, May 10, 13
KILLING AN ACTIVE RECORD FIELD
•Code dependency
Cons
•Unknown impact on the app behavior
-Friday, May 10, 13
KILLING AN ACTIVE RECORD FIELD
•Code dependency
Cons
•Unknown impact on the app behavior
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KILL AN ACTIVE RECORD FIELD
Pros
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KILL AN ACTIVE RECORD FIELD
Pros
•Reduce Technical Debt
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KILL AN ACTIVE RECORD FIELD
Pros
•Reduce Technical Debt
• Smaller code base
• Lower barrier of entry
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• Eliminate black holes
• Prevent crashes
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BE PREPARED !!
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BE PREPARED !!
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BE PREPARED !!
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class User deprecate_attribute :card_type deprecate_attribute :card_numberend
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API OUTPUT
render :json => user
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
name: 'roger'age: 23
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API OUTPUT
render :json => user
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
name: 'roger'age: 23
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ActiveRecord#serializable_hash
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API OUTPUT
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class User alias_method :super_serializable_hash, :serializable_hash
def serializable_hash(options = {}) options.merge! { :only => self.attributes.keys.map(&:to_sym) - (self.class.deprecated_attributes || []).map(&:to_sym) } super_serializable_hash(options) endend
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API OUTPUT
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class User alias_method :super_serializable_hash, :serializable_hash
def serializable_hash(options = {}) options.merge! { :only => self.attributes.keys.map(&:to_sym) - (self.class.deprecated_attributes || []).map(&:to_sym) } super_serializable_hash(options) endend
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API OUTPUT
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class User alias_method :super_serializable_hash, :serializable_hash
def serializable_hash(options = {}) options.merge! { :only => self.attributes.keys.map(&:to_sym) - (self.class.deprecated_attributes || []).map(&:to_sym) } super_serializable_hash(options) endend
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API OUTPUT
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class User alias_method :super_serializable_hash, :serializable_hash
def serializable_hash(options = {}) options.merge! { :only => self.attributes.keys.map(&:to_sym) - (self.class.deprecated_attributes || []).map(&:to_sym) } super_serializable_hash(options) endend
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ACCESSORS =
[ '',
'=',
'_before_type_cast',
'?',
'_changed?',
'_change',
'_will_change!',
'_was']Zombie Radar
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FIELD HUNTING
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def deprecate_attribute attr msg = "You can't access atribute #{attr}, it has been deprecated" ACCESSORS.each do |term|
define_method("#{attr}#{term}") do |*args| raise DeprecatedAttributeError, msg super end endend
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def deprecate_attribute attr msg = "You can't access atribute #{attr}, it has been deprecated" ACCESSORS.each do |term|
define_method("#{attr}#{term}") do |*args| raise DeprecatedAttributeError, msg super end endend
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def deprecate_attribute attr msg = "You can't access atribute #{attr}, it has been deprecated" ACCESSORS.each do |term|
define_method("#{attr}#{term}") do |*args| raise DeprecatedAttributeError, msg super end endend
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def deprecate_attribute attr msg = "You can't access atribute #{attr}, it has been deprecated" ACCESSORS.each do |term|
define_method("#{attr}#{term}") do |*args| raise DeprecatedAttributeError, msg super end endend
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def deprecate_attribute attr msg = "You can't access atribute #{attr}, it has been deprecated" ACCESSORS.each do |term|
define_method("#{attr}#{term}") do |*args| raise DeprecatedAttributeError, msg super end endend
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def deprecate_attribute attr msg = "You can't access atribute #{attr}, it has been deprecated" ACCESSORS.each do |term|
define_method("#{attr}#{term}") do |*args| raise DeprecatedAttributeError, msg super end endend
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class ApplicationController rescue_from DeprecatedAttributeError, :with => :log_deprecate private
def log_deprecated e deprecated_logger.error(e.backtrace.join("\n"))
e.continue end
end
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cmaruz/continuable
class ApplicationController rescue_from DeprecatedAttributeError, :with => :log_deprecate private
def log_deprecated e deprecated_logger.error(e.backtrace.join("\n"))
e.continue end
end
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REFACTOR
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REFACTOR
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DEPLOY
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REFACTOR
New Code
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DEPLOY
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REFACTOR
MigrationNew Code
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DEPLOY
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REFACTOR
MigrationNew Code
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DEPLOY
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WHAT HAPPENS ?
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
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TimeIn Cache
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WHAT HAPPENS ?
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
Deploy
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TimeIn Cache
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WHAT HAPPENS ?
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
Deploy
name: 'roger'age: 24card_type: 'visa'card_number: 123412341234
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TimeIn Cache Update
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WHAT HAPPENS ?
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
Deploy
name: 'roger'age: 24card_type: 'visa'card_number: 123412341234
Save
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TimeIn Cache Update
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WHAT HAPPENS ?
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
Deploy
name: 'roger'age: 24card_type: 'visa'card_number: 123412341234
Save
Database Exceptionunknown columns
card_type, card_number
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TimeIn Cache Update
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WHAT HAPPENS ?
name: 'roger'age: 23card_type: 'visa'card_number: 123412341234
Deploy
name: 'roger'age: 24card_type: 'visa'card_number: 123412341234
Save
Database Exceptionunknown columns
card_type, card_number
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TimeIn Cache Update
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IGNORE COLUMNS
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class User def columns self.class.columns.reject do |c| (self.class.deprecated_attributes || []).include? c.name.to_s end endend
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THANK YOU !!
https://github.com/yarmand/acread
Acread
-Friday, May 10, 13