Potentially dangerous attribute available for mass assignment Open
# frozen_string_literal: true
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Mass assignment is a feature of Rails which allows an application to create a record from the values of a hash.
Example:
User.new(params[:user])
Unfortunately, if there is a user field called admin
which controls administrator access, now any user can make themselves an administrator.
attr_accessible
and attr_protected
can be used to limit mass assignment. However, Brakeman will warn unless attr_accessible
is used, or mass assignment is completely disabled.
There are two different mass assignment warnings which can arise. The first is when mass assignment actually occurs, such as the example above. This results in a warning like
Unprotected mass assignment near line 61: User.new(params[:user])
The other warning is raised whenever a model is found which does not use attr_accessible
. This produces generic warnings like
Mass assignment is not restricted using attr_accessible
with a list of affected models.
In Rails 3.1 and newer, mass assignment can easily be disabled:
config.active_record.whitelist_attributes = true
Unfortunately, it can also easily be bypassed:
User.new(params[:user], :without_protection => true)
Brakeman will warn on uses of without_protection
.
Class Invoice
has 56 methods (exceeds 20 allowed). Consider refactoring. Open
class Invoice < ApplicationRecord
%I[due_on period issued_on last_charging_retry].each do |attr|
attribute attr, :date
end
File invoice.rb
has 426 lines of code (exceeds 250 allowed). Consider refactoring. Open
class Invoice < ApplicationRecord
%I[due_on period issued_on last_charging_retry].each do |attr|
attribute attr, :date
end
Method charge!
has a Cognitive Complexity of 32 (exceeds 5 allowed). Consider refactoring. Open
def charge!(automatic = true)
ensure_payable_state!
unless chargeable?
logger.info "Not charging invoice #{id} (buyer #{buyer_account_id}), reason: #{reason_cannot_charge}"
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Cognitive Complexity
Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.
A method's cognitive complexity is based on a few simple rules:
- Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
- Code is considered more complex for each "break in the linear flow of the code"
- Code is considered more complex when "flow breaking structures are nested"
Further reading
Method charge!
has 43 lines of code (exceeds 25 allowed). Consider refactoring. Open
def charge!(automatic = true)
ensure_payable_state!
unless chargeable?
logger.info "Not charging invoice #{id} (buyer #{buyer_account_id}), reason: #{reason_cannot_charge}"
Invoice#charge! is controlled by argument 'automatic' Open
if automatic
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Control Parameter
is a special case of Control Couple
Example
A simple example would be the "quoted" parameter in the following method:
def write(quoted)
if quoted
write_quoted @value
else
write_unquoted @value
end
end
Fixing those problems is out of the scope of this document but an easy solution could be to remove the "write" method alltogether and to move the calls to "writequoted" / "writeunquoted" in the initial caller of "write".
Invoice#to_xml refers to 'markup' more than self (maybe move it to another class?) Open
markup.invoice!(self)
markup.to_xml
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Feature Envy occurs when a code fragment references another object more often than it references itself, or when several clients do the same series of manipulations on a particular type of object.
Feature Envy reduces the code's ability to communicate intent: code that "belongs" on one class but which is located in another can be hard to find, and may upset the "System of Names" in the host class.
Feature Envy also affects the design's flexibility: A code fragment that is in the wrong class creates couplings that may not be natural within the application's domain, and creates a loss of cohesion in the unwilling host class.
Feature Envy often arises because it must manipulate other objects (usually its arguments) to get them into a useful form, and one force preventing them (the arguments) doing this themselves is that the common knowledge lives outside the arguments, or the arguments are of too basic a type to justify extending that type. Therefore there must be something which 'knows' about the contents or purposes of the arguments. That thing would have to be more than just a basic type, because the basic types are either containers which don't know about their contents, or they are single objects which can't capture their relationship with their fellows of the same type. So, this thing with the extra knowledge should be reified into a class, and the utility method will most likely belong there.
Example
Running Reek on:
class Warehouse
def sale_price(item)
(item.price - item.rebate) * @vat
end
end
would report:
Warehouse#total_price refers to item more than self (FeatureEnvy)
since this:
(item.price - item.rebate)
belongs to the Item class, not the Warehouse.
Invoice has at least 53 methods Open
class Invoice < ApplicationRecord
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Too Many Methods
is a special case of LargeClass
.
Example
Given this configuration
TooManyMethods:
max_methods: 3
and this code:
class TooManyMethods
def one; end
def two; end
def three; end
def four; end
end
Reek would emit the following warning:
test.rb -- 1 warning:
[1]:TooManyMethods has at least 4 methods (TooManyMethods)
Invoice#charge! has approx 25 statements Open
def charge!(automatic = true)
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A method with Too Many Statements
is any method that has a large number of lines.
Too Many Statements
warns about any method that has more than 5 statements. Reek's smell detector for Too Many Statements
counts +1 for every simple statement in a method and +1 for every statement within a control structure (if
, else
, case
, when
, for
, while
, until
, begin
, rescue
) but it doesn't count the control structure itself.
So the following method would score +6 in Reek's statement-counting algorithm:
def parse(arg, argv, &error)
if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
return nil, block, nil # +1
end
opt = (val = parse_arg(val, &error))[1] # +2
val = conv_arg(*val) # +3
if opt and !arg
argv.shift # +4
else
val[0] = nil # +5
end
val # +6
end
(You might argue that the two assigments within the first @if@ should count as statements, and that perhaps the nested assignment should count as +2.)
Invoice#charge! has boolean parameter 'automatic' Open
def charge!(automatic = true)
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Boolean Parameter
is a special case of Control Couple
, where a method parameter is defaulted to true or false. A Boolean Parameter effectively permits a method's caller to decide which execution path to take. This is a case of bad cohesion. You're creating a dependency between methods that is not really necessary, thus increasing coupling.
Example
Given
class Dummy
def hit_the_switch(switch = true)
if switch
puts 'Hitting the switch'
# do other things...
else
puts 'Not hitting the switch'
# do other things...
end
end
end
Reek would emit the following warning:
test.rb -- 3 warnings:
[1]:Dummy#hit_the_switch has boolean parameter 'switch' (BooleanParameter)
[2]:Dummy#hit_the_switch is controlled by argument switch (ControlParameter)
Note that both smells are reported, Boolean Parameter
and Control Parameter
.
Getting rid of the smell
This is highly dependent on your exact architecture, but looking at the example above what you could do is:
- Move everything in the
if
branch into a separate method - Move everything in the
else
branch into a separate method - Get rid of the
hit_the_switch
method alltogether - Make the decision what method to call in the initial caller of
hit_the_switch
Invoice#cost has boolean parameter 'vat_included' Open
def cost(vat_included: true, rounding: CHARGE_PRECISION)
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Boolean Parameter
is a special case of Control Couple
, where a method parameter is defaulted to true or false. A Boolean Parameter effectively permits a method's caller to decide which execution path to take. This is a case of bad cohesion. You're creating a dependency between methods that is not really necessary, thus increasing coupling.
Example
Given
class Dummy
def hit_the_switch(switch = true)
if switch
puts 'Hitting the switch'
# do other things...
else
puts 'Not hitting the switch'
# do other things...
end
end
end
Reek would emit the following warning:
test.rb -- 3 warnings:
[1]:Dummy#hit_the_switch has boolean parameter 'switch' (BooleanParameter)
[2]:Dummy#hit_the_switch is controlled by argument switch (ControlParameter)
Note that both smells are reported, Boolean Parameter
and Control Parameter
.
Getting rid of the smell
This is highly dependent on your exact architecture, but looking at the example above what you could do is:
- Move everything in the
if
branch into a separate method - Move everything in the
else
branch into a separate method - Get rid of the
hit_the_switch
method alltogether - Make the decision what method to call in the initial caller of
hit_the_switch
Invoice#cost is controlled by argument 'rounding' Open
if rounding
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Control Parameter
is a special case of Control Couple
Example
A simple example would be the "quoted" parameter in the following method:
def write(quoted)
if quoted
write_quoted @value
else
write_unquoted @value
end
end
Fixing those problems is out of the scope of this document but an easy solution could be to remove the "write" method alltogether and to move the calls to "writequoted" / "writeunquoted" in the initial caller of "write".
Invoice#cost is controlled by argument 'vat_included' Open
sum = vat_included ? exact_cost_with_vat : exact_cost_without_vat
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Control Parameter
is a special case of Control Couple
Example
A simple example would be the "quoted" parameter in the following method:
def write(quoted)
if quoted
write_quoted @value
else
write_unquoted @value
end
end
Fixing those problems is out of the scope of this document but an easy solution could be to remove the "write" method alltogether and to move the calls to "writequoted" / "writeunquoted" in the initial caller of "write".
Invoice#charge! calls 'provider.billing_strategy' 2 times Open
provider.billing_strategy&.info("Invoice #{id} (buyer #{buyer_account_id}) for period #{period} was charged, marking as paid", buyer)
pay!
else
logger.info("Invoice #{id} (buyer #{buyer_account_id}) was not charged")
false
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Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Invoice assumes too much for instance variable '@period' Open
class Invoice < ApplicationRecord
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Classes should not assume that instance variables are set or present outside of the current class definition.
Good:
class Foo
def initialize
@bar = :foo
end
def foo?
@bar == :foo
end
end
Good as well:
class Foo
def foo?
bar == :foo
end
def bar
@bar ||= :foo
end
end
Bad:
class Foo
def go_foo!
@bar = :foo
end
def foo?
@bar == :foo
end
end
Example
Running Reek on:
class Dummy
def test
@ivar
end
end
would report:
[1]:InstanceVariableAssumption: Dummy assumes too much for instance variable @ivar
Note that this example would trigger this smell warning as well:
class Parent
def initialize(omg)
@omg = omg
end
end
class Child < Parent
def foo
@omg
end
end
The way to address the smell warning is that you should create an attr_reader
to use @omg
in the subclass and not access @omg
directly like this:
class Parent
attr_reader :omg
def initialize(omg)
@omg = omg
end
end
class Child < Parent
def foo
omg
end
end
Directly accessing instance variables is considered a smell because it breaks encapsulation and makes it harder to reason about code.
If you don't want to expose those methods as public API just make them private like this:
class Parent
def initialize(omg)
@omg = omg
end
private
attr_reader :omg
end
class Child < Parent
def foo
omg
end
end
Current Support in Reek
An instance variable must:
- be set in the constructor
- or be accessed through a method with lazy initialization / memoization.
If not, Instance Variable Assumption will be reported.
Invoice#charge! calls 'Rails.application' 2 times Open
Rails.application.config.event_store.publish_event(event)
else
logger.info("Marking invoice #{id} (buyer #{buyer_account_id}) as failed (too many retries)")
fail!
# TODO: Decouple the notification to observer and delete the IF
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Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Invoice#charge! calls 'provider_account.provider_can_use?(:new_notification_system)' 2 times Open
unless provider_account.provider_can_use?(:new_notification_system)
InvoiceMessenger.unsuccessfully_charged_for_provider(self).deliver
end
event = Invoices::UnsuccessfullyChargedInvoiceProviderEvent.create(self)
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Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Invoice#charge! calls 'Rails.application.config' 2 times Open
Rails.application.config.event_store.publish_event(event)
else
logger.info("Marking invoice #{id} (buyer #{buyer_account_id}) as failed (too many retries)")
fail!
# TODO: Decouple the notification to observer and delete the IF
- Read upRead up
- Exclude checks
Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Invoice#charge! calls 'Rails.application.config.event_store' 2 times Open
Rails.application.config.event_store.publish_event(event)
else
logger.info("Marking invoice #{id} (buyer #{buyer_account_id}) as failed (too many retries)")
fail!
# TODO: Decouple the notification to observer and delete the IF
- Read upRead up
- Exclude checks
Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Invoice#charge! calls 'Rails.application.config.event_store.publish_event(event)' 2 times Open
Rails.application.config.event_store.publish_event(event)
else
logger.info("Marking invoice #{id} (buyer #{buyer_account_id}) as failed (too many retries)")
fail!
# TODO: Decouple the notification to observer and delete the IF
- Read upRead up
- Exclude checks
Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Invoice has missing safe method 'ensure_payable_state!' Wontfix
def ensure_payable_state!
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A candidate method for the Missing Safe Method
smell are methods whose names end with an exclamation mark.
An exclamation mark in method names means (the explanation below is taken from here ):
The ! in method names that end with ! means, “This method is dangerous”—or, more precisely, this method is the “dangerous” version of an otherwise equivalent method, with the same name minus the !. “Danger” is relative; the ! doesn’t mean anything at all unless the method name it’s in corresponds to a similar but bang-less method name. So, for example, gsub! is the dangerous version of gsub. exit! is the dangerous version of exit. flatten! is the dangerous version of flatten. And so forth.
Such a method is called Missing Safe Method
if and only if her non-bang version does not exist and this method is reported as a smell.
Example
Given
class C
def foo; end
def foo!; end
def bar!; end
end
Reek would report bar!
as Missing Safe Method
smell but not foo!
.
Reek reports this smell only in a class context, not in a module context in order to allow perfectly legit code like this:
class Parent
def foo; end
end
module Dangerous
def foo!; end
end
class Son < Parent
include Dangerous
end
class Daughter < Parent
end
In this example, Reek would not report the Missing Safe Method
smell for the method foo
of the Dangerous
module.
Invoice has missing safe method 'charge!' Open
def charge!(automatic = true)
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A candidate method for the Missing Safe Method
smell are methods whose names end with an exclamation mark.
An exclamation mark in method names means (the explanation below is taken from here ):
The ! in method names that end with ! means, “This method is dangerous”—or, more precisely, this method is the “dangerous” version of an otherwise equivalent method, with the same name minus the !. “Danger” is relative; the ! doesn’t mean anything at all unless the method name it’s in corresponds to a similar but bang-less method name. So, for example, gsub! is the dangerous version of gsub. exit! is the dangerous version of exit. flatten! is the dangerous version of flatten. And so forth.
Such a method is called Missing Safe Method
if and only if her non-bang version does not exist and this method is reported as a smell.
Example
Given
class C
def foo; end
def foo!; end
def bar!; end
end
Reek would report bar!
as Missing Safe Method
smell but not foo!
.
Reek reports this smell only in a class context, not in a module context in order to allow perfectly legit code like this:
class Parent
def foo; end
end
module Dangerous
def foo!; end
end
class Son < Parent
include Dangerous
end
class Daughter < Parent
end
In this example, Reek would not report the Missing Safe Method
smell for the method foo
of the Dangerous
module.
Invoice has missing safe method 'issue_and_pay_if_free!' Open
def issue_and_pay_if_free!
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A candidate method for the Missing Safe Method
smell are methods whose names end with an exclamation mark.
An exclamation mark in method names means (the explanation below is taken from here ):
The ! in method names that end with ! means, “This method is dangerous”—or, more precisely, this method is the “dangerous” version of an otherwise equivalent method, with the same name minus the !. “Danger” is relative; the ! doesn’t mean anything at all unless the method name it’s in corresponds to a similar but bang-less method name. So, for example, gsub! is the dangerous version of gsub. exit! is the dangerous version of exit. flatten! is the dangerous version of flatten. And so forth.
Such a method is called Missing Safe Method
if and only if her non-bang version does not exist and this method is reported as a smell.
Example
Given
class C
def foo; end
def foo!; end
def bar!; end
end
Reek would report bar!
as Missing Safe Method
smell but not foo!
.
Reek reports this smell only in a class context, not in a module context in order to allow perfectly legit code like this:
class Parent
def foo; end
end
module Dangerous
def foo!; end
end
class Son < Parent
include Dangerous
end
class Daughter < Parent
end
In this example, Reek would not report the Missing Safe Method
smell for the method foo
of the Dangerous
module.
Invoice has missing safe method 'generate_pdf!' Open
def generate_pdf!
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A candidate method for the Missing Safe Method
smell are methods whose names end with an exclamation mark.
An exclamation mark in method names means (the explanation below is taken from here ):
The ! in method names that end with ! means, “This method is dangerous”—or, more precisely, this method is the “dangerous” version of an otherwise equivalent method, with the same name minus the !. “Danger” is relative; the ! doesn’t mean anything at all unless the method name it’s in corresponds to a similar but bang-less method name. So, for example, gsub! is the dangerous version of gsub. exit! is the dangerous version of exit. flatten! is the dangerous version of flatten. And so forth.
Such a method is called Missing Safe Method
if and only if her non-bang version does not exist and this method is reported as a smell.
Example
Given
class C
def foo; end
def foo!; end
def bar!; end
end
Reek would report bar!
as Missing Safe Method
smell but not foo!
.
Reek reports this smell only in a class context, not in a module context in order to allow perfectly legit code like this:
class Parent
def foo; end
end
module Dangerous
def foo!; end
end
class Son < Parent
include Dangerous
end
class Daughter < Parent
end
In this example, Reek would not report the Missing Safe Method
smell for the method foo
of the Dangerous
module.
Invoice#issued? performs a nil-check Open
!issued_on.nil?
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A NilCheck
is a type check. Failures of NilCheck
violate the "tell, don't ask" principle.
Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.
Example
Given
class Klass
def nil_checker(argument)
if argument.nil?
puts "argument isn't nil!"
end
end
end
Reek would emit the following warning:
test.rb -- 1 warning:
[3]:Klass#nil_checker performs a nil-check. (NilCheck)
Invoice#next_transition_from_state has the variable name 't' Open
state_transitions.find {|t| t.to == state.to_s }
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An Uncommunicative Variable Name
is a variable name that doesn't communicate its intent well enough.
Poor names make it hard for the reader to build a mental picture of what's going on in the code. They can also be mis-interpreted; and they hurt the flow of reading, because the reader must slow down to interpret the names.