Class: FService::Result::Failure

Inherits:
Base
  • Object
show all
Defined in:
lib/f_service/result/failure.rb

Overview

Represents a value of a failed operation. The error field can contain any information you want.

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#on_failure, #on_success, #to_ary, #type

Constructor Details

#initialize(error, types = []) ⇒ Failure

Creates a failed operation. You usually shouldn’t call this directly. See Base#Failure.

Parameters:

  • error (Object) —

    failure value.



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# File 'lib/f_service/result/failure.rb', line 23

def initialize(error, types = [])
  super(types)
  @error = error
end

Instance Attribute Details

#error ⇒ Object (readonly)

Returns the provided error for the result.

Returns:

  • (Object) —

    the provided error for the result



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# File 'lib/f_service/result/failure.rb', line 16

class Failure < Result::Base
  attr_reader :error

  # Creates a failed operation.
  # You usually shouldn't call this directly. See {FService::Base#Failure}.
  #
  # @param error [Object] failure value.
  def initialize(error, types = [])
    super(types)
    @error = error
  end

  # Returns false.
  #
  #
  # @example
  #   # Suppose that User::Update returns an FService::Result
  #
  #   log_errors(user) unless User::Update.(user: user).successful?
  def successful?
    false
  end

  # Returns true.
  #
  #
  # @example
  #   # Suppose that User::Update returns an FService::Result
  #
  #   log_errors(user) if User::Update.(user: user).failed?
  def failed?
    true
  end

  # Failed operations do not have value.
  def value
    nil
  end

  # Raises an exception if called.
  # (see #value)
  def value!
    raise Result::Error, 'Failure objects do not have value'
  end

  # Returns the current error to the given block.
  # Use this to chain multiple service calls (since all services return Results).
  # It works just like the `.and_then` method, but only runs if the result is a Failure.
  #
  #
  # @example
  #   class UpdateUserOnExternalService
  #     attribute :user_params
  #
  #     def run
  #       check_api_status
  #         .and_then { update_user }
  #         .or_else { create_update_worker }
  #     end
  #
  #     private
  #     # some code
  #   end
  #
  # @yieldparam error pass {#error} to a block
  # @yieldparam type pass {#type} to a block
  def catch
    yield(*to_ary)
  end

  alias or_else catch

  # Returns itself to the given block.
  # Use this to chain multiple service calls (since all services return Results).
  # It will short circuit your service call chain.
  #
  #
  # @example
  #   class UsersController < BaseController
  #     def create
  #       result = User::Create.(user_params) # if this fails the following calls won't run
  #                            .and_then { |user| User::SendWelcomeEmail.(user: user) }
  #                            .and_then { |user| User::Login.(user: user) }
  #
  #       if result.successful?
  #         json_success(result.value)
  #       else
  #         json_error(result.error)
  #       end
  #     end
  #   end
  #
  # @return [self]
  def and_then
    self
  end

  # See #and_then
  def then
    FService.deprecate!(name: "#{self.class}##{__method__}", alternative: '#and_then', from: caller[0])
    and_then
  end

  # Outputs a string representation of the object
  #
  #
  # @example
  #   puts FService::Result::Failure.new("Oh no!")
  #   # => Failure("Oh no!")
  #
  # @return [String] the object's string representation
  def to_s
    error.nil? ? 'Failure()' : "Failure(#{error.inspect})"
  end
end

#types ⇒ Object (readonly)

Returns the provided types for the result. Defaults to nil.

Returns:

  • (Object) —

    the provided types for the result. Defaults to nil.



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# File 'lib/f_service/result/failure.rb', line 16

class Failure < Result::Base
  attr_reader :error

  # Creates a failed operation.
  # You usually shouldn't call this directly. See {FService::Base#Failure}.
  #
  # @param error [Object] failure value.
  def initialize(error, types = [])
    super(types)
    @error = error
  end

  # Returns false.
  #
  #
  # @example
  #   # Suppose that User::Update returns an FService::Result
  #
  #   log_errors(user) unless User::Update.(user: user).successful?
  def successful?
    false
  end

  # Returns true.
  #
  #
  # @example
  #   # Suppose that User::Update returns an FService::Result
  #
  #   log_errors(user) if User::Update.(user: user).failed?
  def failed?
    true
  end

  # Failed operations do not have value.
  def value
    nil
  end

  # Raises an exception if called.
  # (see #value)
  def value!
    raise Result::Error, 'Failure objects do not have value'
  end

  # Returns the current error to the given block.
  # Use this to chain multiple service calls (since all services return Results).
  # It works just like the `.and_then` method, but only runs if the result is a Failure.
  #
  #
  # @example
  #   class UpdateUserOnExternalService
  #     attribute :user_params
  #
  #     def run
  #       check_api_status
  #         .and_then { update_user }
  #         .or_else { create_update_worker }
  #     end
  #
  #     private
  #     # some code
  #   end
  #
  # @yieldparam error pass {#error} to a block
  # @yieldparam type pass {#type} to a block
  def catch
    yield(*to_ary)
  end

  alias or_else catch

  # Returns itself to the given block.
  # Use this to chain multiple service calls (since all services return Results).
  # It will short circuit your service call chain.
  #
  #
  # @example
  #   class UsersController < BaseController
  #     def create
  #       result = User::Create.(user_params) # if this fails the following calls won't run
  #                            .and_then { |user| User::SendWelcomeEmail.(user: user) }
  #                            .and_then { |user| User::Login.(user: user) }
  #
  #       if result.successful?
  #         json_success(result.value)
  #       else
  #         json_error(result.error)
  #       end
  #     end
  #   end
  #
  # @return [self]
  def and_then
    self
  end

  # See #and_then
  def then
    FService.deprecate!(name: "#{self.class}##{__method__}", alternative: '#and_then', from: caller[0])
    and_then
  end

  # Outputs a string representation of the object
  #
  #
  # @example
  #   puts FService::Result::Failure.new("Oh no!")
  #   # => Failure("Oh no!")
  #
  # @return [String] the object's string representation
  def to_s
    error.nil? ? 'Failure()' : "Failure(#{error.inspect})"
  end
end

Instance Method Details

#and_then ⇒ self

Returns itself to the given block. Use this to chain multiple service calls (since all services return Results). It will short circuit your service call chain.

Examples:

class UsersController < BaseController
  def create
    result = User::Create.(user_params) # if this fails the following calls won't run
                         .and_then { |user| User::SendWelcomeEmail.(user: user) }
                         .and_then { |user| User::Login.(user: user) }

    if result.successful?
      json_success(result.value)
    else
      json_error(result.error)
    end
  end
end

Returns:

  • (self) 


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# File 'lib/f_service/result/failure.rb', line 109

def and_then
  self
end

#catch {|error, type| ... } ⇒ Object Also known as: or_else

Returns the current error to the given block. Use this to chain multiple service calls (since all services return Results). It works just like the ‘.and_then` method, but only runs if the result is a Failure.

Examples:

class UpdateUserOnExternalService
  attribute :user_params

  def run
    check_api_status
      .and_then { update_user }
      .or_else { create_update_worker }
  end

  private
  # some code
end

Yield Parameters:



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# File 'lib/f_service/result/failure.rb', line 82

def catch
  yield(*to_ary)
end

#failed? ⇒ Boolean

Returns true.

Examples:

# Suppose that User::Update returns an FService::Result

log_errors(user) if User::Update.(user: user).failed?

Returns:

  • (Boolean) 


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# File 'lib/f_service/result/failure.rb', line 46

def failed?
  true
end

#successful? ⇒ Boolean

Returns false.

Examples:

# Suppose that User::Update returns an FService::Result

log_errors(user) unless User::Update.(user: user).successful?

Returns:

  • (Boolean) 


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# File 'lib/f_service/result/failure.rb', line 35

def successful?
  false
end

#then ⇒ Object

See #and_then



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# File 'lib/f_service/result/failure.rb', line 114

def then
  FService.deprecate!(name: "#{self.class}##{__method__}", alternative: '#and_then', from: caller[0])
  and_then
end

#to_s ⇒ String

Outputs a string representation of the object

Examples:

puts FService::Result::Failure.new("Oh no!")
# => Failure("Oh no!")

Returns:

  • (String) —

    the object’s string representation



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# File 'lib/f_service/result/failure.rb', line 127

def to_s
  error.nil? ? 'Failure()' : "Failure(#{error.inspect})"
end

#value ⇒ Object

Failed operations do not have value.



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# File 'lib/f_service/result/failure.rb', line 51

def value
  nil
end

#value! ⇒ Object

Raises an exception if called. (see #value)

Raises:



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# File 'lib/f_service/result/failure.rb', line 57

def value!
  raise Result::Error, 'Failure objects do not have value'
end