Introduce an abstract serializer class

[nesaulov]

#59

[nesaulov]

@AlessandroMinali haven't I missed something?

[nesaulov]

I have added possibility to pass context inside serializer constructor: for objects that are not coupled with serializable model, but still have to be accessed from the inside (I guess it will be current_user in most cases)
Usage:

class IncomeSerializer < Surrealist::Serializer
  json_schema { { amount: Integer } }
  
  def amount
    current_user.guest? ? 100000000 : object.amount
  end
  
  def current_user
    context[:current_user]
  end
end

class Income
  include Surrealist
  surrealize_with IncomeSerializer
  
  attr_reader :amount
  
  def initialize(amount)
    @amount = amount
  end  
end

income = Income.new(200)
IncomeSerializer.new(income, current_user: GuestUser.new).surrealize
# => '{ "amount": 100000000 }'

IncomeSerializer.new(income, current_user: User.find(3)).surrealize
# => '{ "amount": 200 }'

Also I will write good docs for all of this, but a bit after the feature itself.

[AlessandroMinali]

Looks good. Context passing seems a little weird (but functional), but the only alternatives I can think of is using method missing or a branch condition on every method call to check a hash of valid functions which will just be slow.

Maybe this could be another DSL (at the cost of adding more complexity for a low use case, maybe not worth)?

class IncomeSerializer < Surrealist::Serializer
  json_schema { { amount: Integer } }
  serializer_context :current_user, :something, :else
  
  def amount
    current_user.guest? ? 100000000 : object.amount
  end
end

[houndci-bot]

Extra blank line detected.

[houndci-bot]

Extra blank line detected.

[nesaulov]

@AlessandroMinali I think this DSL might be useful, but we should give it a thought. For now I suggest to merge this PR, if there are no problems or suggestions, and to file an issue concerning the DSL you proposed where we could cover all pros and cons.