houdini/lib/json_resp.rb

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# Provide a declarative json validation and error responses for the rails 'render' method in controllers
#
# The return value of the block you pass into #when_valid should look like {status: code, json: data}
#
# Concerns of this lib are:
# * Validate the params, only running a block when valid
# * Provide a declarative system for request parameter requirements
# * Respond with proper codes and error messages for everything
class JsonResp
attr_accessor :errors
def initialize(params, &block)
@params = params
validation = JsonResp::Validation.new(params)
validation.instance_exec(params, &block)
@errors = validation.errors
return self
end
def when_valid(&block)
return {status: 422, json: {errors: @errors}} if @errors.any?
begin
@response = block.call(@params)
rescue Exception => e
@response = {status: 500, json: {error: "We're sorry, but something went wrong. We've been notified about this issue."}}
puts e
puts e.backtrace.first(10)
end
return @response
end
# Validation of a set of request parameters
class Validation
attr_accessor :errors, :params
def initialize(params)
@params = params
@errors = []
return self
end
def requires(*keys)
@errors.concat keys.select{|k| @params[k].blank? }.map{|k| "#{k} required"}
return Param.new(keys, @errors, @params)
end
def requires_either(key1, key2)
error_message = "#{key1} or #{key2} is required"
if @params[key1].blank? && @params[key2].blank?
@errors << error_message
else
@errors.concat [key1, key2].select{|k| @params[k].blank? }.map{|k| "#{k} required"}
end
return Param.new([key1, key2], @errors, @params)
end
def optional(*keys)
keys_to_check = keys.select{|k| @params[k].present?}
return Param.new(keys_to_check, @errors, @params)
end
end
class Param
# param validation methods
# To make more validators, you can extend this class
# All methods here are no-ops if the key was optional and is not present
attr_accessor :keys, :errors, :params
def initialize(keys, errors, params)
@keys = keys.reject{|k| params[k].nil? }
@errors = errors
@params = params
end
def as_string
@errors.concat @keys.reject{|k| @params[k].is_a?(String)}.map{|k| "#{k} must be a string"}
return self
end
def as_int
@errors.concat @keys
.reject{|k| @params[k].is_a?(Integer) || @params[k].to_i.to_s == @params[k]}
.map{|k| "#{k} must be an integer"}
return self
end
def with_format(regex)
@errors.concat @keys.reject{|k| @params[k] =~ regex}.map{|k| "#{k} must match: #{regex}"}
return self
end
def one_of(*vals)
@errors.concat @keys.reject{|k| vals.include?(@params[k])}.map{|k| "#{k} must be one of: #{vals.join(", ")}"}
return self
end
def nested(&block)
@errors.concat @keys.map{|k| Validation.new(@params[k]).instance_exec(@params, &block).errors}.flatten
return self
end
def as_array
@errors.concat @keys.reject{|k| @params[k].is_a?(Array)}.map{|k| "#{k} must be an array"}
end
def array_of(&block)
@errors.concat @keys.reject{|k| @params[k].is_a?(Array)}.map{|k| "#{k} must be an array"}
@errors.concat @keys.map{|k| @params[k].map{|h| Validation.new(h).instance_exec(@params, &block).errors}}.flatten
return self
end
def as_date
with_format /\d\d\d\d-\d\d-\d\d/
@errors.concat @keys.map{|k| [k].concat @params[k].split('-').map(&:to_i)}
.reject{|key, year, month, day| year.present? && year > 1000 && year < 3000 && month.present? && month > 0 && month < 13 && day.present? && day > 0 && day < 32}
.map{|k, _,_,_| "#{k} must be a valid date"}
end
def min(n)
@errors.concat @keys.reject{|k| @params[k] >= n}.map{|k| "#{k} must be at least #{n}"}
return self
end
def max(n)
@errors.concat @keys.reject{|k| @params[k] <= n}.map{|k| "#{k} must be less than #{n + 1}"}
return self
end
# TODO min_len, max_len, as_float, as_currency, as_time, as_datetime
# TODO return err resp on unrecognized params
end
end