How to refactor this importer to handle validation errors?

Question

This is my importer to database from excel file. I would like to handle situations when any error raise. To not breaks whole import when one errors occurs.

For example when there is duplicated record and I have uniqueness validations. I would like to store this row id in errors table and inform about that at the end.

class DDImporter
 attr_accessor :file
 def initialize(path)
 @path = path 
 end
 def open
 @file = Roo::Excelx.new(@path)
 end
 def sheets
 @file.sheets
 end
 def extract_sheets
 sheets.each do |sheet|
 unless sheet == ("risks" || "allergies_symptoms")
 extract sheet
 end
 end
 end
 def extract sheet_name
 @file.default_sheet = sheet_name
 header = file.row 1
 2.upto(file.last_row) do |i|
 row = Hash[[header, file.row(i)].transpose]
 # row.delete "id"
 object = sheet_name.classify.constantize
 object.create!(row)
 end
 end
end

Answer 1

It can be as simple as :

 def initialize(path)
 @path = path 
 @imported = []
 @errors = []
 end
 def extract sheet_name
 @file.default_sheet = sheet_name
 header = file.row 1
 2.upto(file.last_row) do |i|
 row = Hash[[header, file.row(i)].transpose]
 # row.delete "id"
 model = sheet_name.classify.constantize
 # this is the part that gets the job done.
 object = model.new(row)
 if object.save
 @imported << object
 else
 @rejected << object
 end
 end
 end

... this way you can iterate through @imported or @rejected at the end of the import process (to display errors, or perform additional tasks).

This code can also easily be adapted to only catch exceptions :

 def extract sheet_name
 @file.default_sheet = sheet_name
 header = file.row 1
 2.upto(file.last_row) do |i|
 row = Hash[[header, file.row(i)].transpose]
 # row.delete "id"
 object = sheet_name.classify.constantize
 object.create!(row)
 end
 rescue ActiveRecord::RecordNotUnique, ActiveRecord::RecordInvalid => error
 # rejected record for these errors can be accessed with :
 error.record
 # to resume processing, just :
 error.continue
 end