added one more spec, example, new proc syntax

Author: Fivell

README.md

@@ -94,7 +94,7 @@ And then execute:
     ActiveAdmin.register Post  do
        active_admin_import  validate: false,
                             csv_options: {col_sep: ";" },
-                            before_import: proc{ Post.delete_all},
+                            before_import: ->(importer){ Post.delete_all },
                             batch_size: 1000
 
 
@@ -111,14 +111,14 @@ And then execute:
         active_admin_import validate: false,
             csv_options: {col_sep: ";" },
             resource_class: ImportedPost ,  # we import data into another resource
-            before_import: proc{ ImportedPost.delete_all },
-            after_import: proc{
+            before_import: ->(importer){  ImportedPost.delete_all },
+            after_import:  ->(importer){
                 Post.transaction do
                     Post.delete_all
                     Post.connection.execute("INSERT INTO posts (SELECT * FROM imported_posts)")
                 end
             },
-            back: proc { config.namespace.resource_for(Post).route_collection_path } # redirect to post index
+            back: -> {  config.namespace.resource_for(Post).route_collection_path } # redirect to post index
     end
 ```
 
@@ -167,7 +167,7 @@ And then execute:
 ```ruby
     ActiveAdmin.register Post  do
         active_admin_import validate: true,
-        before_batch_import: proc { |import|
+        before_batch_import: ->(importer) {
            import.file #current file used
            import.resource #ActiveRecord class to import to
            import.options # options
@@ -176,13 +176,28 @@ And then execute:
            import.csv_lines #lines to import
            import.model #template_object instance
         },
-        after_batch_import: proc{ |import|
+        after_batch_import: ->(importer) {
            #the same
         }
     end
 ```    
 
-#### Example7 change csv values before import (find each 'Author name' column and replace it with authors_id before insert )
+#### Example7 update by id emulation
+
+     ```ruby
+         ActiveAdmin.register Post  do
+            active_admin_import({
+                before_batch_import: ->(importer) {
+                    Post.where(id: importer.values_at('id')).delete_all
+                }
+            })
+         end
+
+      ```
+
+
+
+#### Example8 change csv values before import (find each 'Author name' column and replace it with authors_id before insert )
 
    ```ruby
      ActiveAdmin.register Post  do
@@ -199,9 +214,9 @@ And then execute:
   ```
 
 
-#### Example8 dynamic CSV options, template overriding
+#### Example9 dynamic CSV options, template overriding
 
- -  put overrided template to ```app/views/import.html.erb```
+ -  put overridden template to ```app/views/import.html.erb```
 
 ```erb
 

lib/active_admin_import/dsl.rb

@@ -24,7 +24,7 @@ module DSL
     #
 
 
-    DEFAULT_RESULT_PROC = proc do |result, options|
+    DEFAULT_RESULT_PROC =  ->(result, options) do
 
       model_name = options[:resource_label].downcase
       plural_model_name = options[:plural_resource_label].downcase

lib/active_admin_import/model.rb

@@ -10,14 +10,14 @@ class Model
     include ActiveModel::Validations::Callbacks
 
     validates :file, presence: {
-      message: proc { I18n.t("active_admin_import.no_file_error") }
-    }, unless: proc { |me| me.new_record? }
+      message: ->(*_){ I18n.t("active_admin_import.no_file_error") }
+    }, unless: ->(me){ me.new_record? }
 
-    validate :correct_content_type, if: proc { |me| me.file.present? }
-    validate :file_contents_present, if: proc { |me| me.file.present? }
+    validate :correct_content_type, if: ->(me) { me.file.present? }
+    validate :file_contents_present, if: ->(me) { me.file.present? }
 
-    before_validation :uncompress_file, if: proc { |me| me.archive? && me.allow_archive? }
-    before_validation :encode_file, if: proc { |me| me.force_encoding? && me.file.present? }
+    before_validation :unzip_file, if: ->(me) { me.archive? && me.allow_archive? }
+    before_validation :encode_file, if: ->(me) { me.force_encoding? && me.file.present? }
 
     attr_reader :attributes
 
@@ -40,7 +40,13 @@ def read_attribute_for_validation(key)
     end
 
     def default_attributes
-      {hint: '', file: nil, csv_headers: [], allow_archive: true, force_encoding: 'UTF-8'}
+      {
+        allow_archive: true,
+        csv_headers: [],
+        file: nil,
+        force_encoding: "UTF-8",
+        hint: ""
+      }
     end
 
     def allow_archive?
@@ -82,7 +88,7 @@ def encode_file
       end
     end
 
-    def uncompress_file
+    def unzip_file
       Zip::File.open(file_path) do |zip_file|
         self.file = Tempfile.new('active-admin-import-unzipped')
         data = zip_file.entries.select { |f| f.file? }.first.get_input_stream.read

spec/fixtures/files/authors_with_ids.csv

@@ -0,0 +1,3 @@
+Id,Name,Last name,Birthday
+1,John,Doe,1986-05-01
+2,Jane,Roe,1988-11-16

spec/import_spec.rb

@@ -46,24 +46,24 @@ def upload_file!(name, ext='csv')
 
   context "posts index" do
     before do
-        Author.create!(name: 'John', last_name: 'Doe')
-        Author.create!(name: 'Jane', last_name: 'Roe')
-        add_post_resource({
-          validate: true,
-          headers_rewrites: {
-              :'Author Name' => :author_id
-          },
-          before_batch_import: ->(importer) do
-            authors_names = importer.values_at(:author_id)
-            # replacing author name with author id
-            authors   = Author.where(name: authors_names).pluck(:name, :id)
-            #{"Jane" => 2, "John" => 1}
-            options = Hash[*authors.flatten]
-            importer.batch_replace(:author_id, options)
-          end
-        })
-        visit '/admin/posts/import'
-        upload_file!(:posts)
+      Author.create!(name: "John", last_name: "Doe")
+      Author.create!(name: "Jane", last_name: "Roe")
+      add_post_resource({
+        validate: true,
+        headers_rewrites: {
+          :'Author Name' => :author_id
+        },
+        before_batch_import: ->(importer) do
+          authors_names = importer.values_at(:author_id)
+          # replacing author name with author id
+          authors   = Author.where(name: authors_names).pluck(:name, :id)
+          #{"Jane" => 2, "John" => 1}
+          options = Hash[*authors.flatten]
+          importer.batch_replace(:author_id, options)
+        end
+      })
+      visit "/admin/posts/import"
+      upload_file!(:posts)
     end
 
     it "should resolve author_id by author name" do
@@ -114,6 +114,37 @@ def upload_file!(name, ext='csv')
 
   end
 
+  context "authors already exist" do
+    before do
+      Author.create!(id: 1, name: "Jane", last_name: "Roe")
+      Author.create!(id: 2, name: "John", last_name: "Doe")
+    end
+
+    context "having authors with the same Id" do
+      before do
+        add_author_resource({
+          before_batch_import: ->(importer) do
+            Author.where(id: importer.values_at("id")).delete_all
+          end
+        })
+        visit "/admin/authors/import"
+        upload_file!(:authors_with_ids)
+      end
+
+      it "should replace authors" do
+        expect(page).to have_content "Successfully imported 2 authors"
+        expect(Author.count).to eq(2)
+      end
+
+      it "should replace authors by id"  do
+        expect(Author.find(1).name).to eq("John")
+        expect(Author.find(2).name).to eq("Jane")
+      end
+
+    end
+
+  end
+
   context "with valid options" do
 
     let(:options) { {} }
@@ -322,10 +353,10 @@ def upload_file!(name, ext='csv')
     context "with callback procs options" do
       let(:options) do
         {
-          before_import: proc { |_| },
-          after_import: proc { |_| },
-          before_batch_import: proc { |_| },
-          after_batch_import: proc { |_| }
+          before_import: ->(_) { true },
+          after_import: ->(_) { true },
+          before_batch_import: ->(_) { true },
+          after_batch_import: ->(_) { true }
         }
       end