diff --git a/app/models/team.rb b/app/models/team.rb
index 9238a0f03..a585a5552 100644
--- a/app/models/team.rb
+++ b/app/models/team.rb
@@ -63,7 +63,7 @@ class Team < ActiveRecord::Base
   # -3 == sample_group
   # TODO: use constants
   def import_samples(sheet, mappings, user)
-    errors = []
+    errors = false
     nr_of_added = 0
     total_nr = 0
 
@@ -72,17 +72,17 @@ class Team < ActiveRecord::Base
     sname_index = -1
     stype_index = -1
     sgroup_index = -1
-    mappings.each.with_index do |(k, v), i|
-      if v == "-1"
+    mappings.each.with_index do |(_, v), i|
+      if v == '-1'
         # Fill blank space, so our indices stay the same
         custom_fields << nil
         sname_index = i
-      elsif v == "-2"
+      elsif v == '-2'
         custom_fields << nil
         stype_index = i
-      elsif v == "-3"
+      elsif v == '-3'
         custom_fields << nil
-        sgroup_index =  i
+        sgroup_index = i
       else
         cf = CustomField.find_by_id(v)
 
@@ -93,85 +93,78 @@ class Team < ActiveRecord::Base
     end
 
     # Now we can iterate through sample data and save stuff into db
-    (2..sheet.last_row).each do |i|
-      error = []
-      total_nr += 1
+    transaction do
+      (2..sheet.last_row).each do |i|
+        total_nr += 1
 
-      sample = Sample.new(
-        name: sheet.row(i)[sname_index],
-        team_id: id,
-        user: user
-      )
+        sample = Sample.new(name: sheet.row(i)[sname_index],
+                            team: self,
+                            user: user)
 
-      if sample.save
-        sheet.row(i).each.with_index do |value, index|
-          # We need to have sample saved before messing with custom fields (they
-          # need sample id)
-          if index == stype_index
-            stype = SampleType.where(name: value, team_id: id).take
+        sample.transaction(requires_new: true) do
+          unless sample.save
+            errors = true
+            raise ActiveRecord::Rollback
+          end
 
-            if stype
-              sample.sample_type = stype
-            else
-              sample.create_sample_type(
-                name: value,
-                team_id: id
-              )
-            end
-            sample.save
-          elsif index == sgroup_index
-            sgroup = SampleGroup.where(name: value, team_id: id).take
+          custom_field_values = []
 
-            if sgroup
-              sample.sample_group = sgroup
-            else
-              sample.create_sample_group(
-                name: value,
-                team_id: id
-              )
-            end
-            sample.save
-          elsif value and mappings[index.to_s].strip.present? and index != sname_index
-            if custom_fields[index]
+          sheet.row(i).each.with_index do |value, index|
+            # We need to have sample saved before messing with custom fields
+            # (they need sample id)
+            if index == stype_index
+              stype = SampleType.where(name: value, team: self).take
+
+              if stype
+                sample.sample_type = stype
+              else
+                sample.create_sample_type(name: value, team: self)
+              end
+              unless sample.save
+                errors = true
+                raise ActiveRecord::Rollback
+              end
+            elsif index == sgroup_index
+              sgroup = SampleGroup.where(name: value, team: self).take
+
+              if sgroup
+                sample.sample_group = sgroup
+              else
+                sample.create_sample_group(name: value, team: self)
+              end
+              unless sample.save
+                errors = true
+                raise ActiveRecord::Rollback
+              end
+            elsif value && custom_fields[index]
               # we're working with CustomField
               scf = SampleCustomField.new(
-                sample_id: sample.id,
-                custom_field_id: custom_fields[index].id,
+                sample: sample,
+                custom_field: custom_fields[index],
                 value: value
               )
-
-              if !scf.save
-                error << scf.errors.messages
+              unless scf.valid?
+                errors = true
+                raise ActiveRecord::Rollback
               end
-            else
-              # This custom_field does not exist
-              error << {"#{mappings[index]}": "Does not exists"}
+              custom_field_values << scf
             end
           end
+          if SampleCustomField.import(custom_field_values,
+                                      recursive: true,
+                                      validate: false).failed_instances.any?
+            errors = true
+            raise ActiveRecord::Rollback
+          end
+          nr_of_added += 1
         end
-      else
-        error << sample.errors.messages
-      end
-      if error.present?
-        errors << { "#{i}": error}
-      else
-        nr_of_added += 1
       end
     end
 
-    if errors.count > 0 then
-      return {
-        status: :error,
-        errors: errors,
-        nr_of_added: nr_of_added,
-        total_nr: total_nr
-      }
+    if errors
+      return { status: :error, nr_of_added: nr_of_added, total_nr: total_nr }
     else
-      return {
-        status: :ok,
-        nr_of_added: nr_of_added,
-        total_nr: total_nr
-      }
+      return { status: :ok, nr_of_added: nr_of_added, total_nr: total_nr }
     end
   end