diff --git a/Gemfile b/Gemfile
index d52745d..0c42c44 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,7 +1,8 @@
 gem 'awesome_nested_set'
 
 group :development do
-  gem "web-console"
+  gem 'web-console'
+  gem 'active_record_query_trace'
 end
 
 group :development, :test do
diff --git a/app/controllers/ingredients_controller.rb b/app/controllers/ingredients_controller.rb
index ce43d42..fac62f7 100644
--- a/app/controllers/ingredients_controller.rb
+++ b/app/controllers/ingredients_controller.rb
@@ -9,7 +9,7 @@ class IngredientsController < ApplicationController
     @ingredient = Ingredient.new(project: @project)
     # passing attr for after_initialize
     @ingredient.nutrients.new(ingredient: @ingredient)
-    @ingredients = @project.ingredients
+    @ingredients = @project.ingredients.includes(:ref_unit)
   end
 
   def create
@@ -18,7 +18,7 @@ class IngredientsController < ApplicationController
       flash[:notice] = 'Created new ingredient'
       redirect_to project_ingredients_url(@project)
     else
-      @ingredients = @project.ingredients
+      @ingredients = @project.ingredients.includes(:ref_unit)
       render :index
     end
   end
@@ -37,7 +37,7 @@ class IngredientsController < ApplicationController
     if params.has_key?(:file)
       quantities = @project.quantities.map { |q| [q.name, q] }.to_h
       units = @project.units.map { |u| [u.shortname, u] }.to_h
-      ingredients = []
+      ingredients_params = []
       column_units = {}
 
       CSV.foreach(params[:file].path, headers: true).with_index(2) do |row, line|
@@ -45,7 +45,7 @@ class IngredientsController < ApplicationController
         unless r.has_key?('Name')
           warnings << "Line 1: required 'Name' column is missing" if line == 2
         end
-        i = {
+        i_params = {
           name: r.delete('Name'),
           ref_amount: 100.0,
           ref_unit: units['g'],
@@ -88,25 +88,34 @@ class IngredientsController < ApplicationController
 
           next if quantities[quantity].blank?
           if quantity == 'Reference'
-            i.update({
+            i_params.update({
               ref_amount: amount.to_d,
               ref_unit: unit
             })
           else
-            i[:nutrients_attributes] << {
+            i_params[:nutrients_attributes] << {
               quantity: quantities[quantity],
               amount: amount.to_d,
               unit: unit
             }
           end
         end
-        ingredients << i
+
+        ingredients_params << i_params
       end
     else
       warnings << 'No file selected'
     end
 
-    if warnings.present?
+    if warnings.empty?
+      ingredients = @project.ingredients.create(ingredients_params)
+      flash[:notice] = "Imported #{ingredients.map(&:persisted?).count(true)} out of" \
+        " #{ingredients_params.length} ingredients"
+      skipped = ingredients.select { |i| !i.persisted? }
+      skipped_desc = skipped.map { |i| "#{i.name} - #{i.errors.full_messages.join(', ')}" }
+      flash[:warning] = "Ingredients skipped due to errors:<br>" \
+        " #{skipped_desc.join('<br>').truncate(1024)}"
+    else
       warnings.unshift("Problems encountered during import - fix and try again:")
       flash[:warning] = warnings.join("<br>").truncate(1024, omission: '...(and other)')
     end
diff --git a/app/models/ingredient.rb b/app/models/ingredient.rb
index d65b3da..0a25f40 100644
--- a/app/models/ingredient.rb
+++ b/app/models/ingredient.rb
@@ -4,26 +4,24 @@ class Ingredient < ActiveRecord::Base
     meat: 1
   }
 
-  belongs_to :project
-  belongs_to :ref_unit, class_name: 'Unit'
+  belongs_to :project, required: true
+  belongs_to :ref_unit, class_name: 'Unit', required: true
 
-  has_many :nutrients, inverse_of: :ingredient, dependent: :destroy
+  has_many :nutrients, inverse_of: :ingredient, dependent: :destroy, validate: true
+  validates :nutrients, presence: true
   accepts_nested_attributes_for :nutrients, allow_destroy: true, reject_if: proc { |attrs|
     attrs['quantity_id'].blank? && attrs['amount'].blank?
   }
-  validates_associated :nutrients
   # Nutrient quantity_id uniqueness check for nested attributes
-  validate on: :create do
+  validate do
     quantities = self.nutrients.map { |n| n.quantity_id }
     if quantities.length != quantities.uniq.length
       errors.add(:nutrients, :duplicated_quantity)
     end
   end
 
-  validates :project, associated: true
   validates :name, presence: true, uniqueness: {scope: :project_id}
   validates :ref_amount, numericality: {greater_than: 0}
-  validates :ref_unit, presence: true, associated: true
   validates :group, inclusion: {in: groups.keys}
 
   after_initialize do
@@ -32,6 +30,7 @@ class Ingredient < ActiveRecord::Base
       units = self.project.units
       self.ref_unit ||= units.find_by(shortname: 'g') || units.first
       self.group ||= :other
+      self.hidden = false if self.hidden.nil?
     end
   end
 
diff --git a/app/models/nutrient.rb b/app/models/nutrient.rb
index df60400..1abc0b1 100644
--- a/app/models/nutrient.rb
+++ b/app/models/nutrient.rb
@@ -1,13 +1,10 @@
 class Nutrient < ActiveRecord::Base
-  belongs_to :ingredient, inverse_of: :nutrients
-  belongs_to :quantity
-  belongs_to :unit
+  belongs_to :ingredient, inverse_of: :nutrients, required: true
+  belongs_to :quantity, required: true
+  belongs_to :unit, required: true
 
-  # disabled to avoid loop with Ingredient 'validates_associated :nutrients'
-  #validates :ingredient, presence: true, associated: true
-  validates :quantity, presence: true, associated: true, uniqueness: {scope: :ingredient_id}
-  validates :amount, numericality: {greater_than: 0}
-  validates :unit, presence: true, associated: true
+  validates :quantity, uniqueness: {scope: :ingredient_id}
+  validates :amount, numericality: {greater_thani_or_equal_to: 0.0}
 
   after_initialize do
     if new_record?
diff --git a/app/models/quantity.rb b/app/models/quantity.rb
index 3dedc3f..c065821 100644
--- a/app/models/quantity.rb
+++ b/app/models/quantity.rb
@@ -1,18 +1,15 @@
 class Quantity < ActiveRecord::Base
-  acts_as_nested_set dependent: :nullify, scope: :project
-
   enum domain: {
     diet: 0,
     measurement: 1,
     exercise: 2
   }
 
-  belongs_to :project
+  acts_as_nested_set dependent: :nullify, scope: :project
+  belongs_to :project, required: false
 
-  validates :project, associated: true
   validates :name, presence: true, uniqueness: {scope: :project_id}
   validates :domain, inclusion: {in: domains.keys}
-  validates :parent, associated: true
   validate if: -> { parent.present? } do
     errors.add(:parent, :parent_domain_mismatch) unless domain == parent.domain
   end
diff --git a/app/models/unit.rb b/app/models/unit.rb
index c446468..7aeff43 100644
--- a/app/models/unit.rb
+++ b/app/models/unit.rb
@@ -1,6 +1,5 @@
 class Unit < ActiveRecord::Base
-  belongs_to :project
+  belongs_to :project, required: true
 
-  validates :project, associated: true
   validates :shortname, presence: true, uniqueness: {scope: :project_id}
 end