diff --git a/includes/abstracts/abstract-wc-product.php b/includes/abstracts/abstract-wc-product.php
index 173d08c8420..762e7fa6bdd 100644
--- a/includes/abstracts/abstract-wc-product.php
+++ b/includes/abstracts/abstract-wc-product.php
@@ -1973,7 +1973,8 @@ class WC_Product extends WC_Abstract_Legacy_Product {
 	 * @return array
 	 */
 	public function get_files() {
-		$downloadable_files = array_filter( ! empty( $this->get_downloads() ) ? (array) maybe_unserialize( $this->get_downloads() ) : array() );
+		$downloads          = $this->get_downloads();
+		$downloadable_files = array_filter( ! empty( $downloads ) ? (array) maybe_unserialize( $downloads ) : array() );
 		if ( ! empty( $downloadable_files ) ) {
 
 			foreach ( $downloadable_files as $key => $file ) {
diff --git a/includes/api/class-wc-rest-products-controller.php b/includes/api/class-wc-rest-products-controller.php
index 2337af37250..d1587fec9d3 100644
--- a/includes/api/class-wc-rest-products-controller.php
+++ b/includes/api/class-wc-rest-products-controller.php
@@ -469,20 +469,19 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 	 * @return array
 	 */
 	protected function get_product_data( $product ) {
-		$post = get_post( $product->get_id() );
 		$data = array(
 			'id'                    => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(),
-			'name'                  => $product->get_title(),
-			'slug'                  => $post->post_name,
+			'name'                  => $product->get_name(),
+			'slug'                  => $product->get_slug(),
 			'permalink'             => $product->get_permalink(),
-			'date_created'          => wc_rest_prepare_date_response( $post->post_date_gmt ),
-			'date_modified'         => wc_rest_prepare_date_response( $post->post_modified_gmt ),
+			'date_created'          => wc_rest_prepare_date_response( $product->get_date_created() ),
+			'date_modified'         => wc_rest_prepare_date_response( $product->get_date_modified() ),
 			'type'                  => $product->get_type(),
-			'status'                => $post->post_status,
+			'status'                => $product->get_status(),
 			'featured'              => $product->is_featured(),
 			'catalog_visibility'    => $product->get_catalog_visibility(),
-			'description'           => wpautop( do_shortcode( $post->post_content ) ),
-			'short_description'     => apply_filters( 'woocommerce_short_description', $post->post_excerpt ),
+			'description'           => wpautop( do_shortcode( $product->get_description() ) ),
+			'short_description'     => apply_filters( 'woocommerce_short_description', $product->get_short_description() ),
 			'sku'                   => $product->get_sku(),
 			'price'                 => $product->get_price(),
 			'regular_price'         => $product->get_regular_price(),
@@ -520,13 +519,13 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 			'shipping_taxable'      => $product->is_shipping_taxable(),
 			'shipping_class'        => $product->get_shipping_class(),
 			'shipping_class_id'     => (int) $product->get_shipping_class_id(),
-			'reviews_allowed'       => ( 'open' === $post->comment_status ),
+			'reviews_allowed'       => $product->get_reviews_allowed(),
 			'average_rating'        => wc_format_decimal( $product->get_average_rating(), 2 ),
 			'rating_count'          => (int) $product->get_rating_count(),
 			'related_ids'           => array_map( 'absint', array_values( wc_get_related_products( $product->get_id() ) ) ),
 			'upsell_ids'            => array_map( 'absint', $product->get_upsell_ids() ),
 			'cross_sell_ids'        => array_map( 'absint', $product->get_cross_sell_ids() ),
-			'parent_id'             => $product->is_type( 'variation' ) ? $product->parent->id : $post->post_parent,
+			'parent_id'             => $product->get_parent_id(),
 			'purchase_note'         => wpautop( do_shortcode( wp_kses_post( $product->get_purchase_note() ) ) ),
 			'categories'            => $this->get_taxonomy_terms( $product ),
 			'tags'                  => $this->get_taxonomy_terms( $product, 'tag' ),
@@ -866,7 +865,7 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 				}
 
 				if ( isset( $image['position'] ) && 0 === $image['position'] ) {
-					$product->set_thumbnail_id( $attachment_id );
+					$product->set_image_id( $attachment_id );
 				} else {
 					$gallery[] = $attachment_id;
 				}
@@ -886,7 +885,7 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 				$product->set_gallery_image_ids( $gallery );
 			}
 		} else {
-			$product->set_thumbnail_id( '' );
+			$product->set_image_id( '' );
 			$product->set_gallery_image_ids( array() );
 		}
 
@@ -1192,7 +1191,7 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 		}
 
 		// Update parent if grouped so price sorting works and stays in sync with the cheapest child.
-		if ( $product->get_parent_id() > 0 || 'grouped' === $product->get_type() ) {
+		if ( $product->get_parent_id() > 0 || $product->is_type( 'grouped' ) ) {
 
 			$clear_parent_ids = array();
 
@@ -1204,7 +1203,7 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 				$parent->save();
 			}
 
-			if ( 'grouped' === $product->get_type() ) {
+			if ( $product->is_type( 'grouped' ) ) {
 				$clear_parent_ids[] = $product->get_id();
 			}
 
@@ -1265,40 +1264,40 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 				$backorders = $product->get_backorders();
 			}
 
-			if ( 'grouped' === $product->get_type() ) {
+			if ( $product->is_type( 'grouped' ) ) {
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( 'no' );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( $status );
-			} elseif ( 'external' === $product->get_type() ) {
+			} elseif ( $product->is_type( 'external' ) ) {
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( 'no' );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( 'instock' );
 			} elseif ( 'yes' === $manage_stock ) {
 				$product->set_backorders( $backorders );
 
 				// Stock status is always determined by children so sync later.
-				if ( 'variable' !== $product->get_type() ) {
+				if ( ! $product->is_type( 'variable' ) ) {
 					$product->set_stock_status( $stock_status );
 				}
 
 				// Stock quantity.
 				if ( isset( $request['stock_quantity'] ) ) {
-					$product->set_stock( wc_stock_amount( $request['stock_quantity'] ) );
+					$product->set_stock_quantity( wc_stock_amount( $request['stock_quantity'] ) );
 				} elseif ( isset( $request['inventory_delta'] ) ) {
 					$stock_quantity  = wc_stock_amount( $product->get_stock() );
 					$stock_quantity += wc_stock_amount( $request['inventory_delta'] );
-					$product->set_stock( wc_stock_amount( $stock_quantity ) );
+					$product->set_stock_quantity( wc_stock_amount( $stock_quantity ) );
 				}
 			} else {
 				// Don't manage stock.
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( $backorders );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( $stock_status );
 			}
-		} elseif ( 'variable' !== $product->get_type() ) {
+		} elseif ( ! $product->is_type( 'variable' ) ) {
 			$product->set_stock_status( $stock_status );
 		}
 
@@ -1376,7 +1375,7 @@ class WC_REST_Products_Controller extends WC_REST_Posts_Controller {
 		}
 
 		// Product url and button text for external products.
-		if ( 'external' === $product->get_type() ) {
+		if ( $product->is_type( 'external' ) ) {
 			if ( isset( $request['external_url'] ) ) {
 				$product->set_product_url( $request['external_url'] );
 			}
diff --git a/includes/api/legacy/v1/class-wc-api-products.php b/includes/api/legacy/v1/class-wc-api-products.php
index 157481faa1d..a2346572e5a 100644
--- a/includes/api/legacy/v1/class-wc-api-products.php
+++ b/includes/api/legacy/v1/class-wc-api-products.php
@@ -266,12 +266,11 @@ class WC_API_Products extends WC_API_Resource {
 	 * @return array
 	 */
 	private function get_product_data( $product ) {
-		$post = get_post( $product->get_id() );
 		return array(
-			'title'              => $product->get_title(),
-			'id'                 => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(),
-			'created_at'         => $this->server->format_datetime( $post->post_date_gmt ),
-			'updated_at'         => $this->server->format_datetime( $post->post_modified_gmt ),
+			'title'              => $product->get_name(),
+			'id'                 => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(), // @todo variation
+			'created_at'         => $this->server->format_datetime( $product->get_date_created() ),
+			'updated_at'         => $this->server->format_datetime( $product->get_date_modified() ),
 			'type'               => $product->get_type(),
 			'status'             => $product->get_status(),
 			'downloadable'       => $product->is_downloadable(),
@@ -286,7 +285,7 @@ class WC_API_Products extends WC_API_Resource {
 			'tax_status'         => $product->get_tax_status(),
 			'tax_class'          => $product->get_tax_class(),
 			'managing_stock'     => $product->managing_stock(),
-			'stock_quantity'     => (int) $product->get_stock_quantity(),
+			'stock_quantity'     => $product->get_stock_quantity(),
 			'in_stock'           => $product->is_in_stock(),
 			'backorders_allowed' => $product->backorders_allowed(),
 			'backordered'        => $product->is_on_backorder(),
@@ -311,7 +310,7 @@ class WC_API_Products extends WC_API_Resource {
 			'short_description'  => apply_filters( 'woocommerce_short_description', $product->get_short_description() ),
 			'reviews_allowed'    => $product->get_reviews_allowed(),
 			'average_rating'     => wc_format_decimal( $product->get_average_rating(), 2 ),
-			'rating_count'       => (int) $product->get_rating_count(),
+			'rating_count'       => $product->get_rating_count(),
 			'related_ids'        => array_map( 'absint', array_values( wc_get_related_products( $product->get_id() ) ) ),
 			'upsell_ids'         => array_map( 'absint', $product->get_upsell_ids() ),
 			'cross_sell_ids'     => array_map( 'absint', $product->get_cross_sell_ids() ),
@@ -321,11 +320,11 @@ class WC_API_Products extends WC_API_Resource {
 			'featured_src'       => wp_get_attachment_url( get_post_thumbnail_id( $product->is_type( 'variation' ) ? $product->variation_id : $product->get_id() ) ),
 			'attributes'         => $this->get_attributes( $product ),
 			'downloads'          => $this->get_downloads( $product ),
-			'download_limit'     => (int) $product->get_download_limit(),
-			'download_expiry'    => (int) $product->get_download_expiry(),
+			'download_limit'     => $product->get_download_limit(),
+			'download_expiry'    => $product->get_download_expiry(),
 			'download_type'      => 'standard',
 			'purchase_note'      => apply_filters( 'the_content', $product->get_purchase_note() ),
-			'total_sales'        => metadata_exists( 'post', $product->get_id(), 'total_sales' ) ? (int) get_post_meta( $product->get_id(), 'total_sales', true ) : 0,
+			'total_sales'        => $product->get_total_sales(),
 			'variations'         => array(),
 			'parent'             => array(),
 		);
@@ -401,8 +400,8 @@ class WC_API_Products extends WC_API_Resource {
 	 * @return array
 	 */
 	private function get_images( $product ) {
-
-		$images = $attachment_ids = array();
+		$images            = $attachment_ids = array();
+		$product_image     = $product->get_image_id();
 
 		if ( $product->is_type( 'variation' ) ) {
 			// @todo variation
@@ -411,16 +410,16 @@ class WC_API_Products extends WC_API_Resource {
 				// add variation image if set
 				$attachment_ids[] = get_post_thumbnail_id( $product->get_variation_id() );
 
-			} elseif ( ! empty( $product->get_thumbnail_id() ) ) {
+			} elseif ( ! empty( $product_image ) ) {
 
 				// otherwise use the parent product featured image if set
-				$attachment_ids[] = $product->get_thumbnail_id();
+				$attachment_ids[] = $product_image;
 			}
 		} else {
 
 			// Add featured image
-			if ( ! empty( $product->get_thumbnail_id() ) ) {
-				$attachment_ids[] = $product->get_thumbnail_id();
+			if ( ! empty( $product_image ) ) {
+				$attachment_ids[] = $product_image;
 			}
 
 			// add gallery images
diff --git a/includes/api/legacy/v2/class-wc-api-products.php b/includes/api/legacy/v2/class-wc-api-products.php
index 28c96a8e67e..5ea18323b93 100644
--- a/includes/api/legacy/v2/class-wc-api-products.php
+++ b/includes/api/legacy/v2/class-wc-api-products.php
@@ -268,7 +268,7 @@ class WC_API_Products extends WC_API_Resource {
 			$id = $product->get_id();
 
 			// Checks for an error in the product creation
-			if ( ! $id > 0 ) {
+			if ( 0 >= $id ) {
 				throw new WC_API_Exception( 'woocommerce_api_cannot_create_product', $id->get_error_message(), 400 );
 			}
 
@@ -679,12 +679,11 @@ class WC_API_Products extends WC_API_Resource {
 	 */
 	private function get_product_data( $product ) {
 		$prices_precision = wc_get_price_decimals();
-		$post             = get_post( $product->get_id() );
 		return array(
-			'title'              => $product->get_title(),
-			'id'                 => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(),
-			'created_at'         => $this->server->format_datetime( $post->post_date_gmt ),
-			'updated_at'         => $this->server->format_datetime( $post->post_modified_gmt ),
+			'title'              => $product->get_name(),
+			'id'                 => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(), // @todo variation
+			'created_at'         => $this->server->format_datetime( $product->get_date_created() ),
+			'updated_at'         => $this->server->format_datetime( $product->get_date_modified() ),
 			'type'               => $product->get_type(),
 			'status'             => $product->get_status(),
 			'downloadable'       => $product->is_downloadable(),
@@ -699,7 +698,7 @@ class WC_API_Products extends WC_API_Resource {
 			'tax_status'         => $product->get_tax_status(),
 			'tax_class'          => $product->get_tax_class(),
 			'managing_stock'     => $product->managing_stock(),
-			'stock_quantity'     => (int) $product->get_stock_quantity(),
+			'stock_quantity'     => $product->get_stock_quantity(),
 			'in_stock'           => $product->is_in_stock(),
 			'backorders_allowed' => $product->backorders_allowed(),
 			'backordered'        => $product->is_on_backorder(),
@@ -726,7 +725,7 @@ class WC_API_Products extends WC_API_Resource {
 			'short_description'  => apply_filters( 'woocommerce_short_description', $product->get_short_description() ),
 			'reviews_allowed'    => $product->get_reviews_allowed(),
 			'average_rating'     => wc_format_decimal( $product->get_average_rating(), 2 ),
-			'rating_count'       => (int) $product->get_rating_count(),
+			'rating_count'       => $product->get_rating_count(),
 			'related_ids'        => array_map( 'absint', array_values( wc_get_related_products( $product->get_id() ) ) ),
 			'upsell_ids'         => array_map( 'absint', $product->get_upsell_ids() ),
 			'cross_sell_ids'     => array_map( 'absint', $product->get_cross_sell_ids() ),
@@ -734,11 +733,11 @@ class WC_API_Products extends WC_API_Resource {
 			'categories'         => wp_get_post_terms( $product->get_id(), 'product_cat', array( 'fields' => 'names' ) ),
 			'tags'               => wp_get_post_terms( $product->get_id(), 'product_tag', array( 'fields' => 'names' ) ),
 			'images'             => $this->get_images( $product ),
-			'featured_src'       => (string) wp_get_attachment_url( get_post_thumbnail_id( $product->is_type( 'variation' ) ? $product->variation_id : $product->get_id() ) ),
+			'featured_src'       => wp_get_attachment_url( get_post_thumbnail_id( $product->is_type( 'variation' ) ? $product->variation_id : $product->get_id() ) ),
 			'attributes'         => $this->get_attributes( $product ),
 			'downloads'          => $this->get_downloads( $product ),
-			'download_limit'     => (int) $product->get_download_limit(),
-			'download_expiry'    => (int) $product->get_download_expiry(),
+			'download_limit'     => $product->get_download_limit(),
+			'download_expiry'    => $product->get_download_expiry(),
 			'download_type'      => 'standard',
 			'purchase_note'      => wpautop( do_shortcode( wp_kses_post( $product->get_purchase_note() ) ) ),
 			'total_sales'        => $product->get_total_sales(),
@@ -928,7 +927,7 @@ class WC_API_Products extends WC_API_Resource {
 						$attribute_object->set_id( $attribute_id );
 						$attribute_object->set_name( $taxonomy );
 						$attribute_object->set_options( $values );
-						$attribute_object->set_position( isset( $attribute['position'] ) ? (string) absint( $attribute['position'] ) : '0' );
+						$attribute_object->set_position( isset( $attribute['position'] ) ? absint( $attribute['position'] ) : 0 );
 						$attribute_object->set_visible( ( isset( $attribute['visible'] ) && $attribute['visible'] ) ? 1 : 0 );
 						$attribute_object->set_variation( ( isset( $attribute['variation'] ) && $attribute['variation'] ) ? 1 : 0 );
 						$attributes[] = $attribute_object;
@@ -947,7 +946,7 @@ class WC_API_Products extends WC_API_Resource {
 					$attribute_object = new WC_Product_Attribute();
 					$attribute_object->set_name( $attribute['name'] );
 					$attribute_object->set_options( $values );
-					$attribute_object->set_position( isset( $attribute['position'] ) ? (string) absint( $attribute['position'] ) : '0' );
+					$attribute_object->set_position( isset( $attribute['position'] ) ? absint( $attribute['position'] ) : 0 );
 					$attribute_object->set_visible( ( isset( $attribute['visible'] ) && $attribute['visible'] ) ? 1 : 0 );
 					$attribute_object->set_variation( ( isset( $attribute['variation'] ) && $attribute['variation'] ) ? 1 : 0 );
 					$attributes[] = $attribute_object;
@@ -1020,7 +1019,7 @@ class WC_API_Products extends WC_API_Resource {
 		}
 
 		// Update parent if grouped so price sorting works and stays in sync with the cheapest child
-		if ( $product->get_parent_id() > 0 || 'grouped' === $product->get_type() ) {
+		if ( $product->get_parent_id() > 0 || $product->is_type( 'grouped' ) ) {
 			if ( $product->get_parent_id() > 0 ) {
 				$parent = wc_get_product( $product->get_parent_id() );
 				$children = $parent->get_children();
@@ -1068,36 +1067,36 @@ class WC_API_Products extends WC_API_Resource {
 				$backorders = $product->get_backorders();
 			}
 
-			if ( 'grouped' == $product->get_type() ) {
+			if ( $product->is_type( 'grouped' ) ) {
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( 'no' );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( $stock_status );
-			} elseif ( 'external' == $product->get_type() ) {
+			} elseif ( $product->is_type( 'external' ) ) {
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( 'no' );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( 'instock' );
 			} elseif ( 'yes' == $managing_stock ) {
 				$product->set_backorders( $backorders );
 
 				// Stock status is always determined by children so sync later.
-				if ( 'variable' !== $product->get_type() ) {
+				if ( ! $product->is_type( 'variable' ) ) {
 					$product->set_stock_status( $stock_status );
 				}
 
 				// Stock quantity
 				if ( isset( $data['stock_quantity'] ) ) {
-					$product->set_stock( wc_stock_amount( $data['stock_quantity'] ) );
+					$product->set_stock_quantity( wc_stock_amount( $data['stock_quantity'] ) );
 				}
 			} else {
 				// Don't manage stock.
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( $backorders );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( $stock_status );
 			}
-		} elseif ( 'variable' !== $product->get_type() ) {
+		} elseif ( ! $product->is_type( 'variable' ) ) {
 			$product->set_stock_status( $stock_status );
 		}
 
@@ -1177,7 +1176,7 @@ class WC_API_Products extends WC_API_Resource {
 		}
 
 		// Product url
-		if ( 'external' === $product->get_type() ) {
+		if ( $product->is_type( 'external' ) ) {
 			if ( isset( $data['product_url'] ) ) {
 				$product->set_product_url( $data['product_url'] );
 			}
@@ -1639,25 +1638,25 @@ class WC_API_Products extends WC_API_Resource {
 	 * @return array
 	 */
 	private function get_images( $product ) {
-
-		$images = $attachment_ids = array();
+		$images        = $attachment_ids = array();
+		$product_image = $product->get_image_id();
 
 		if ( $product->is_type( 'variation' ) ) {
-
+			// @todo variation
 			if ( has_post_thumbnail( $product->get_variation_id() ) ) {
 
 				// Add variation image if set
 				$attachment_ids[] = get_post_thumbnail_id( $product->get_variation_id() );
 
-			} elseif ( ! empty( $product->get_thumbnail_id() ) ) {
+			} elseif ( ! empty( $product_image ) ) {
 				// Otherwise use the parent product featured image if set
-				$attachment_ids[] = $product->get_thumbnail_id();
+				$attachment_ids[] = $product_image;
 			}
 		} else {
 
 			// Add featured image
-			if ( ! empty( $product->get_thumbnail_id() ) ) {
-				$attachment_ids[] = $product->get_thumbnail_id();
+			if ( ! empty( $product_image ) ) {
+				$attachment_ids[] = $product_image;
 			}
 
 			// Add gallery images
@@ -1733,7 +1732,7 @@ class WC_API_Products extends WC_API_Resource {
 						$attachment_id = $this->set_product_image_as_attachment( $upload, $product->get_id() );
 					}
 
-					$product->set_thumbnail_id( $attachment_id );
+					$product->set_image_id( $attachment_id );
 				} else {
 					$attachment_id = isset( $image['id'] ) ? absint( $image['id'] ) : 0;
 
@@ -1752,11 +1751,11 @@ class WC_API_Products extends WC_API_Resource {
 			}
 
 			if ( ! empty( $gallery ) ) {
-				$product->set_gallery_attachment_ids( $gallery );
+				$product->set_gallery_image_ids( $gallery );
 			}
 		} else {
-			$product->set_thumbnail_id( '' );
-			$product->set_gallery_attachment_ids( array() );
+			$product->set_image_id( '' );
+			$product->set_gallery_image_ids( array() );
 		}
 
 		return $product;
diff --git a/includes/api/legacy/v3/class-wc-api-products.php b/includes/api/legacy/v3/class-wc-api-products.php
index e3464114a39..33ac4dac94e 100644
--- a/includes/api/legacy/v3/class-wc-api-products.php
+++ b/includes/api/legacy/v3/class-wc-api-products.php
@@ -207,9 +207,12 @@ class WC_API_Products extends WC_API_Resource {
 			$product_data['grouped_products'] = $this->get_grouped_products_data( $product );
 		}
 
-		if ( $product->is_type( 'simple' ) && ! empty( $product->get_parent_id() ) ) {
-			$_product = wc_get_product( $product->get_parent_id() );
-			$product_data['parent'] = $this->get_product_data( $_product );
+		if ( $product->is_type( 'simple' ) ) {
+			$parent_id = $product->get_parent_id();
+			if ( ! empty( $parent_id ) ) {
+				$_product               = wc_get_product( $parent_id );
+				$product_data['parent'] = $this->get_product_data( $_product );
+			}
 		}
 
 		return array( 'product' => apply_filters( 'woocommerce_api_product_response', $product_data, $product, $fields, $this->server ) );
@@ -319,7 +322,7 @@ class WC_API_Products extends WC_API_Resource {
 			$id = $product->get_id();
 
 			// Checks for an error in the product creation.
-			if ( ! $id > 0 ) {
+			if ( 0 >= $id ) {
 				throw new WC_API_Exception( 'woocommerce_api_cannot_create_product', $id->get_error_message(), 400 );
 			}
 
@@ -1121,12 +1124,11 @@ class WC_API_Products extends WC_API_Resource {
 	 * @return WC_Product
 	 */
 	private function get_product_data( $product ) {
-		$post = get_post( $product->get_id() );
 		return array(
-			'title'              => $product->get_title(),
-			'id'                 => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(),
-			'created_at'         => $this->server->format_datetime( $post->post_date_gmt ),
-			'updated_at'         => $this->server->format_datetime( $post->post_modified_gmt ),
+			'title'              => $product->get_name(),
+			'id'                 => (int) $product->is_type( 'variation' ) ? $product->get_variation_id() : $product->get_id(), // @todo variation
+			'created_at'         => $this->server->format_datetime( $product->get_date_created() ),
+			'updated_at'         => $this->server->format_datetime( $product->get_date_modified() ),
 			'type'               => $product->get_type(),
 			'status'             => $product->get_status(),
 			'downloadable'       => $product->is_downloadable(),
@@ -1166,9 +1168,9 @@ class WC_API_Products extends WC_API_Resource {
 			'shipping_class_id'  => ( 0 !== $product->get_shipping_class_id() ) ? $product->get_shipping_class_id() : null,
 			'description'        => wpautop( do_shortcode( $product->get_description() ) ),
 			'short_description'  => apply_filters( 'woocommerce_short_description', $product->get_short_description() ),
-			'reviews_allowed'    => ( 'open' === $product->get_post_data()->comment_status ),
+			'reviews_allowed'    => $product->get_reviews_allowed(),
 			'average_rating'     => wc_format_decimal( $product->get_average_rating(), 2 ),
-			'rating_count'       => (int) $product->get_rating_count(),
+			'rating_count'       => $product->get_rating_count(),
 			'related_ids'        => array_map( 'absint', array_values( wc_get_related_products( $product->get_id() ) ) ),
 			'upsell_ids'         => array_map( 'absint', $product->get_upsell_ids() ),
 			'cross_sell_ids'     => array_map( 'absint', $product->get_cross_sell_ids() ),
@@ -1176,11 +1178,11 @@ class WC_API_Products extends WC_API_Resource {
 			'categories'         => wp_get_post_terms( $product->get_id(), 'product_cat', array( 'fields' => 'names' ) ),
 			'tags'               => wp_get_post_terms( $product->get_id(), 'product_tag', array( 'fields' => 'names' ) ),
 			'images'             => $this->get_images( $product ),
-			'featured_src'       => (string) wp_get_attachment_url( get_post_thumbnail_id( $product->is_type( 'variation' ) ? $product->variation_id : $product->get_id() ) ),
+			'featured_src'       => wp_get_attachment_url( get_post_thumbnail_id( $product->is_type( 'variation' ) ? $product->variation_id : $product->get_id() ) ),
 			'attributes'         => $this->get_attributes( $product ),
 			'downloads'          => $this->get_downloads( $product ),
-			'download_limit'     => (int) $product->get_download_limit(),
-			'download_expiry'    => (int) $product->get_download_expiry(),
+			'download_limit'     => $product->get_download_limit(),
+			'download_expiry'    => $product->get_download_expiry(),
 			'download_type'      => 'standard',
 			'purchase_note'      => wpautop( do_shortcode( wp_kses_post( $product->get_purchase_note() ) ) ),
 			'total_sales'        => $product->get_total_sales(),
@@ -1415,7 +1417,7 @@ class WC_API_Products extends WC_API_Resource {
 						$attribute_object->set_id( $attribute_id );
 						$attribute_object->set_name( $taxonomy );
 						$attribute_object->set_options( $values );
-						$attribute_object->set_position( isset( $attribute['position'] ) ? (string) absint( $attribute['position'] ) : '0' );
+						$attribute_object->set_position( isset( $attribute['position'] ) ? absint( $attribute['position'] ) : 0 );
 						$attribute_object->set_visible( ( isset( $attribute['visible'] ) && $attribute['visible'] ) ? 1 : 0 );
 						$attribute_object->set_variation( ( isset( $attribute['variation'] ) && $attribute['variation'] ) ? 1 : 0 );
 						$attributes[] = $attribute_object;
@@ -1434,7 +1436,7 @@ class WC_API_Products extends WC_API_Resource {
 					$attribute_object = new WC_Product_Attribute();
 					$attribute_object->set_name( $attribute['name'] );
 					$attribute_object->set_options( $values );
-					$attribute_object->set_position( isset( $attribute['position'] ) ? (string) absint( $attribute['position'] ) : '0' );
+					$attribute_object->set_position( isset( $attribute['position'] ) ? absint( $attribute['position'] ) : 0 );
 					$attribute_object->set_visible( ( isset( $attribute['visible'] ) && $attribute['visible'] ) ? 1 : 0 );
 					$attribute_object->set_variation( ( isset( $attribute['variation'] ) && $attribute['variation'] ) ? 1 : 0 );
 					$attributes[] = $attribute_object;
@@ -1506,7 +1508,7 @@ class WC_API_Products extends WC_API_Resource {
 		}
 
 		// Update parent if grouped so price sorting works and stays in sync with the cheapest child.
-		if ( $product->get_parent_id() > 0 || 'grouped' === $product->get_type() ) {
+		if ( $product->get_parent_id() > 0 || $product->is_type( 'grouped' ) ) {
 			if ( $product->get_parent_id() > 0 ) {
 				$parent = wc_get_product( $product->get_parent_id() );
 				$children = $parent->get_children();
@@ -1554,40 +1556,40 @@ class WC_API_Products extends WC_API_Resource {
 				$backorders = $product->get_backorders();
 			}
 
-			if ( 'grouped' == $product->get_type() ) {
+			if ( $product->is_type( 'grouped' ) ) {
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( 'no' );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( $stock_status );
-			} elseif ( 'external' == $product->get_type() ) {
+			} elseif ( $product->is_type( 'external' ) ) {
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( 'no' );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( 'instock' );
 			} elseif ( 'yes' == $managing_stock ) {
 				$product->set_backorders( $backorders );
 
 				// Stock status is always determined by children so sync later.
-				if ( 'variable' !== $product->get_type() ) {
+				if ( ! $product->is_type( 'variable' ) ) {
 					$product->set_stock_status( $stock_status );
 				}
 
 				// Stock quantity.
 				if ( isset( $data['stock_quantity'] ) ) {
-					$product->set_stock( wc_stock_amount( $data['stock_quantity'] ) );
+					$product->set_stock_quantity( wc_stock_amount( $data['stock_quantity'] ) );
 				} else if ( isset( $data['inventory_delta'] ) ) {
 					$stock_quantity  = wc_stock_amount( $product->get_stock() );
 					$stock_quantity += wc_stock_amount( $data['inventory_delta'] );
-					$product->set_stock( wc_stock_amount( $stock_quantity ) );
+					$product->set_stock_quantity( wc_stock_amount( $stock_quantity ) );
 				}
 			} else {
 				// Don't manage stock.
 				$product->set_manage_stock( 'no' );
 				$product->set_backorders( $backorders );
-				$product->set_stock( '' );
+				$product->set_stock_quantity( '' );
 				$product->set_stock_status( $stock_status );
 			}
-		} elseif ( 'variable' !== $product->get_type() ) {
+		} elseif ( ! $product->is_type( 'variable' ) ) {
 			$product->set_stock_status( $stock_status );
 		}
 
@@ -1667,7 +1669,7 @@ class WC_API_Products extends WC_API_Resource {
 		}
 
 		// Product url.
-		if ( 'external' === $product->get_type() ) {
+		if ( $product->is_type( 'external' ) ) {
 			if ( isset( $data['product_url'] ) ) {
 				$product->set_product_url( $data['product_url'] );
 			}
@@ -2161,8 +2163,8 @@ class WC_API_Products extends WC_API_Resource {
 	 * @return array
 	 */
 	private function get_images( $product ) {
-
-		$images = $attachment_ids = array();
+		$images        = $attachment_ids = array();
+		$product_image = $product->get_image_id();
 
 		if ( $product->is_type( 'variation' ) ) {
 			// @todo variation
@@ -2171,15 +2173,15 @@ class WC_API_Products extends WC_API_Resource {
 				// Add variation image if set
 				$attachment_ids[] = get_post_thumbnail_id( $product->get_variation_id() );
 
-			} elseif ( ! empty( $product->get_thumbnail_id() ) ) {
+			} elseif ( ! empty( $product_image ) ) {
 				// Otherwise use the parent product featured image if set
-				$attachment_ids[] = $product->get_thumbnail_id();
+				$attachment_ids[] = $product_image;
 			}
 		} else {
 
 			// Add featured image
-			if ( ! empty( $product->get_thumbnail_id() ) ) {
-				$attachment_ids[] = $product->get_thumbnail_id();
+			if ( ! empty( $product_image ) ) {
+				$attachment_ids[] = $product_image;
 			}
 
 			// Add gallery images
@@ -2256,7 +2258,7 @@ class WC_API_Products extends WC_API_Resource {
 						$attachment_id = $this->set_product_image_as_attachment( $upload, $product->get_id() );
 					}
 
-					$product->set_thumbnail_id( $attachment_id );
+					$product->set_image_id( $attachment_id );
 				} else {
 					$attachment_id = isset( $image['id'] ) ? absint( $image['id'] ) : 0;
 
@@ -2285,11 +2287,11 @@ class WC_API_Products extends WC_API_Resource {
 			}
 
 			if ( ! empty( $gallery ) ) {
-				$product->set_gallery_attachment_ids( $gallery );
+				$product->set_gallery_image_ids( $gallery );
 			}
 		} else {
-			$product->set_thumbnail_id( '' );
-			$product->set_gallery_attachment_ids( array() );
+			$product->set_image_id( '' );
+			$product->set_gallery_image_ids( array() );
 		}
 
 		return $product;
diff --git a/includes/class-wc-product-grouped.php b/includes/class-wc-product-grouped.php
index 85c8003c1c7..2f462e9cdb9 100644
--- a/includes/class-wc-product-grouped.php
+++ b/includes/class-wc-product-grouped.php
@@ -178,7 +178,9 @@ class WC_Product_Grouped extends WC_Product {
 			$child_prices = array();
 			foreach ( $this->get_children() as $child_id ) {
 				$child = wc_get_product( $child_id );
-				$child_prices[] = $child->get_price();
+				if ( $child ) {
+					$child_prices[] = $child->get_price();
+				}
 			}
 			$child_prices = array_filter( $child_prices );
 			delete_post_meta( $this->get_id(), '_price' );