Pre-fill quantity on part ordering form (#3395)

* Pre-fill quantity on part ordering form

- Adds new API endpoint for requirement data
- Load data on the fly when launching ordering form

* Bump API version

InvenTree/InvenTree/api_version.py

@@ -2,11 +2,15 @@
 
 
 # InvenTree API version
-INVENTREE_API_VERSION = 66
+INVENTREE_API_VERSION = 67
 
 """
 Increment this API version number whenever there is a significant change to the API that any clients need to know about
 
+v67 -> 2022-07-25 : https://github.com/inventree/InvenTree/pull/3395
+    - Adds a 'requirements' endpoint for Part instance
+    - Provides information on outstanding order requirements for a given part
+
 v66 -> 2022-07-24 : https://github.com/inventree/InvenTree/pull/3393
     - Part images can now be downloaded from a remote URL via the API
     - Company images can now be downloaded from a remote URL via the API

InvenTree/part/api.py

@@ -567,6 +567,40 @@ class PartScheduling(RetrieveAPI):
         return Response(schedule)
 
 
+class PartRequirements(RetrieveAPI):
+    """API endpoint detailing 'requirements' information for aa particular part.
+
+    This endpoint returns information on upcoming requirements for:
+
+    - Sales Orders
+    - Build Orders
+    - Total requirements
+
+    As this data is somewhat complex to calculate, is it not included in the default API
+    """
+
+    queryset = Part.objects.all()
+
+    def retrieve(self, request, *args, **kwargs):
+        """Construct a response detailing Part requirements"""
+
+        part = self.get_object()
+
+        data = {
+            "available_stock": part.available_stock,
+            "on_order": part.on_order,
+            "required_build_order_quantity": part.required_build_order_quantity(),
+            "allocated_build_order_quantity": part.build_order_allocation_count(),
+            "required_sales_order_quantity": part.required_sales_order_quantity(),
+            "allocated_sales_order_quantity": part.sales_order_allocation_count(pending=True),
+        }
+
+        data["allocated"] = data["allocated_build_order_quantity"] + data["allocated_sales_order_quantity"]
+        data["required"] = data["required_build_order_quantity"] + data["required_sales_order_quantity"]
+
+        return Response(data)
+
+
 class PartMetadata(RetrieveUpdateAPI):
     """API endpoint for viewing / updating Part metadata."""
 
@@ -1997,6 +2031,8 @@ part_api_urls = [
         # Endpoint for future scheduling information
         re_path(r'^scheduling/', PartScheduling.as_view(), name='api-part-scheduling'),
 
+        re_path(r'^requirements/', PartRequirements.as_view(), name='api-part-requirements'),
+
         # Endpoint for duplicating a BOM for the specific Part
         re_path(r'^bom-copy/', PartCopyBOM.as_view(), name='api-part-bom-copy'),
 

InvenTree/templates/js/translated/order.js

@@ -817,7 +817,7 @@ function orderParts(parts_list, options={}) {
 
         var thumb = thumbnailImage(part.thumbnail || part.image);
 
-        // The "quantity" field should have been provided for each part
+        // Default quantity value
         var quantity = part.quantity || 1;
 
         if (quantity < 0) {
@@ -1017,6 +1017,29 @@ function orderParts(parts_list, options={}) {
                         return '{% trans "No matching purchase orders" %}';
                     }
                 }, null, opts);
+
+                // Request 'requirements' information for each part
+                inventreeGet(`/api/part/${part.pk}/requirements/`, {}, {
+                    success: function(response) {
+                        var required = response.required || 0;
+                        var allocated = response.allocated || 0;
+                        var available = response.available_stock || 0;
+
+                        // Based on what we currently 'have' on hand, what do we need to order?
+                        var deficit = Math.max(required - allocated, 0);
+
+                        if (available < deficit) {
+                            var q = deficit - available;
+
+                            updateFieldValue(
+                                `quantity_${part.pk}`,
+                                q,
+                                {},
+                                opts
+                            );
+                        }
+                    }
+                });
             });
 
             // Add callback for "add to purchase order" button