From f865573e487029cf8e5658c9b2c855e2e8b77f1b Mon Sep 17 00:00:00 2001
From: Oliver Walters <oliver.henry.walters@gmail.com>
Date: Tue, 11 Feb 2020 22:32:36 +1100
Subject: [PATCH] Implement cascading export of BOM

---
 InvenTree/part/admin.py | 10 ++++++----
 InvenTree/part/bom.py   | 33 ++++++++++++++++++++++++++++++---
 InvenTree/part/views.py |  6 ++++--
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/InvenTree/part/admin.py b/InvenTree/part/admin.py
index 20ad569a12..6f9d2369e5 100644
--- a/InvenTree/part/admin.py
+++ b/InvenTree/part/admin.py
@@ -129,15 +129,17 @@ class PartStarAdmin(admin.ModelAdmin):
 class BomItemResource(ModelResource):
     """ Class for managing BomItem data import/export """
 
+    level = Field(attribute='level', readonly=True)
+
     part = Field(attribute='part', widget=widgets.ForeignKeyWidget(Part))
 
-    part_name = Field(attribute='part__full_name', readonly=True)
+    parent_part_name = Field(attribute='part__full_name', readonly=True)
 
-    sub_part = Field(attribute='sub_part', widget=widgets.ForeignKeyWidget(Part))
+    id = Field(attribute='sub_part', widget=widgets.ForeignKeyWidget(Part))
 
     sub_part_name = Field(attribute='sub_part__full_name', readonly=True)
 
-    stock = Field(attribute='sub_part__total_stock', readonly=True)
+    sub_assembly = Field(attribute='sub_part__assembly', readonly=True)
 
     class Meta:
         model = BomItem
@@ -145,7 +147,7 @@ class BomItemResource(ModelResource):
         report_skipped = False
         clean_model_instances = True
 
-        exclude = ('checksum')
+        exclude = ['checksum', ]
 
 
 class BomItemAdmin(ImportExportModelAdmin):
diff --git a/InvenTree/part/bom.py b/InvenTree/part/bom.py
index 394314d461..a1f8b5ec6a 100644
--- a/InvenTree/part/bom.py
+++ b/InvenTree/part/bom.py
@@ -40,16 +40,43 @@ def MakeBomTemplate(fmt):
     return DownloadFile(data, filename)
 
 
-def ExportBom(part, fmt='csv'):
+def ExportBom(part, fmt='csv', cascade=False):
     """ Export a BOM (Bill of Materials) for a given part.
+
+    Args:
+        fmt: File format (default = 'csv')
+        cascade: If True, multi-level BOM output is supported. Otherwise, a flat top-level-only BOM is exported.
     """
 
     if not IsValidBOMFormat(fmt):
         fmt = 'csv'
 
-    bom_items = part.bom_items.all().order_by('id')
+    bom_items = []
 
-    dataset = BomItemResource().export(queryset=bom_items)
+    def add_items(items, level):
+        # Add items at a given layer
+        for item in items:
+
+            item.level = '-' * level
+
+            bom_items.append(item)
+
+            if item.sub_part.assembly:
+                add_items(item.sub_part.bom_items.all().order_by('id'), level + 1)
+        
+    if cascade:
+        # Cascading (multi-level) BOM
+
+        # Start with the top level
+        items_to_process = part.bom_items.all().order_by('id')
+
+        add_items(items_to_process, 1)
+
+    else:
+        # No cascading needed - just the top-level items
+        bom_items = [item for item in part.bom_items.all().order_by('id')]
+
+    dataset = BomItemResource().export(queryset=bom_items, cascade=cascade)
     data = dataset.export(fmt)
 
     filename = '{n}_BOM.{fmt}'.format(n=part.full_name, fmt=fmt)
diff --git a/InvenTree/part/views.py b/InvenTree/part/views.py
index c894c6ba99..584c8fe62f 100644
--- a/InvenTree/part/views.py
+++ b/InvenTree/part/views.py
@@ -1334,10 +1334,12 @@ class BomDownload(AjaxView):
 
         export_format = request.GET.get('file_format', 'csv')
 
+        cascade = str2bool(request.GET.get('cascade', False))
+
         if not IsValidBOMFormat(export_format):
             export_format = 'csv'
 
-        return ExportBom(part, fmt=export_format)
+        return ExportBom(part, fmt=export_format, cascade=cascade)
 
     def get_data(self):
         return {
@@ -1354,7 +1356,7 @@ class BomExport(AjaxView):
     ajax_form_title = _("Export Bill of Materials")
 
     def get(self, request, *args, **kwargs):
-        return self.renderJsonResponse(request, self.form_class())        
+        return self.renderJsonResponse(request, self.form_class())
 
     def post(self, request, *args, **kwargs):