[fix] check against all linked documents while canceling or deleting (#2360)

frappe/model/delete_doc.py

@@ -168,16 +168,16 @@ def check_if_doc_is_linked(doc, method="Delete"):
 
 	for link_dt, link_field, issingle in link_fields:
 		if not issingle:
-			item = frappe.db.get_value(link_dt, {link_field:doc.name},
-				["name", "parent", "parenttype", "docstatus"], as_dict=True)
-			if item and ((item.parent or item.name) != doc.name) \
-					and ((method=="Delete" and item.docstatus<2) or (method=="Cancel" and item.docstatus==1)):
-				# raise exception only if
-				# linked to an non-cancelled doc when deleting
-				# or linked to a submitted doc when cancelling
-				frappe.throw(_("Cannot delete or cancel because {0} {1} is linked with {2} {3}")
-					.format(doc.doctype, doc.name, item.parenttype if item.parent else link_dt,
-					item.parent or item.name), frappe.LinkExistsError)
+			for item in frappe.db.get_values(link_dt, {link_field:doc.name},
+				["name", "parent", "parenttype", "docstatus"], as_dict=True):
+				if item and ((item.parent or item.name) != doc.name) \
+						and ((method=="Delete" and item.docstatus<2) or (method=="Cancel" and item.docstatus==1)):
+					# raise exception only if
+					# linked to an non-cancelled doc when deleting
+					# or linked to a submitted doc when cancelling
+					frappe.throw(_("Cannot delete or cancel because {0} {1} is linked with {2} {3}")
+						.format(doc.doctype, doc.name, item.parenttype if item.parent else link_dt,
+						item.parent or item.name), frappe.LinkExistsError)
 
 def check_if_doc_is_dynamically_linked(doc, method="Delete"):
 	'''Raise `frappe.LinkExistsError` if the document is dynamically linked'''