From 7215a563b19cf470d77adc299109861e0166a098 Mon Sep 17 00:00:00 2001
From: Oliver Walters <oliver.henry.walters@gmail.com>
Date: Fri, 22 May 2020 21:22:43 +1000
Subject: [PATCH] Add PartFilterMixin

---
 InvenTree/report/models.py | 100 ++++++++++++++++++++++++++++++++++---
 1 file changed, 92 insertions(+), 8 deletions(-)

diff --git a/InvenTree/report/models.py b/InvenTree/report/models.py
index 46fdd965e7..ffd77a09b1 100644
--- a/InvenTree/report/models.py
+++ b/InvenTree/report/models.py
@@ -9,9 +9,12 @@ import os
 
 from django.db import models
 from django.core.validators import FileExtensionValidator
+from django.core.exceptions import ValidationError
 
 from django.utils.translation import gettext_lazy as _
 
+from part.models import Part
+
 from django_tex.shortcuts import render_to_pdf
 from django_weasyprint import WeasyTemplateResponseMixin
 
@@ -23,6 +26,59 @@ def rename_template(instance, filename):
     return os.path.join('report', 'report_template', instance.getSubdir(), filename)
 
 
+def validateFilterString(value):
+    """
+    Validate that a provided filter string looks like a list of comma-separated key=value pairs
+
+    These should nominally match to a valid database filter based on the model being filtered.
+
+    e.g. "category=6, IPN=12"
+    e.g. "part__name=widget"
+
+    The ReportTemplate class uses the filter string to work out which items a given report applies to.
+    For example, an acceptance test report template might only apply to stock items with a given IPN,
+    so the string could be set to:
+
+    filters = "IPN = ACME0001"
+
+    Returns a map of key:value pairs
+    """
+
+    # Empty results map
+    results = {}
+
+    value = str(value).strip()
+
+    if not value or len(value) == 0:
+        return results
+
+    groups = value.split(',')
+
+    for group in groups:
+        group = group.strip()
+
+        pair = group.split('=')
+
+        if not len(pair) == 2:
+            raise ValidationError(
+                "Invalid group: {g}".format(g=group)
+            )
+
+        k, v = pair
+
+        k = k.strip()
+        v = v.strip()
+
+        if not k or not v:
+            raise ValidationError(
+                "Invalid group: {g}".format(g=group)
+            )
+
+        results[k] = v
+
+    return results
+
+
 class WeasyprintReportMixin(WeasyTemplateResponseMixin):
     """
     Class for rendering a HTML template to a PDF.
@@ -101,13 +157,6 @@ class ReportTemplateBase(models.Model):
 
     description = models.CharField(max_length=250, help_text=_("Report template description"))
 
-    filters = models.CharField(
-        blank=True,
-        max_length=250,
-        help_text=_("Query filters (comma-separated list of key=value pairs)"),
-        validators=[validate_filter_string]
-    )
-
     class Meta:
         abstract = True
 
@@ -121,7 +170,42 @@ class ReportTemplate(ReportTemplateBase):
     pass
 
 
-class TestReport(ReportTemplateBase):
+class PartFilterMixin(models.Model):
+    """
+    A model mixin used for matching a report type against a Part object.
+    Used to assign a report to a given part using custom filters.
+    """
+
+    class Meta:
+        abstract = True
+
+    def matches_part(self, part):
+        """
+        Test if this report matches a given part.
+        """
+
+        filters = self.get_part_filters()
+
+        parts = Part.objects.filter(**filters)
+
+        parts = parts.filter(pk=part.pk)
+
+        return parts.exists()
+
+
+    def get_part_filters(self):
+        """ Return a map of filters to be used for Part filtering """
+        return validateFilterString(self.part_filters)
+
+    part_filters = models.CharField(
+        blank=True,
+        max_length=250,
+        help_text=_("Part query filters (comma-separated list of key=value pairs)"),
+        validators=[validateFilterString]
+    )
+
+
+class TestReport(ReportTemplateBase, PartFilterMixin):
     """
     Render a TestReport against a StockItem object.
     """