Add snapshot plot

nummi/main/templates/main/snapshot.html

@@ -31,6 +31,9 @@
 	</div>
 </form>
 
+<h2>Plot</h2>
+<img src="{% url 'snapshot_graph' snapshot.id %}" />
+
 {% if snapshot.transactions %}
 <h2>Transactions ({% pmvalue sum %} / {% pmvalue snapshot.diff %})</h2>
 

nummi/main/urls.py

@@ -17,5 +17,6 @@ urlpatterns = [
     path("category/<uuid>/del", views.del_category, name="del_category"),
     path("snapshot", views.snapshot, name="snapshot"),
     path("snapshot/<uuid>", views.snapshot, name="snapshot"),
+    path("snapshot/<uuid>/graph.svg", views.snapshot_graph, name="snapshot_graph"),
     path("snapshot/<uuid>/del", views.del_snapshot, name="del_snapshot"),
 ]

nummi/main/views.py

@@ -5,6 +5,9 @@ from django.contrib.auth import views as auth_views
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.views.generic import ListView
 from django.core.paginator import Paginator
+from django.db import models
+import matplotlib.pyplot as plt
+import tempfile
 
 from .models import (
     Transaction,
@@ -169,6 +172,47 @@ def snapshot(request, uuid=None):
     )
 
 
+@login_required
+def snapshot_graph(request, uuid):
+    _snapshot = get_object_or_404(Snapshot, id=uuid)
+    _categories_p = (
+        _snapshot.transactions.filter(value__gt=0)
+        .values("category")
+        .annotate(sum=models.Sum("value"))
+    )
+    _categories_m = (
+        _snapshot.transactions.filter(value__lt=0)
+        .values("category")
+        .annotate(sum=models.Sum("value"))
+    )
+
+    print(_categories_p)
+    print(_categories_m)
+    fig, ax = plt.subplots()
+    ax.bar(
+        [
+            "*" if (c := _cat["category"]) is None else Category.objects.get(id=c).name
+            for _cat in _categories_p
+        ],
+        [_cat["sum"] for _cat in _categories_p],
+        color="#007339",
+    )
+    ax.bar(
+        [
+            "*" if (c := _cat["category"]) is None else Category.objects.get(id=c).name
+            for _cat in _categories_m
+        ],
+        [_cat["sum"] for _cat in _categories_m],
+        color="#bf1500",
+    )
+    ax.grid(color="k", alpha=0.2)
+    ax.set(ylabel="Value (€)")
+    with tempfile.NamedTemporaryFile(suffix=".svg") as f:
+        fig.savefig(f.name)
+        f.seek(0)
+        return HttpResponse(f.read(), content_type="image/svg+xml")
+
+
 @login_required
 def del_snapshot(request, uuid):
     _snapshot = get_object_or_404(Snapshot, id=uuid)