serializes edge data as csv and json (#260)

network/templates/network/list_view.html

@@ -11,6 +11,13 @@
     <h1 class="display-1 text-center">
         <i class="bi bi-share"> Beziehungen</i>
     </h1>
+    <div class="text-center">
+        <h2>Download</h2>
+        <div class="btn-group" role="group" class="text-end">
+            <a type="button" class="btn btn-outline-primary" href="{% url 'network:data' %}{% querystring %}&format=csv">CSV</a>
+            <a type="button" class="btn btn-outline-primary" href="{% url 'network:data' %}{% querystring %}&format=json">JSON</a>
+        </div>
+    </div>
 
     <div class="row pt-4">
         <div class="col-md-4" id="searchpane">

network/urls.py

@@ -1,8 +1,9 @@
 from django.urls import path
-from network.views import EdgeListViews
+from network.views import EdgeListViews, network_data
 
 
 app_name = "network"
 urlpatterns = [
     path("edges/", EdgeListViews.as_view(), name="edges_browse"),
+    path("csv/", network_data, name="data"),
 ]

network/views.py

@@ -1,3 +1,8 @@
+import pandas as pd
+import json
+from django.http import HttpResponse, JsonResponse
+
+
 from browsing.browsing_utils import (
     GenericListView,
 )
@@ -21,3 +26,31 @@ class EdgeListViews(GenericListView):
     ]
     enable_merge = False
     template_name = "network/list_view.html"
+
+
+def network_data(request):
+    values_list = [x.name for x in Edge._meta.get_fields()]
+    qs = EdgeListFilter(request.GET, queryset=Edge.objects.all()).qs
+    items = list(qs.values_list(*values_list))
+    df = pd.DataFrame(items, columns=values_list)
+    response = HttpResponse(
+        content_type="text/csv",
+    )
+    format = request.GET.get("format", "csv")
+    if format not in ["csv", "json"]:
+        format = "csv"
+    if format == "csv":
+        response = HttpResponse(
+            content_type="text/csv",
+            headers={"Content-Disposition": 'attachment; filename="relations.csv"'},
+        )
+        df.to_csv(response, index=False)
+    else:
+        df = df.set_index("edge_id")
+        df["start_date"] = pd.to_datetime(df["start_date"], errors="coerce")
+        df["end_date"] = pd.to_datetime(df["end_date"], errors="coerce")
+        df["start_date"] = df["start_date"].dt.strftime("%Y-%m-%d").fillna("")
+        df["end_date"] = df["end_date"].dt.strftime("%Y-%m-%d").fillna("")
+        out = df.to_json(orient="index", force_ascii=False)
+        response = JsonResponse(json.loads(out))
+    return response