Export user book data as csv (#1556)

Simple book data export

bookwyrm/views/preferences/export.py

@@ -0,0 +1,97 @@
+""" Let users export their book data """
+import csv
+
+from django.contrib.auth.decorators import login_required
+from django.db.models import Q
+from django.http import StreamingHttpResponse
+from django.template.response import TemplateResponse
+from django.views import View
+from django.utils.decorators import method_decorator
+from django.views.decorators.http import require_GET
+
+from bookwyrm import models
+
+# pylint: disable=no-self-use
+@method_decorator(login_required, name="dispatch")
+class Export(View):
+    """Let users export data"""
+
+    def get(self, request):
+        """Request csv file"""
+        return TemplateResponse(request, "preferences/export.html")
+
+
+@login_required
+@require_GET
+def export_user_book_data(request):
+    """Streaming the csv file of a user's book data"""
+    data = (
+        models.Edition.viewer_aware_objects(request.user)
+        .filter(
+            Q(shelves__user=request.user)
+            | Q(readthrough__user=request.user)
+            | Q(review__user=request.user)
+            | Q(comment__user=request.user)
+            | Q(quotation__user=request.user)
+        )
+        .distinct()
+    )
+
+    generator = csv_row_generator(data, request.user)
+
+    pseudo_buffer = Echo()
+    writer = csv.writer(pseudo_buffer)
+    # for testing, if you want to see the results in the browser:
+    # from django.http import JsonResponse
+    # return JsonResponse(list(generator), safe=False)
+    return StreamingHttpResponse(
+        (writer.writerow(row) for row in generator),
+        content_type="text/csv",
+        headers={"Content-Disposition": 'attachment; filename="bookwyrm-export.csv"'},
+    )
+
+
+def csv_row_generator(books, user):
+    """generate a csv entry for the user's book"""
+    deduplication_fields = [
+        f.name
+        for f in models.Edition._meta.get_fields()  # pylint: disable=protected-access
+        if getattr(f, "deduplication_field", False)
+    ]
+    fields = (
+        ["title", "author_text"]
+        + deduplication_fields
+        + ["rating", "review_name", "review_cw", "review_content"]
+    )
+    yield fields
+    for book in books:
+        # I think this is more efficient than doing a subquery in the view? but idk
+        review_rating = (
+            models.Review.objects.filter(user=user, book=book, rating__isnull=False)
+            .order_by("-published_date")
+            .first()
+        )
+
+        book.rating = review_rating.rating if review_rating else None
+
+        review = (
+            models.Review.objects.filter(user=user, book=book, content__isnull=False)
+            .order_by("-published_date")
+            .first()
+        )
+        if review:
+            book.review_name = review.name
+            book.review_cw = review.content_warning
+            book.review_content = review.raw_content
+        yield [getattr(book, field, "") or "" for field in fields]
+
+
+class Echo:
+    """An object that implements just the write method of the file-like
+    interface. (https://docs.djangoproject.com/en/3.2/howto/outputting-csv/)
+    """
+
+    # pylint: disable=no-self-use
+    def write(self, value):
+        """Write the value by returning it, instead of storing in a buffer."""
+        return value