basic feed rebuilding

repub/exporters.py

@@ -0,0 +1,49 @@
+from scrapy.exporters import BaseItemExporter
+
+from .items import ChannelElementItem
+from .exceptions import *
+
+from typing import Any
+from io import BytesIO
+
+
+from repub import rss
+
+
+class RssExporter(BaseItemExporter):
+    def __init__(self, file: BytesIO, **kwargs: Any):
+        super().__init__(**kwargs)
+        if not self.encoding:
+            self.encoding = "utf-8"
+        self.file: BytesIO = file
+        self.rss = rss.rss()
+        self.channel = None
+        self.item_buffer = []
+
+    def start_exporting(self) -> None:
+        pass
+
+    def export_item(self, item: Any):
+        if isinstance(item, ChannelElementItem):
+            self.channel = item.el
+            self.rss.append(item.el)
+            self.flush_buffer()
+            return
+
+        if not self.channel:
+            self.item_buffer.append(item)
+        else:
+            self.export_rss_item(item)
+
+    def flush_buffer(self):
+        for item in self.item_buffer:
+            self.export_rss_item(item)
+        self.item_buffer = []
+
+    def export_rss_item(self, item: Any):
+        assert self.channel is not None
+        self.channel.append(item.el)
+
+    def finish_exporting(self) -> None:
+        xml_bytes = rss.serialize(self.rss)
+        self.file.write(xml_bytes)