feat: add compression for file storage and retrieval in knowledge.py

Author: liuruibin

apps/knowledge/models/knowledge.py

@@ -1,3 +1,5 @@
+import io
+import zipfile
 from enum import Enum
 
 import uuid_utils.compat as uuid
@@ -276,19 +278,38 @@ class Meta:
 
     def save(self, bytea=None, force_insert=False, force_update=False, using=None, update_fields=None):
         sha256_hash = get_sha256_hash(bytea)
+        # 创建压缩文件
+        zip_buffer = io.BytesIO()
+        with zipfile.ZipFile(zip_buffer, 'w', zipfile.ZIP_DEFLATED) as zip_file:
+            # 设置压缩级别为最高(9)
+            zipinfo = zipfile.ZipInfo(self.file_name)
+            zipinfo.compress_type = zipfile.ZIP_DEFLATED
+            zip_file.writestr(zipinfo, bytea, compresslevel=9)
+        # 获取压缩后的数据
+        compressed_data = zip_buffer.getvalue()
         f = QuerySet(File).filter(sha256_hash=sha256_hash).first()
         if f is not None:
             self.loid = f.loid
         else:
             result = select_one("SELECT lo_from_bytea(%s, %s::bytea) as loid", [0, bytea])
             self.loid = result['loid']
-        self.file_size = len(bytea)
+        self.file_size = len(compressed_data)
         self.sha256_hash = sha256_hash
+        # 可以在元数据中记录原始大小
+        if 'original_size' not in self.meta:
+            self.meta['original_size'] = len(bytea)
         super().save()
 
     def get_bytes(self):
         result = select_one(f'SELECT lo_get({self.loid}) as "data"', [])
-        return result['data']
+        compressed_data = result['data']
+        try:
+            # 解压数据
+            with zipfile.ZipFile(io.BytesIO(compressed_data)) as zip_file:
+                return zip_file.read(self.file_name)
+        except Exception as e:
+            # 如果数据不是zip格式，直接返回原始数据
+            return compressed_data
 
 
 @receiver(pre_delete, sender=File)