Refactor API for document and session (#2819)

### What problem does this PR solve?

Refactor API for document and session.

### Type of change


- [x] Refactoring

---------

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>

api/db/services/document_service.py

@@ -49,6 +49,29 @@ from rag.utils.redis_conn import REDIS_CONN
 class DocumentService(CommonService):
     model = Document
 
+    @classmethod
+    @DB.connection_context()
+    def get_list(cls, kb_id, page_number, items_per_page,
+                     orderby, desc, keywords, id):
+        docs =cls.model.select().where(cls.model.kb_id==kb_id)
+        if id:
+            docs = docs.where(
+                cls.model.id== id )
+        if keywords:
+            docs = docs.where(
+                fn.LOWER(cls.model.name).contains(keywords.lower())
+            )
+        count = docs.count()
+        if desc:
+            docs = docs.order_by(cls.model.getter_by(orderby).desc())
+        else:
+            docs = docs.order_by(cls.model.getter_by(orderby).asc())
+
+        docs = docs.paginate(page_number, items_per_page)
+
+        return list(docs.dicts()), count
+
+
     @classmethod
     @DB.connection_context()
     def get_by_kb_id(cls, kb_id, page_number, items_per_page,
@@ -268,7 +291,7 @@ class DocumentService(CommonService):
     @classmethod
     @DB.connection_context()
     def get_thumbnails(cls, docids):
-        fields = [cls.model.id, cls.model.kb_id, cls.model.thumbnail]
+        fields = [cls.model.id, cls.model.thumbnail]
         return list(cls.model.select(
             *fields).where(cls.model.id.in_(docids)).dicts())