Allow Table.get by doc_id to have O(1) behavior

tinydb/table.py

@@ -289,7 +289,7 @@ def get(
         if doc_id is not None:
             # Retrieve a document specified by its ID
             table = self._read_table()
-            raw_doc = table.get(doc_id, None)
+            raw_doc = table.get(str(doc_id), None)
 
             if raw_doc is None:
                 return None
@@ -610,20 +610,7 @@ def __len__(self):
         Count the total number of documents in this table.
         """
 
-        # Using self._read_table() will convert all documents into
-        # the document class. But for counting the number of documents
-        # this conversion is not necessary, thus we read the storage
-        # directly here
-
-        tables = self._storage.read()
-
-        if tables is None:
-            return 0
-
-        try:
-            return len(tables[self.name])
-        except KeyError:
-            return 0
+        return len(self._read_table())
 
     def __iter__(self) -> Iterator[Document]:
         """
@@ -635,7 +622,7 @@ def __iter__(self) -> Iterator[Document]:
         # Iterate all documents and their IDs
         for doc_id, doc in self._read_table().items():
             # Convert documents to the document class
-            yield self.document_class(doc, doc_id)
+            yield self.document_class(doc, self.document_id_class(doc_id))
 
     def _get_next_id(self):
         """
@@ -672,14 +659,13 @@ def _get_next_id(self):
 
         return next_id
 
-    def _read_table(self) -> Dict[int, Mapping]:
+    def _read_table(self) -> Dict[str, Mapping]:
         """
         Read the table data from the underlying storage.
 
-        Here we read the data from the underlying storage and convert all
-        IDs to the document ID class. Documents themselves are NOT yet
-        transformed into the document class, we may not want to convert
-        *all* documents when returning only one document for example.
+        Documents and doc_ids are NOT yet transformed, as 
+        we may not want to convert *all* documents when returning
+        only one document for example.
         """
 
         # Retrieve the tables from the storage
@@ -696,12 +682,7 @@ def _read_table(self) -> Dict[int, Mapping]:
             # The table does not exist yet, so it is empty
             return {}
 
-        # Convert all document IDs to the correct document ID class and return
-        # the table data dict
-        return {
-            self.document_id_class(doc_id): doc
-            for doc_id, doc in table.items()
-        }
+        return table
 
     def _update_table(self, updater: Callable[[Dict[int, Mapping]], None]):
         """