Update sqlite3/Files/README.md

sqlite3/Files/README.md

@@ -1,4 +1,5 @@
 ```python
+# files.py
 import pandas as pd
 
 class Files:
@@ -6,7 +7,7 @@ class Files:
     def __init__(self, db='files.sqlite'):
         import sqlite3
         if not db.endswith('.sqlite'): db += '.sqlite'
-        self.conn = sqlite3.connect(db, isolation_level=None)
+        self.conn = sqlite3.connect(db, isolation_level=None, timeout=60)
         self.conn.row_factory = sqlite3.Row
         self("PRAGMA journal_mode=WAL")
         self("CREATE TABLE IF NOT EXISTS files (filename TEXT PRIMARY KEY, content BLOB)")
@@ -16,13 +17,14 @@ class Files:
 
     def __setitem__(self, filename, content) -> None:
         assert isinstance(filename, str)
-        if isinstance(content, str):
-            content = content.encode()
+        if isinstance(content, str): content = content.encode()
         assert isinstance(content, bytes)
         self("INSERT OR REPLACE INTO files VALUES (?,?)", (filename, content))
 
     def __getitem__(self, filename) -> bytes:
-        return self("SELECT content FROM files WHERE filename=?", (filename,)).content[0]
+        result = self("SELECT content FROM files WHERE filename=?", (filename,))
+        if result.empty: raise KeyError(filename)
+        return result.content[0]
 
     def __delitem__(self, filename) -> None:
         self("DELETE FROM files WHERE filename=?", (filename,))
@@ -34,23 +36,36 @@ class Files:
     def __contains__(self, filename: str) -> bool:
         return not self("SELECT 1 FROM files WHERE filename=?", (filename,)).empty
 
-    def __len__(self) -> int:
-        return self("SELECT COUNT(*) FROM files").iloc[0, 0]
-
+    def __len__(self): return self("SELECT COUNT(*) FROM files").iloc[0, 0]
+    def __enter__(self): return self
+    def __exit__(self, exc_type, exc_val, exc_tb): self.close()
+    def __del__(self): self.close()
+    
+    def close(self):
+        if self.conn:
+            self('PRAGMA wal_checkpoint(FULL)')
+            self.conn.close()
+            self.conn = None
 
 if __name__ == "__main__":
-    files = Files()
-    for filename in files:
-        print(files[filename])
-    files['hello'] = 'world'
-    print(files['hello'])
-    print(len(files))
-    print('hello' in files)
-    for filename in files:
+    fs = Files()
+    for filename in fs:
+        print(filename, fs[filename])
+    fs['hello'] = 'world'
+    print(fs['hello'])
+    print(len(fs))
+
+    print('hello' in fs)
+    for filename in fs:
         print(filename)
 
-    del files['hello']
-    for filename in files:
+    del fs['hello']
+    for filename in fs:
         print(filename)
 
+    with Files() as fs:
+        fs['world'] = '1234'
+        print(fs['world'])
+        print(len(fs))
+
 ```