[ENH] Implement delete item from db

learnware/market/database_ops.py

@@ -11,12 +11,13 @@ LOGGER = get_module_logger("market")
 
 def init_empty_db(func):
 
-    def wrapper():
-        if not os.path.exists(DB_PATH):
-            conn = sqlite3.connect(DB_PATH)
+    def wrapper(*args, **kwargs):
+        conn = sqlite3.connect(DB_PATH)
+        cur = conn.cursor()
+        listOfTables = cur.execute( """SELECT name FROM sqlite_master WHERE type='table' AND name='LEARNWARE'; """).fetchall()
+        if listOfTables == []:
             LOGGER.info("Initializing Database in %s..." % (DB_PATH))
-            c = conn.cursor()
-            c.execute(
+            cur.execute(
                 """CREATE TABLE LEARNWARE
             (ID CHAR(10) PRIMARY KEY     NOT NULL,
             NAME           TEXT    NOT NULL,
@@ -25,26 +26,30 @@ def init_empty_db(func):
             STAT_SPEC_PATH         TEXT NOT NULL);"""
             )
             LOGGER.info("Database Built!")
-            conn.commit()
-            conn.close()
-        func()
+        kwargs['cur'] = cur
+        kwargs['conn'] = conn
+        func(*args, **kwargs)
+        conn.commit()
+        conn.close()
 
     return wrapper
 
 @init_empty_db
-def add_learnware_to_db():
+def add_learnware_to_db(id:str, name:str, model_path:str, semantic_spec:dict):
     pass
 
 @init_empty_db
-def delete_learnware_from_db(id:str):
-    pass
+def delete_learnware_from_db(id:str, cur, conn):
+    cur.execute("DELETE from LEARNWARE where ID=%;")
+    conn.commit()
+    LOGGER.info("%d item has been deleted from table 'LEARNWARE'"%(conn.total_changes))
 
 @init_empty_db
-def load_market_from_db():
-    conn = sqlite3.connect(DB_PATH)
+def load_market_from_db(cur, conn):
+    # conn = sqlite3.connect(DB_PATH)
     LOGGER.info("Reload from Database")
-    c = conn.cursor()
-    cursor = c.execute("SELECT id, name, semantic_spec, model_path, stat_spec_path from LEARNWARE")
+    # c = conn.cursor()
+    cursor = cur.execute("SELECT id, name, semantic_spec, model_path, stat_spec_path from LEARNWARE")
 
     learnware_list = {}
     max_count = 0
@@ -62,7 +67,5 @@ def load_market_from_db():
         new_learnware = Learnware(id=id, name=name, model=model_dict, specification=specification)
         learnware_list[id] = new_learnware
         max_count = max(max_count, int(id))
-    conn.commit()
-    conn.close()
     LOGGER.info("Market Reloaded from DB.")
-    return learnware_list, max_count
+    return learnware_list, max_count+1