add link validation checker, which removes invalid entries

lib/db.py

@@ -1,6 +1,7 @@
 import sqlite3
 import mmh3
 import sys
+import requests
 DEBUG = False
 
 def log(*s):
@@ -91,3 +92,30 @@ def writedb(jobs):
                 else:
                     print("NEW_ENTRY")
                     cursor.execute("INSERT INTO jobs (star,tag,title,company,location,link,pubdate,hash) VALUES (?,?,?,?,?,?,?,?)",(job.starred,job.tag,job.title,job.company,job.location,job.link,job.date,hash1))
+
+def isStillValid(file):
+    rows = [0,0,0]
+    with sqlite3.connect(file) as connection:
+        cmd_read_chunk = f"""SELECT link from jobs;"""
+        cursor = connection.cursor()
+        cursor.execute(cmd_read_chunk)
+        
+        while(len(rows)!=0):
+            isLink = True
+            rows = []
+            rows = cursor.fetchmany(256)
+            for row in rows:
+                with requests.Session() as session:
+                    print("row: ",row[0])
+                    try:
+                        page = session.get(row[0])
+                    except:
+                        print("link is no valid URL so remove item")
+                        isLink = False
+
+                    finally:
+                        if page.ok == False or isLink == False:
+                            print("link is no more valid, remove item")
+                            rm_cursor = connection.cursor()
+                            rm_itm = rm_cursor.execute(f"""DELETE from jobs WHERE link = ?;""",(row[0],))
+                            print ("Deletion resultet in: ", rm_itm)