refactor kw database as a member variable

db.py

@@ -16,6 +16,7 @@ class db():
         self.client = MongoClient('localhost', 27017)
         self.c_sources = self.client[self.DB]["sources"]
         self.c_articles = self.client[self.DB]["articles"]
+        self.c_kw = self.client[self.DB]["keywords"]
 
     def change_timezone(self, el):
         #gmt = pytz.timezone("America/Buenos_Aires")  # FIXME
@@ -159,11 +160,11 @@ class db():
         return [re.compile('\\b' + w.lower() + '\\b') for w in arr]
 
     def get_keywords_list(self):
-        kw = self.client[self.DB]["keywords"]
+        kw = self.c_kw
         return [k["keyword"] for k in kw.find({})]
 
     def get_keywords(self, category):
-        kw = self.client[self.DB]["keywords"]
+        kw = self.c_kw
         ret = [{"weight": k["weight"],
                 "kw": k["keyword"],
                 "pattern": self.to_regex(k["keyword"].split("|"))} for k in kw.find({})]
@@ -171,7 +172,7 @@ class db():
         return ret
 
     def add_keyword(self, kw, weight):
-        kwdb = self.client[self.DB]["keywords"]
+        kwdb = self.c_kw
         try:
             data = {'keyword': kw, 'weight': weight}
             kwdb.insert_one(data)
@@ -185,7 +186,7 @@ class db():
             return False
 
         kw["pattern"] = self.to_regex(kw["keyword"].split("|"))
-        kwdb = self.client[self.DB]["keywords"]
+        kwdb = self.c_kw
         try:
             kwdb.update({'keyword': kw['keyword']}, {'$set': kw})
             return True
@@ -194,7 +195,7 @@ class db():
             return False
 
     def delete_keyword(self, kw):
-        kwdb = self.client[self.DB]["keywords"]
+        kwdb = self.c_kw
         try:
             kwdb.remove({'keyword': kw})
             return True