def find_by_retailer(self, retailer):
        """
        Pascal retailer:Retailer
        get a specific listentry by its retailer from the database
        :return: a single listentry bo
        """

        result = []
        cursor = self._cnx.cursor()
        cursor.execute(
            "SELECT ID, Article_ID, Retailer_ID, Shoppinglist_ID, User_ID, Group_ID, amount, bought,creationdate from `Listentry` WHERE Retailer_ID={}"
            .format(retailer))
        tuples = cursor.fetchall()

        try:
            for (id, article_id, retailer_id, shoppinglist_id, user_id,
                 group_id, amount, bought, cd) in tuples:
                le = ListEntry()
                le.set_id(id)
                le.set_article(article_id)
                le.set_retailer(retailer_id)
                le.set_shoppinglist(shoppinglist_id)
                le.set_user(user_id)
                le.set_group(group_id)
                le.set_amount(amount)
                le.set_buy_date(bought)
                le.set_creationdate(cd)
                result.append(le)
                print(result)
        except IndexError:
            result = None
        self._cnx.commit()
        cursor.close()
        return result
    def post(self):
        """
        Creates an specific ListEntry object.

        """
        adm = ShoppingAdministration()
        proposal = ListEntry.from_dict(api.payload)

        if proposal is not None:
            le = ListEntry()
            le.set_id(proposal.get_id())
            le.set_article(proposal.get_article())
            le.set_retailer(proposal.get_retailer())
            le.set_user(proposal.get_user())
            le.set_amount(proposal.get_amount())
            le.set_unit(proposal.get_unit())
            le.set_buy_date(proposal.get_buy_date())
            le.set_group(proposal.get_group())
            le.set_shoppinglist(proposal.get_shoppinglist())

            res = adm.insert_listentry(le)

            return res, 200
        else:
            return "", 500
    def find_by_key(self, key):
        """
        Niklas key:int
        gets the specific listentry with that specific from the database
        :return: a single listentry bo
        """
        result = None
        cursor = self._cnx.cursor()
        cursor.execute(
            "SELECT ID, Article_ID, Retailer_ID, Shoppinglist_ID, User_ID, Group_ID, amount, bought, creationdate from `Listentry` WHERE ID={}"
            .format(key))
        tuples = cursor.fetchall()
        print(tuples)
        try:
            for (id, article_id, retailer_id, shoppinglist_id, user_id,
                 group_id, amount, bought, cd) in tuples:
                le = ListEntry()
                le.set_id(id)
                le.set_article(article_id)
                le.set_retailer(retailer_id)
                le.set_shoppinglist(shoppinglist_id)
                le.set_user(user_id)
                le.set_group(group_id)
                le.set_amount(amount)
                le.set_buy_date(bought)
                le.set_creationdate(cd)
                result = le

        except IndexError:
            result = None

        self._cnx.commit()
        cursor.close()
        return result
    def get_personal_items_of_group(self, user_id, group_id):
        """
        Pascal
        gets all assigned listentries from the database for a specific user id, group id combination
        :return: a list of listentry bos
        """
        result = []
        cursor = self._cnx.cursor()
        statement = "SELECT Listentry.ID, Article.name as 'name', Category.name as 'category', Listentry.amount, Listentry.unit, Listentry.User_ID, Retailer.name as 'retailer', Article.ID FROM Listentry LEFT JOIN Retailer ON Listentry.Retailer_ID = Retailer.ID LEFT JOIN Article ON Listentry.Article_ID = Article.ID LEFT JOIN Category ON Article.CategoryID = Category.ID WHERE (Group_ID={0}) AND (User_ID={1} AND (bought is NULL))".format(
            group_id, user_id)

        cursor.execute(statement)
        tuples = cursor.fetchall()

        for (id, name, category, amount, unit, user_id, retailer,
             article_id) in tuples:
            listentry = ListEntry()
            listentry.set_id(id)
            listentry.set_name(name)
            listentry.set_category(category)
            listentry.set_amount(amount)
            listentry.set_unit(unit)
            listentry.set_user(user_id)
            listentry.set_retailer(retailer)
            listentry.set_article(article_id)
            listentry.set_shoppinglist(None)
            listentry.set_group(group_id)
            result.append(listentry)

        self._cnx.commit()
        cursor.close()

        return result
    def find_by_date_of_purchase(self, date):
        """
        Pascal date:Date
        """
        result = []
        cursor = self._cnx.cursor()
        cursor.execute(
            "SELECT ID, Article_ID, Retailer_ID, Shoppinglist_ID, User_ID, Group_ID, amount, bought,creationdate from `Listentry` WHERE bought={}"
            .format(date.get_bought))
        tuples = cursor.fetchall()
        print(tuples)

        try:
            for (id, article_id, retailer_id, shoppinglist_id, user_id,
                 group_id, amount, bought, cd) in tuples:
                le = ListEntry()
                le.set_id(id)
                le.set_article(article_id)
                le.set_retailer(retailer_id)
                le.set_shoppinglist(shoppinglist_id)
                le.set_user(user_id)
                le.set_group(group_id)
                le.set_amount(amount)
                le.set_buy_date(bought)
                le.set_creationdate(cd)
                result.append(le)
                print(result)
        except IndexError:
            result = None
        self._cnx.commit()
        cursor.close()
        return result
    def find_all(self):
        """
        Niklas
        get all listentries from the database
        :return: a list of listentry bos
        
        """
        result = []
        cursor = self._cnx.cursor()
        cursor.execute(
            "SELECT ID, Article_ID, Retailer_ID, Shoppinglist_ID, User_ID, Group_ID, amount, bought,creationdate from `Listentry`"
        )
        tuples = cursor.fetchall()

        try:
            for (id, article_id, retailer_id, shoppinglist_id, user_id,
                 group_id, amount, bought, cd) in tuples:
                le = ListEntry()
                le.set_id(id)
                le.set_article(article_id)
                le.set_retailer(retailer_id)
                le.set_shoppinglist(shoppinglist_id)
                le.set_user(user_id)
                le.set_group(group_id)
                le.set_amount(amount)
                le.set_buy_date(bought)
                le.set_creationdate(cd)
                result.append(le)

        except IndexError:
            result = None

        self._cnx.commit()
        cursor.close()
        return result
    def update(self, listentry):
        """
        Pascal le:ListEntry
        Niklas 
        updates an existing listentry in the database
        if it does not exist a new one is created
        :return: a single listentry bo
        """

        le = ListEntry()
        le = self.find_by_key(listentry.get_id())

        if listentry.get_article() != "" and listentry.get_article(
        ) is not None:
            le.set_article(listentry.get_article())
        if (listentry.get_retailer() != "" or listentry.get_retailer()
                is not None) and listentry.get_retailer() != "random-string":
            le.set_retailer(listentry.get_retailer())
        if listentry.get_shoppinglist() != "" and listentry.get_shoppinglist(
        ) is not None:
            le.set_shoppinglist(listentry.get_shoppinglist())
        if listentry.get_user() != "" or listentry.get_user() is not None:
            le.set_user(listentry.get_user())
        if listentry.get_group() != "" or listentry.get_group() is not None:
            le.set_group(listentry.get_group())
        if listentry.get_amount() != "" or listentry.get_amount() is not None:
            le.set_amount(listentry.get_amount())
        if listentry.get_unit() != "" or listentry.get_unit() is not None:
            le.set_unit(listentry.get_unit())
        if (listentry.get_buy_date() != "" and listentry.get_buy_date()
                is not None) and listentry.get_retailer() != "random-string":
            le.set_buy_date(listentry.get_buy_date())

        try:
            cursor = self._cnx.cursor()

            if le.get_unit() is None:
                unit = "NULL"
            else:
                unit = "'" + le.get_unit() + "'"

            if le.get_retailer() is None:
                retailer = 'NULL'
            else:
                retailer = le.get_retailer()

            if le.get_amount() is None:
                amount = 'NULL'
            else:
                amount = le.get_amount()

            if le.get_shoppinglist() is None:
                shoppinglist = "NULL"
            else:
                shoppinglist = le.get_shoppinglist()

            if le.get_user() is None:
                user = '******'
            else:
                user = le.get_user()

            if le.get_buy_date() is None and listentry.get_buy_date(
            ) != "random-string":
                buydate = 'NULL'
            else:
                date = datetime.date.today()
                buydate = "'" + date.strftime("%Y/%m/%d") + "'"

            command = """UPDATE Listentry SET Article_ID={0}, Retailer_ID={1}, Shoppinglist_ID={2}, User_ID={3}, Group_ID={4}, amount={5}, unit={6}, bought={7} WHERE ID={8}""".format(
                le.get_article(), retailer, shoppinglist, user, le.get_group(),
                amount, unit, buydate, le.get_id())
            print(command)

            cursor.execute(command)
            self._cnx.commit()
            cursor.close()
            return listentry

        except Exception as e:
            print(str(e))
            return "Error in update ListEntry ListEntryMapper: " + str(e)