write to csv file problem

[jacksfrustration]

i have the following function:

my_list=save_ent()
    new_list=[]

    for ent in my_list:
        new_list.append(output_found_flights(ent))
    try:
        data_file=pd.read_csv("flight_data.csv")
        data_dict=data_file.to_dict(orient="records")
    except pandas.errors.EmptyDataError:
        messagebox.showerror(title="Oooops",message="There are no saved information")
        data_dict=[]
    finally:
        for ent in new_list:
            data_dict.append(ent)
        try:
            for i,ent in enumerate(data_dict):
                res= not all (ent.values())
                if str(res):
                    data_dict.pop(i)
        except AttributeError:
            data_dict.pop(i)

        finally:

            new_data_file=pd.DataFrame(data_dict)
            new_data_file.to_csv("flight_data.csv",index=False)

the problem is the first time i run the code it executes correctly. When i try to add more search results it overwrites the csv file as expected but it gets rid of the previous search result and replaces it with the following

Output:
0
""

ok i tried changing the mode as you suggested. i have the following code now

    my_list=save_ent()
    new_list=[]

    for ent in my_list:
        
        new_list.append(output_found_flights(ent))
    new_data_file=pd.DataFrame(new_list)
    new_data_file.to_csv("flight_data.csv",index=False,mode="a")

but i still get the following addition on my csv file

Output:
0
""

in my code i have the output_found_flights function being called. the code for that follows

def output_found_flights(ent):
    '''connects to the api in order to find flights. information from entries are received
    generates values in the current entry that is supplied when the function is called
    and returns the updated dictionary file'''
    query = {
        "fly_from": ent['from_iata_code'],
        "fly_to": ent['to_iata_code'],
        "date_from": ent['from_time'],
        "date_to": ent["to_time"],
        "nights_in_dst_from": 7,
        "nights_in_dst_to": 28,
        "flight_type": "round",
        "one_for_city": 1,
        "max_stopovers": 0,
        "curr": "GBP"
    }
    headers = {
        "apikey": API_KEY
    }
    endpoint = "https://api.tequila.kiwi.com/v2/search"
    response = requests.get(url=endpoint, headers=headers, params=query)
    flights = response.json()
    try:
        lowest_price = round(float(ent["lowest_price"]), 2)
    except ValueError:
        messagebox.showerror(title="Ooops",
                             message="You have not entered appropriate input for the lowest price variable")

    for i in range(0, len(flights['data'])):
        flight_price = round(float(flights['data'][0]['price']), 2)
        if flight_price <= lowest_price:
            adult_price=flights['data'][i]['fare']['adults']
            children_price=flights['data'][i]['fare']['children']
            infants_price=flights['data'][i]['fare']['infants']
            total_price=float((adult_price * ent['adults'] ) + (children_price * ent['children']) + (infants_price * ent['infants']))
            url = flights['data'][i]['deep_link']
            date = flights['data'][i]['local_departure']
            date_separator = date.find("T")
            departure_date = date[:date_separator]
            date_list = departure_date.split("-")
            date_formatted = f"{date_list[2]}/{date_list[1]}/{date_list[0]}"
            ent['trip_date'] = date_formatted
            ent["ticket_price"] = flight_price
            ent['total_price']=total_price
            ent['url'] = url
            try:
                if messagebox.askokcancel(title=f"{ent['trip_date']} from {ent['from_city_name']} to {ent['to_city_name']}",message=f"Ticket price is £{ent['total_price']}0\n"
                                                                                                                                       f"{int(ent['adults'])} adults are travelling with {int(ent['children'])} children and {int(ent['infants'])} infants.\nPress ok to open the URL in order to buy the tickets"):
                    webbrowser.open(ent['url'])
            except ValueError:
                messagebox.showerror(title="Ooops",message="No flights were found")


            return ent

ent from the output_found_flights gets returned as empty the way i understand it. that is why i included the function code so you can help me figure out how to beat this