Handle dropdown menu value

Question

Good time I have two dropdowns on one page The first is a list of cars and the second is the model of the cars. Now, when I select Mercedes in the first drop-down menu, for example, I want the exact model name of the car brand to appear in the second drop-down menu. For example, I choose Mercedes and in the next drop down, the list of Mercedes cars will be shown to me. How can I handle it?

I am a newbie. And maybe it is better to give a more comprehensive explanation

can you include your current snippet, [This](https://stackoverflow.com/a/73446365/10157127) may answer your question. — Md. Yeasin Sheikh, Aug 04 '23 at 15:46

Canilho · Answer 1 · 2023-08-04T15:59:03.087

There are several ways to handle this. You can track the selected field, by adding it as a variable on your application, and everytime you select a new value, that variable is changed ex:

manufacturer = "Mercedes"

You can either have a variable (flag) in the builder that changes what is presented depending on its value, Ex: when a new value is selected on the first dropdown, you change the value of a variable, and the second dropdown loads a list based on that value. Ex:

if (manufacturer == "Mercedes") { // load mercedes list on 2nd dropdown }

or

Create a state change where you load different values to the list depending on the selected value, with a stateChange of a StatefulWidget.

I don't think first approach is good – user1209216 Aug 04 '23 at 19:25 — user1209216, Aug 04 '23 at 19:25

score 0 · Answer 2 · answered Aug 05 '23 at 03:17

Use Map to store the Manufacturer. For e.g. :

Map<String,String> manufacturer = {'1':'BMW','2':'Toyota'};

And also store list of cars using a map like this:

Map<String,List<String>> cars = {
    '1':{'BMW car1','BMW car2'},
    '2':{'Toyota car1','Toyota car2'},
};

Then create a key variable which will stored key of selected brand.

String key ='1';

Then U can now choose the cars u desire using the key u chose for brand in dropdown.

Handle dropdown menu value

2 Answers2