Flutter DropdownSearch

February 13, 2023 Dropdown

Flutter simple and robust DropdownSearch with the item search feature, making it possible to use an offline item list or filtering URL for easy customization.

Key Features

Sync and/or Async items (online, offline, DB, …)
Searchable dropdown
Three dropdown mode: Menu/ BottomSheet/ ModalBottomSheet / Dialog
Single & multi selection
Material dropdown
Easy customizable UI
Handle Light and Dark theme
Easy implementation into statelessWidget
Support multi level items

packages.yaml

dropdown_search: <lastest version>

Import

import 'package:dropdown_search/dropdown_search.dart';

Simple implementation

DropdownSearch<String>(
    popupProps: PopupProps.menu(
        showSelectedItems: true,
        disabledItemFn: (String s) => s.startsWith('I'),
    ),
    items: ["Brazil", "Italia (Disabled)", "Tunisia", 'Canada'],
    dropdownDecoratorProps: DropDownDecoratorProps(
        dropdownSearchDecoration: InputDecoration(
            labelText: "Menu mode",
            hintText: "country in menu mode",
        ),
    ),
    onChanged: print,
    selectedItem: "Brazil",
)

DropdownSearch<String>.multiSelection(
    items: ["Brazil", "Italia (Disabled)", "Tunisia", 'Canada'],
    popupProps: PopupPropsMultiSelection.menu(
        showSelectedItems: true,
        disabledItemFn: (String s) => s.startsWith('I'),
    ),
    onChanged: print,
    selectedItems: ["Brazil"],
)

customize showed field (itemAsString)

DropdownSearch<UserModel>(
    asyncItems: (String filter) => getData(filter),
    itemAsString: (UserModel u) => u.userAsStringByName(),
    onChanged: (UserModel? data) => print(data),
    dropdownDecoratorProps: DropDownDecoratorProps(
        dropdownSearchDecoration: InputDecoration(labelText: "User by name"),
    ),
)

DropdownSearch<UserModel>(
    asyncItems: (String filter) => getData(filter),
    itemAsString: (UserModel u) => u.userAsStringById(),
    onChanged: (UserModel? data) => print(data),
    dropdownDecoratorProps: DropDownDecoratorProps(
        dropdownSearchDecoration: InputDecoration(labelText: "User by id"),
    ),
)

customize Filter Function

DropdownSearch<UserModel>(
    filterFn: (user, filter) =>
    user.userFilterByCreationDate(filter),
    asyncItems: (String filter) => getData(filter),
    itemAsString: (UserModel u) => u.userAsStringByName(),
    onChanged: (UserModel? data) => print(data),
    dropdownDecoratorProps: DropDownDecoratorProps(
        dropdownSearchDecoration: InputDecoration(labelText: "Name"),
    ),
)

customize Search Mode

DropdownSearch<UserModel>(
    popupProps: PopupProps.bottomSheet(),
    dropdownSearchDecoration: InputDecoration(labelText: "Name"),
    asyncItems: (String filter) => getData(filter),
    itemAsString: (UserModel u) => u.userAsString(),
    onChanged: (UserModel? data) => print(data),
)

Validation

DropdownSearch(
    items: ["Brazil", "France", "Tunisia", "Canada"],
    dropdownSearchDecoration: InputDecoration(labelText: "Name"),
    onChanged: print,
    selectedItem: "Tunisia",
    validator: (String? item) {
    if (item == null)
      return "Required field";
    else if (item == "Brazil")
      return "Invalid item";
    else
      return null;
    },
)

Endpoint implementation (using Dio package)

DropdownSearch<UserModel>(
    dropdownSearchDecoration: InputDecoration(labelText: "Name"),
    asyncItems: (String filter) async {
        var response = await Dio().get(
            "http://5d85ccfb1e61af001471bf60.mockapi.io/user",
            queryParameters: {"filter": filter},
        );
        var models = UserModel.fromJsonList(response.data);
        return models;
    },
    onChanged: (UserModel? data) {
      print(data);
    },
)

Layout customization

You can customize the layout of the DropdownSearch and its items. EXAMPLE

Full documentation here

Attention

To use a template as an item type, and you don’t want to use a custom function itemAsString and compareFn you need to implement toString, equals and hashcode, as shown below:

class UserModel {
  final String id;
  final DateTime createdAt;
  final String name;
  final String avatar;

  UserModel({this.id, this.createdAt, this.name, this.avatar});

  factory UserModel.fromJson(Map<String, dynamic> json) {
    if (json == null) return null;
    return UserModel(
      id: json["id"],
      createdAt:
          json["createdAt"] == null ? null : DateTime.parse(json["createdAt"]),
      name: json["name"],
      avatar: json["avatar"],
    );
  }

  static List<UserModel> fromJsonList(List list) {
    if (list == null) return null;
    return list.map((item) => UserModel.fromJson(item)).toList();
  }

  ///this method will prevent the override of toString
  String userAsString() {
    return '#${this.id} ${this.name}';
  }

  ///this method will prevent the override of toString
  bool userFilterByCreationDate(String filter) {
    return this.createdAt.toString().contains(filter);
  }

  ///custom comparing function to check if two users are equal
  bool isEqual(UserModel model) {
    return this.id == model.id;
  }

  @override
  String toString() => name;
}