bangladesh_geo_postcode

Offline Bangladesh geographic postcode lookup for Flutter. Supports Division > District > Thana > Postcode navigation in both Bangla and English.

Uses Protocol Buffers for fast binary loading — no database, no API, fully offline.

Features

Division / District / Thana / Postcode hierarchy
Bangla & English language support
O(1) postcode search (supports both 1206 and ১২০৬)
One-time protobuf load, in-memory cache
No network, no SQLite, no external dependency

Getting Started

1. Add dependency

dependencies:
  bangladesh_geo_postcode: ^0.0.1

2. Initialise at app startup

import 'package:bangladesh_geo_postcode/bangladesh_geo_postcode.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await LocationCache.instance.load();
  runApp(MyApp());
}

Usage

const service = LocationService();

// Get all divisions
final divisions = service.getDivisions(Language.en);
final divisionsBn = service.getDivisions(Language.bn);

// Get districts in a division
final districts = service.getDistricts('Dhaka', Language.en);

// Get thanas in a district
final thanas = service.getThanas('Dhaka', 'Dhaka', Language.en);

// Search by postcode (English or Bangla)
final result = service.searchByPostcode('1206');
final resultBn = service.searchByPostcode('১২০৬');

// Access location fields
if (result != null) {
  print(result.divisionEn);   // Dhaka
  print(result.districtBn);   // ঢাকা
  print(result.thanaEn);      // Dhaka
  print(result.postcodeEn);   // 1206
  print(result.postcodeBn);   // ১২০৬
  print(result.subofficeEn);  // Dhaka Cantonment--TSO
}

// Get all postcodes in a division
final divCodes = service.getPostcodesByDivision('Dhaka');

// Get all postcodes in a district
final distCodes = service.getPostcodesByDistrict('Dhaka', 'Dhaka');

// Get all postcodes in a thana
final thanaCodes = service.getPostcodesByThana('Dhaka', 'Dhaka', 'Dhamrai');

Bangla Postcode Search

The postcode normalizer automatically converts Bangla digits to English for matching:

// Both return the same result
service.searchByPostcode('1206');
service.searchByPostcode('১২০৬');

You can also use the normalizer directly:

final normalized = normalizePostcode('১২০৬'); // "1206"

API Reference

LocationCache

Method	Description
`LocationCache.instance.load()`	Load data into memory (call once at startup)
`LocationCache.instance.isLoaded`	Whether data has been loaded

LocationService

Method	Returns	Description
`getDivisions(Language)`	`List<String>`	All unique division names
`getDistricts(division, Language)`	`List<String>`	Districts within a division
`getThanas(division, district, Language)`	`List<String>`	Thanas within a district
`searchByPostcode(postcode)`	`Location?`	First match for a postcode
`searchAllByPostcode(postcode)`	`List<Location>`	All matches for a postcode
`getPostcodesByDivision(division)`	`List<Location>`	All locations in a division
`getPostcodesByDistrict(division, district)`	`List<Location>`	All locations in a district
`getPostcodesByThana(division, district, thana)`	`List<Location>`	All locations in a thana
`getAll()`	`List<Location>`	Every loaded location

Location Fields

Field	Type	Description
`divisionEn` / `divisionBn`	`String`	Division name
`districtEn` / `districtBn`	`String`	District name
`thanaEn` / `thanaBn`	`String`	Thana name
`subofficeEn` / `subofficeBn`	`String`	Sub-office name
`postcodeEn` / `postcodeBn`	`String`	Postcode

Language

enum Language { en, bn }

License

MIT