indian_input_formatter

Production-grade, cursor-safe Indian input formatters and validators for Flutter.

Format Indian data as users type — Aadhaar, PAN, GSTIN, IFSC, UPI, +91 Phone, PIN Code, and INR Currency (lakhs & crores).

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Features

• 🎯 Cursor-Safe: Cursor position is preserved accurately during typing, middle insertions, deletions, and pasting.
• ⚡ Zero External Dependencies: Pure Flutter and Dart with zero third-party packages.
• 🛡️ Mathematical Validation: Official Verhoeff checksum for Aadhaar and official Luhn Mod-36 algorithm for GSTIN.
• 🧩 Drop-in Widget: Preconfigured IndianTextFormField for instant form setup.
• 🌐 Full Cross-Platform & WASM: Supports Android, iOS, Web (including WASM), Windows, macOS, and Linux.

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Getting Started

Add indian_input_formatter to your pubspec.yaml:

dependencies:
  indian_input_formatter: ^0.1.0

Import the package:

import 'package:indian_input_formatter/indian_input_formatter.dart';

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Supported Formatters & Validators

Field	Formatter	Formatted Pattern	Validator
Aadhaar	AadhaarInputFormatter()	1234 5678 9012	IndianValidators.aadhaar (Verhoeff)
PAN Card	PanInputFormatter()	ABCDE1234F	IndianValidators.pan
GSTIN	GstinInputFormatter()	27AAAPZ2318J1ZI	IndianValidators.gstin (Mod-36)
IFSC Code	IfscInputFormatter()	HDFC0001234	IndianValidators.ifsc
Mobile (+91)	IndianPhoneInputFormatter()	+91 98765 43210	IndianValidators.phone
PIN Code	PincodeInputFormatter()	560001	IndianValidators.pincode
UPI ID	UpiIdInputFormatter()	username@bank	IndianValidators.upi
INR Currency	IndianCurrencyInputFormatter()	₹12,34,567.50	—

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Usage Examples

1. Using IndianTextFormField (Simplest)

Use the built-in IndianTextFormField to quickly create preconfigured fields with appropriate formatters, validators, keyboard types, and labels:

// Aadhaar field
IndianTextFormField(
  type: IndianFieldType.aadhaar,
)

// Currency field (INR)
IndianTextFormField(
  type: IndianFieldType.currency,
)

// Mobile number field
IndianTextFormField(
  type: IndianFieldType.phone,
)

2. Using Formatters with Standard TextFormField

All formatters extend Flutter's TextInputFormatter and can be composed with any TextField or TextFormField:

Aadhaar Formatter

TextFormField(
  inputFormatters: const [AadhaarInputFormatter()],
  validator: IndianValidators.aadhaar,
  keyboardType: TextInputType.number,
  decoration: const InputDecoration(labelText: 'Aadhaar Number'),
)

Indian Currency Formatter (Lakh / Crore Grouping)

TextFormField(
  inputFormatters: const [
    IndianCurrencyInputFormatter(
      showSymbol: true, // Default: true (₹)
      decimalPlaces: 2, // Default: 2
    ),
  ],
  keyboardType: const TextInputType.numberWithOptions(decimal: true),
  decoration: const InputDecoration(labelText: 'Amount'),
)

Phone Formatter (+91 Prefix)

Automatically adds +91 prefix and handles pasting of +919876543210, 09876543210, or 9876543210:

TextFormField(
  inputFormatters: const [IndianPhoneInputFormatter()],
  validator: IndianValidators.phone,
  keyboardType: TextInputType.phone,
  decoration: const InputDecoration(labelText: 'Mobile Number'),
)

GSTIN & PAN Formatters

Auto-uppercases input and limits characters:

TextFormField(
  inputFormatters: const [GstinInputFormatter()],
  validator: IndianValidators.gstin,
  decoration: const InputDecoration(labelText: 'GSTIN'),
)

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Standalone Validators

You can also use IndianValidators independently in your business logic or custom forms:

// Returns null if valid, or an error String if invalid:
String? error = IndianValidators.aadhaar('1234 5678 9012');
String? panError = IndianValidators.pan('ABCDE1234F');
String? gstinError = IndianValidators.gstin('27AAAPZ2318J1ZI');

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Example App

Check out the example/ directory for a complete Flutter application demonstrating all formatters and form validation in action.

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License

This project is licensed under the MIT License - see the LICENSE file for details.