How to Validate QR Code Checksums and Apply Fault Tolerance in C#

using IronQr;
using IronSoftware.Drawing;

var reader = new QrReader();
IEnumerable<QrResult> results = reader.Read(new QrImageInput("damaged-label.png"));

// Reed-Solomon decoding is pass/fail — presence in results means valid checksum
if (!results.Any())
{
    // Decoding failed entirely — damage exceeded the error correction capacity
    Console.WriteLine("QR code could not be decoded. Consider re-scanning or using a higher error correction level at generation time.");
    return;
}

foreach (QrResult result in results)
{
    // Decoded successfully — validate the content matches expected format
    if (string.IsNullOrWhiteSpace(result.Value))
    {
        Console.WriteLine("QR decoded but produced an empty value.");
        continue;
    }

    Console.WriteLine($"Valid QR: {result.Value}");
}

Imports IronQr
Imports IronSoftware.Drawing

Dim reader As New QrReader()
Dim results As IEnumerable(Of QrResult) = reader.Read(New QrImageInput("damaged-label.png"))

' Reed-Solomon decoding is pass/fail — presence in results means valid checksum
If Not results.Any() Then
    ' Decoding failed entirely — damage exceeded the error correction capacity
    Console.WriteLine("QR code could not be decoded. Consider re-scanning or using a higher error correction level at generation time.")
    Return
End If

For Each result As QrResult In results
    ' Decoded successfully — validate the content matches expected format
    If String.IsNullOrWhiteSpace(result.Value) Then
        Console.WriteLine("QR decoded but produced an empty value.")
        Continue For
    End If

    Console.WriteLine($"Valid QR: {result.Value}")
Next

using IronQr;
using IronSoftware.Drawing;
using IronQr.Enum;

// Read from an image file with ML + classic scan (default)
var reader = new QrReader();
IEnumerable<QrResult> results = reader.Read(new QrImageInput("product-label.png"));

foreach (QrResult result in results)
{
    // Inspect the detected QR format
    Console.WriteLine($"Format: {result.QrType}");   // QRCode, MicroQRCode, or RMQRCode
    Console.WriteLine($"Value:  {result.Value}");

    // Url is non-null only if Value is a valid URI
    if (result.Url != null)
    {
        Console.WriteLine($"URI:    {result.Url.AbsoluteUri}");
    }

    // Corner coordinates for positional context
    Console.WriteLine($"Corners: {result.Points.Length} points detected");
}

// Read from a bitmap with ML-only mode for faster throughput
var bitmap = AnyBitmap.FromFile("camera-capture.jpg");
var fastResults = reader.Read(new QrImageInput(bitmap, QrScanMode.OnlyDetectionModel));

Imports IronQr
Imports IronSoftware.Drawing
Imports IronQr.Enum

' Read from an image file with ML + classic scan (default)
Dim reader As New QrReader()
Dim results As IEnumerable(Of QrResult) = reader.Read(New QrImageInput("product-label.png"))

For Each result As QrResult In results
    ' Inspect the detected QR format
    Console.WriteLine($"Format: {result.QrType}")   ' QRCode, MicroQRCode, or RMQRCode
    Console.WriteLine($"Value:  {result.Value}")

    ' Url is non-null only if Value is a valid URI
    If result.Url IsNot Nothing Then
        Console.WriteLine($"URI:    {result.Url.AbsoluteUri}")
    End If

    ' Corner coordinates for positional context
    Console.WriteLine($"Corners: {result.Points.Length} points detected")
Next

' Read from a bitmap with ML-only mode for faster throughput
Dim bitmap As AnyBitmap = AnyBitmap.FromFile("camera-capture.jpg")
Dim fastResults = reader.Read(New QrImageInput(bitmap, QrScanMode.OnlyDetectionModel))

using IronQr;
using IronSoftware.Drawing;
using System.Collections.Generic;
using System.Linq;

public static class QrValidator
{
    public static List<QrResult> GetValidResults(
        string imagePath,
        QrEncoding? expectedFormat = null)
    {
        var reader = new QrReader();
        IEnumerable<QrResult> results = reader.Read(new QrImageInput(imagePath));

        // Guard: no QR codes detected
        if (!results.Any())
            return new List<QrResult>();

        return results
            .Where(r => !string.IsNullOrWhiteSpace(r.Value))
            .Where(r => expectedFormat == null || r.QrType == expectedFormat)
            .ToList();
    }
}

// Usage — only accept standard QR codes with non-empty values
var validated = QrValidator.GetValidResults(
    "shipping-manifest.png",
    expectedFormat: QrEncoding.QRCode);

if (validated.Count == 0)
{
    Console.WriteLine("No valid QR codes found for processing.");
    return;
}

foreach (var qr in validated)
{
    // Safe for downstream: value is non-empty, format is verified
    SendToInventoryApi(qr.Value, qr.Url?.AbsoluteUri);
}

Imports IronQr
Imports IronSoftware.Drawing
Imports System.Collections.Generic
Imports System.Linq

Public Module QrValidator
    Public Function GetValidResults(
        imagePath As String,
        Optional expectedFormat As QrEncoding? = Nothing) As List(Of QrResult)

        Dim reader As New QrReader()
        Dim results As IEnumerable(Of QrResult) = reader.Read(New QrImageInput(imagePath))

        ' Guard: no QR codes detected
        If Not results.Any() Then
            Return New List(Of QrResult)()
        End If

        Return results _
            .Where(Function(r) Not String.IsNullOrWhiteSpace(r.Value)) _
            .Where(Function(r) expectedFormat Is Nothing OrElse r.QrType = expectedFormat) _
            .ToList()
    End Function
End Module

' Usage — only accept standard QR codes with non-empty values
Dim validated = QrValidator.GetValidResults(
    "shipping-manifest.png",
    expectedFormat:=QrEncoding.QRCode)

If validated.Count = 0 Then
    Console.WriteLine("No valid QR codes found for processing.")
    Return
End If

For Each qr In validated
    ' Safe for downstream: value is non-empty, format is verified
    SendToInventoryApi(qr.Value, qr.Url?.AbsoluteUri)
Next qr