Xml and Schema Validator

1. Introduction

First, I decided to write this article to share some of intuited knowledge, try to help and demonstrate how it is possible to develop a simple and generic module for validating XML files with their respective schema files.

 

2. Project Structure

 

3. XmlAndSchemaValidator Class Library Source Code

using System;
using System.Xml;
using System.Xml.Schema;
using System.IO;
using System.Text;

namespace XmlAndSchemaValidator
{
    public class Validator
    {
        #region Attributes
        private System.Xml.XmlTextReader _XmlTextReader = null;
        private System.Xml.XmlReader _XmlReader = null;
        private System.Xml.XmlReaderSettings _XmlReaderSettings = null;
        private System.Xml.XmlParserContext _XmlParserContext = null;
        private System.Xml.Schema.XmlSchemaSet _XmlSchemaSet = null;
        private string _ValidationError = string.Empty;
        #endregion

        #region Object Constructor
        public Validator()
        {
            this._XmlSchemaSet = new System.Xml.Schema.XmlSchemaSet();
            this._XmlParserContext = new System.Xml.XmlParserContext(null, null, "", XmlSpace.None);

            ValidationEventHandler _ValidationEventHandler = new ValidationEventHandler(ValidationErrors);
        }
        #endregion

        #region Validate
        // This Method will validate a Xml File
        public string Validate(Int32 _EncodingType, FileInfo _XmlFile, XmlNodeType _XmlNodeType, string _Namespace, string _URI)
        {
            System.Text.UTF8Encoding _UTF8Encoding = new System.Text.UTF8Encoding();
            System.Text.UTF32Encoding _UTF32Encoding = new System.Text.UTF32Encoding();
            System.Text.Encoding _Encoding = System.Text.Encoding.GetEncoding("ISO-8859-1");
            Int32 _StartIndex = 0;
            Int32 _EndIndex = 0;
            string _XmlString = string.Empty;
            Byte[] _Buffer = null;
            FileStream _FileStream = null;

            try
            {
                // Verifies if the Xml file exists on the filesystem
                if (_XmlFile.Exists)
                {
                    try
                    {
                        _FileStream = _XmlFile.OpenRead();
                        _Buffer = new Byte[_FileStream.Length];

                        _FileStream.Read(_Buffer, 0, _Buffer.Length);

                        // Read the Xml file content with a pre-determinated encoding
                        switch (_EncodingType.ToString())
                        {
                            case "1":
                                _XmlString = _UTF8Encoding.GetString(_Buffer);
                                break;

                            case "2":
                                _XmlString = _UTF32Encoding.GetString(_Buffer);
                                break;

                            case "3":
                                _XmlString = _Encoding.GetString(_Buffer);
                                break;
                        }

                        _XmlString = _XmlString.Replace("\r", "");
                        _XmlString = _XmlString.Replace("\n", "");
                        _XmlString = _XmlString.Replace("\t", "");

                        _FileStream.Close();
                    }
                    catch
                    {
                        _FileStream.Close();
                    }
                }

                // Add the NameSpace and the Schema file for validation
                this._XmlSchemaSet.Add(_Namespace, _URI);

                // Creates the XmlTextReader based on the Xml file content
                this._XmlTextReader = new XmlTextReader(_XmlString, _XmlNodeType, this._XmlParserContext);
                this._XmlTextReader.Read();

                // Setup XmlReaderSettings
                this._XmlReaderSettings = new System.Xml.XmlReaderSettings();
                this._XmlReaderSettings.ValidationType = ValidationType.Schema;
                this._XmlReaderSettings.IgnoreComments = true;
                this._XmlReaderSettings.IgnoreWhitespace = true;

                // Add the NameSpace and the Schema file for validation
                this._XmlReaderSettings.Schemas.Add(_Namespace, _URI);

                // ConformanceLevel Auto indicates that the XML writer should determine the level of conformance
                this._XmlReaderSettings.ConformanceLevel = ConformanceLevel.Auto;

                // Creates a XmlReader based on the information gathered on XmlTextReader and assumes the XmlReaderSettings
                this._XmlReader = System.Xml.XmlReader.Create(this._XmlTextReader, this._XmlReaderSettings);

                // This step will read all Xml file and throw an exception when the
                // xml file is not valid
                while (this._XmlReader.Read())
                {

                }
            }
            catch (XmlException _XmlException)
            {
                this._ValidationError = _XmlException.Message;
            }
            catch (XmlSchemaException _XmlSchemaException)
            {
                this._ValidationError = _XmlSchemaException.Message;
            }
            catch (Exception _Exception)
            {
                this._ValidationError = _Exception.Message;
            }

            // Manipulate the error message
            if (this._ValidationError.Trim().ToString() != string.Empty)
            {
                _StartIndex = this._ValidationError.IndexOf("An error occurred at");
                _EndIndex = this._ValidationError.Length - (this._ValidationError.Length - _StartIndex);

                if (_StartIndex >= 0)
                    this._ValidationError = this._ValidationError.Substring(0, _EndIndex);
            }

            return this._ValidationError;
        }

        // This Method will validate a Xml String
        public string Validate(string _XmlString, XmlNodeType _XmlNodeType, string _Namespace, string _URI)
        {
            Int32 _StartIndex = 0;
            Int32 _EndIndex = 0;

            try
            {
                // Add the NameSpace and the Schema file for validation
                this._XmlSchemaSet.Add(_Namespace, _URI);

                // Creates the XmlTextReader based on the Xml file content
                this._XmlTextReader = new XmlTextReader(_XmlString, _XmlNodeType, this._XmlParserContext);
                this._XmlTextReader.Read();

                // Setup XmlReaderSettings
                this._XmlReaderSettings = new System.Xml.XmlReaderSettings();
                this._XmlReaderSettings.ValidationType = ValidationType.Schema;
                this._XmlReaderSettings.IgnoreComments = true;
                this._XmlReaderSettings.IgnoreWhitespace = true;

                // Add the NameSpace and the Schema file for validation
                this._XmlReaderSettings.Schemas.Add(_Namespace, _URI);

                // ConformanceLevel Auto indicates that the XML writer should determine the level of conformance
                this._XmlReaderSettings.ConformanceLevel = ConformanceLevel.Auto;

                // Creates a XmlReader based on the information gathered on XmlTextReader and assumes the XmlReaderSettings
                this._XmlReader = System.Xml.XmlReader.Create(this._XmlTextReader, this._XmlReaderSettings);

                // This step will read all Xml file and throw an exception when the
                // xml file is not valid
                while (this._XmlReader.Read())
                {

                }
            }
            catch (XmlException _XmlException)
            {
                this._ValidationError = _XmlException.Message;
            }
            catch (XmlSchemaException _XmlSchemaException)
            {
                this._ValidationError = _XmlSchemaException.Message;
            }
            catch (Exception _Exception)
            {
                this._ValidationError = _Exception.Message;
            }

            // Manipulate the error message
            if (this._ValidationError.Trim().ToString() != string.Empty)
            {
                _StartIndex = this._ValidationError.IndexOf("An error occurred at");
                _EndIndex = this._ValidationError.Length-(this._ValidationError.Length-_StartIndex);

                this._ValidationError = this._ValidationError.Substring(0,_EndIndex);
            }

            return this._ValidationError;
        }
        #endregion

        #region Validation Errors
        public static void ValidationErrors(object sender, ValidationEventArgs args)
        {

        }
        #endregion
    }
}

4. XmlAndSchemaValidator Tester Application Validation Windows Form Source Code

using System;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace XmlAndSchemaValidator.Tester
{
    public partial class ValidationForm : Form
    {
        #region Attibutes
        private DialogResult _DialogResult;
        private XmlAndSchemaValidator.Validator _Validator = null;
        #endregion

        #region Object Constructor
        public ValidationForm()
        {
            InitializeComponent();
        }
        #endregion

        #region Events
        #region bntSelectXmlFile_Click
        private void bntSelectXmlFile_Click(object sender, EventArgs e)
        {
            string _ErrorMsg = string.Empty;

            try
            {
                this.txtXmlFile.Text = string.Empty;

                this.ofdXmlFile = new OpenFileDialog();
                this.ofdXmlFile.Filter = "Xml Files (*.xml)|*.xml|All Files (*.*)|*.*";
                this.ofdXmlFile.Title = "Select Xml file for Schema validation";
                this._DialogResult = this.ofdXmlFile.ShowDialog();

                if (this._DialogResult == System.Windows.Forms.DialogResult.OK)
                {
                    if (this.ofdXmlFile.FileName != string.Empty)
                    {
                        this.txtXmlFile.Text = this.ofdXmlFile.FileName.ToString().Trim();
                    }
                }
            }
            catch (Exception _Exception)
            {
                _ErrorMsg = string.Empty;
                _ErrorMsg = "*************** Error ***************" + "\r\n";
                _ErrorMsg = _ErrorMsg + " -> Event: bntSelectXmlFile_Click\r\n";
                _ErrorMsg = _ErrorMsg + " -> Message: " + _Exception.Message.ToString() + "\r\n";
                _ErrorMsg = _ErrorMsg + " -> Stack Trace: " + _Exception.StackTrace.ToString() + "\r\n";

                if (_Exception.InnerException != null)
                {
                    _ErrorMsg = _ErrorMsg + " -> InnerException Message: " + _Exception.InnerException.Message.ToString() + "\r\n";
                    _ErrorMsg = _ErrorMsg + " -> InnerException Stack Trace: " + _Exception.InnerException.StackTrace.ToString() + "\r\n";
                }

                _ErrorMsg = "*************************************";

                MessageBox.Show(_ErrorMsg, "XmlAndSchemaValidator", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
        #endregion

        #region bntSelectXsdFile_Click
        private void bntSelectXsdFile_Click(object sender, EventArgs e)
        {
            string _ErrorMsg = string.Empty;

            try
            {
                this.txtXsdFile.Text = string.Empty;

                this.ofdXsdFile = new OpenFileDialog();
                this.ofdXsdFile.Filter = "Xsd Files (*.Xsd)|*.Xsd|All Files (*.*)|*.*";
                this.ofdXsdFile.Title = "Select Xsd file to use in validation";
                this._DialogResult = this.ofdXsdFile.ShowDialog();

                if (this._DialogResult == System.Windows.Forms.DialogResult.OK)
                {
                    if (this.ofdXsdFile.FileName != string.Empty)
                    {
                        this.txtXsdFile.Text = this.ofdXsdFile.FileName.ToString().Trim();
                    }
                }
            }
            catch (Exception _Exception)
            {
                _ErrorMsg = string.Empty;
                _ErrorMsg = "*************** Error ***************" + "\r\n";
                _ErrorMsg = _ErrorMsg + " -> Event: bntSelectXsdFile_Click\r\n";
                _ErrorMsg = _ErrorMsg + " -> Message: " + _Exception.Message.ToString() + "\r\n";
                _ErrorMsg = _ErrorMsg + " -> Stack Trace: " + _Exception.StackTrace.ToString() + "\r\n";

                if (_Exception.InnerException != null)
                {
                    _ErrorMsg = _ErrorMsg + " -> InnerException Message: " + _Exception.InnerException.Message.ToString() + "\r\n";
                    _ErrorMsg = _ErrorMsg + " -> InnerException Stack Trace: " + _Exception.InnerException.StackTrace.ToString() + "\r\n";
                }

                _ErrorMsg = "*************************************";

                MessageBox.Show(_ErrorMsg, "XmlAndSchemaValidator", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
        #endregion

        #region bntValidate_Click
        private void bntValidate_Click(object sender, EventArgs e)
        {
            string _ErrorMsg = string.Empty;
            string _ValidatorErrorMsg = string.Empty;
            FileInfo _FileInfo = null;

            try
            {
                this.txtValidationResult.Text = string.Empty;

                _FileInfo = new FileInfo(this.txtXmlFile.Text);
                this._Validator = new XmlAndSchemaValidator.Validator();
                _ValidatorErrorMsg = this._Validator.Validate(3, _FileInfo, System.Xml.XmlNodeType.Element, this.txtTargetNameSpace.Text, this.txtXsdFile.Text);

                if (_ValidatorErrorMsg != string.Empty)
                {
                    _ErrorMsg = string.Empty;
                    _ErrorMsg = "*************** Validation Error ***************" + "\r\n";
                    _ErrorMsg = _ErrorMsg + "Validation Message: " + _ValidatorErrorMsg.ToString() + "\r\n";
                    _ErrorMsg = _ErrorMsg + "************************************************";

                    this.txtValidationResult.AppendText(_ErrorMsg);
                }
                else
                {
                    _ErrorMsg = string.Empty;
                    _ErrorMsg = "*************** Validation Sucess ***************" + "\r\n";
                    _ErrorMsg = _ErrorMsg + "No Validation error ocorred!!!\r\n";
                    _ErrorMsg = _ErrorMsg + "************************************************";

                    this.txtValidationResult.AppendText(_ErrorMsg);
                }
            }
            catch (Exception _Exception)
            {
                _ErrorMsg = string.Empty;
                _ErrorMsg = "*************** Error ***************" + "\r\n";
                _ErrorMsg = _ErrorMsg + " -> Event: bntValidate_Click\r\n";
                _ErrorMsg = _ErrorMsg + " -> Message: " + _Exception.Message.ToString() + "\r\n";
                _ErrorMsg = _ErrorMsg + " -> Stack Trace: " + _Exception.StackTrace.ToString() + "\r\n";

                if (_Exception.InnerException != null)
                {
                    _ErrorMsg = _ErrorMsg + " -> InnerException Message: " + _Exception.InnerException.Message.ToString() + "\r\n";
                    _ErrorMsg = _ErrorMsg + " -> InnerException Stack Trace: " + _Exception.InnerException.StackTrace.ToString() + "\r\n";
                }

                _ErrorMsg = _ErrorMsg + "*************************************";

                MessageBox.Show(_ErrorMsg, "XmlAndSchemaValidator", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
        #endregion
        #endregion
    }
}

Finally the tester application should behave like this:

 

 

5. Conclution

Thank you for your care provided during reading my article and I hope you have been helped in some way.