FieldStart Class

public class FieldStart : FieldChar

Public Class FieldStart
	Inherits FieldChar

public ref class FieldStart : public FieldChar

type FieldStart =  
    class
        inherit FieldChar
    end

public void FieldCollection()
{
    // Create a new document and insert some fields
    Document doc = new Document();
    DocumentBuilder builder = new DocumentBuilder(doc);

    builder.InsertField(" DATE \\@ \"dddd, d MMMM yyyy\" ");
    builder.InsertField(" TIME ");
    builder.InsertField(" REVNUM ");
    builder.InsertField(" AUTHOR  \"John Doe\" ");
    builder.InsertField(" SUBJECT \"My Subject\" ");
    builder.InsertField(" QUOTE \"Hello world!\" ");
    doc.UpdateFields();

    // Get the collection that contains all the fields in a document
    FieldCollection fields = doc.Range.Fields;
    Assert.AreEqual(6, fields.Count);

    // Iterate over the field collection and print contents and type of every field using a custom visitor implementation
    FieldVisitor fieldVisitor = new FieldVisitor();

    using (IEnumerator<Field> fieldEnumerator = fields.GetEnumerator())
    {
        while (fieldEnumerator.MoveNext())
        {
            if (fieldEnumerator.Current != null)
            {
                fieldEnumerator.Current.Start.Accept(fieldVisitor);
                fieldEnumerator.Current.Separator?.Accept(fieldVisitor);
                fieldEnumerator.Current.End.Accept(fieldVisitor);
            }
            else
            {
                Console.WriteLine("There are no fields in the document.");
            }
        }
    }

    Console.WriteLine(fieldVisitor.GetText());

    // Get a field to remove itself
    fields[0].Remove();
    Assert.AreEqual(5, fields.Count);

    // Remove a field by reference
    Field lastField = fields[3];
    fields.Remove(lastField);
    Assert.AreEqual(4, fields.Count);

    // Remove a field by index
    fields.RemoveAt(2);
    Assert.AreEqual(3, fields.Count);

    // Remove all fields from the document
    fields.Clear();
    Assert.AreEqual(0, fields.Count);
}

/// <summary>
/// Document visitor implementation that prints field info.
/// </summary>
public class FieldVisitor : DocumentVisitor
{
    public FieldVisitor()
    {
        mBuilder = new StringBuilder();
    }

    /// <summary>
    /// Gets the plain text of the document that was accumulated by the visitor.
    /// </summary>
    public string GetText()
    {
        return mBuilder.ToString();
    }

    /// <summary>
    /// Called when a FieldStart node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldStart(FieldStart fieldStart)
    {
        mBuilder.AppendLine("Found field: " + fieldStart.FieldType);
        mBuilder.AppendLine("\tField code: " + fieldStart.GetField().GetFieldCode());
        mBuilder.AppendLine("\tDisplayed as: " + fieldStart.GetField().Result);

        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldSeparator node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldSeparator(FieldSeparator fieldSeparator)
    {
        mBuilder.AppendLine("\tFound separator: " + fieldSeparator.GetText());

        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldEnd node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldEnd(FieldEnd fieldEnd)
    {
        mBuilder.AppendLine("End of field: " + fieldEnd.FieldType);

        return VisitorAction.Continue;
    }

    private readonly StringBuilder mBuilder;
}

using System;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using Aspose.Words;
using Aspose.Words.Fields;
using NUnit.Framework;

namespace ApiExamples
{
    /// <summary>
    /// Shows how to replace hyperlinks in a Word document.
    /// </summary>
    public class ExReplaceHyperlinks : ApiExampleBase
    {
        /// <summary>
        /// Finds all hyperlinks in a Word document and changes their URL and display name.
        /// </summary>
        public void Fields()
        {
            // Specify your document name here
            Document doc = new Document(MyDir + "Hyperlinks.docx");

            // Hyperlinks in a Word documents are fields, select all field start nodes so we can find the hyperlinks
            NodeList fieldStarts = doc.SelectNodes("//FieldStart");
            foreach (FieldStart fieldStart in fieldStarts.OfType<FieldStart>())
            {
                if (fieldStart.FieldType.Equals(FieldType.FieldHyperlink))
                {
                    // The field is a hyperlink field, use the "facade" class to help to deal with the field
                    Hyperlink hyperlink = new Hyperlink(fieldStart);

                    // Some hyperlinks can be local (links to bookmarks inside the document), ignore these
                    if (hyperlink.IsLocal)
                        continue;

                    // The Hyperlink class allows to set the target URL and the display name 
                    // of the link easily by setting the properties
                    hyperlink.Target = NewUrl;
                    hyperlink.Name = NewName;
                }
            }

            doc.Save(ArtifactsDir + "ReplaceHyperlinks.Fields.docx");
        }

        private const string NewUrl = @"http://www.aspose.com";
        private const string NewName = "Aspose - The .NET & Java Component Publisher";
    }

    /// <summary>
    /// This "facade" class makes it easier to work with a hyperlink field in a Word document. 
    /// 
    /// A hyperlink is represented by a HYPERLINK field in a Word document. A field in Aspose.Words 
    /// consists of several nodes and it might be difficult to work with all those nodes directly. 
    /// Note this is a simple implementation and will work only if the hyperlink code and name 
    /// each consist of one Run only.
    /// 
    /// [FieldStart][Run - field code][FieldSeparator][Run - field result][FieldEnd]
    /// 
    /// The field code contains a String in one of these formats:
    /// HYPERLINK "url"
    /// HYPERLINK \l "bookmark name"
    /// 
    /// The field result contains text that is displayed to the user.
    /// </summary>
    internal class Hyperlink
    {
        internal Hyperlink(FieldStart fieldStart)
        {
            if (fieldStart == null)
                throw new ArgumentNullException("fieldStart");
            if (!fieldStart.FieldType.Equals(FieldType.FieldHyperlink))
                throw new ArgumentException("Field start type must be FieldHyperlink.");

            mFieldStart = fieldStart;

            // Find the field separator node
            mFieldSeparator = FindNextSibling(mFieldStart, NodeType.FieldSeparator);
            if (mFieldSeparator == null)
                throw new InvalidOperationException("Cannot find field separator.");

            // Find the field end node. Normally field end will always be found, but in the example document 
            // there happens to be a paragraph break included in the hyperlink and this puts the field end 
            // in the next paragraph. It will be much more complicated to handle fields which span several 
            // paragraphs correctly, but in this case allowing field end to be null is enough for our purposes
            mFieldEnd = FindNextSibling(mFieldSeparator, NodeType.FieldEnd);

            // Field code looks something like [ HYPERLINK "http:\\www.myurl.com" ], but it can consist of several runs
            string fieldCode = GetTextSameParent(mFieldStart.NextSibling, mFieldSeparator);
            Match match = gRegex.Match(fieldCode.Trim());
            mIsLocal = match.Groups[1].Length > 0; //The link is local if \l is present in the field code
            mTarget = match.Groups[2].Value;
        }

        /// <summary>
        /// Gets or sets the display name of the hyperlink.
        /// </summary>
        internal string Name
        {
            get { return GetTextSameParent(mFieldSeparator, mFieldEnd); }
            set
            {
                // Hyperlink display name is stored in the field result which is a Run 
                // node between field separator and field end
                Run fieldResult = (Run) mFieldSeparator.NextSibling;
                fieldResult.Text = value;

                // But sometimes the field result can consist of more than one run, delete these runs
                RemoveSameParent(fieldResult.NextSibling, mFieldEnd);
            }
        }

        /// <summary>
        /// Gets or sets the target url or bookmark name of the hyperlink.
        /// </summary>
        internal string Target
        {
            get
            {
                return mTarget;
            }
            set
            {
                mTarget = value;
                UpdateFieldCode();
            }
        }

        /// <summary>
        /// True if the hyperlinks target is a bookmark inside the document. False if the hyperlink is a url.
        /// </summary>
        internal bool IsLocal
        {
            get { return mIsLocal; }
            set
            {
                mIsLocal = value;
                UpdateFieldCode();
            }
        }

        private void UpdateFieldCode()
        {
            // Field code is stored in a Run node between field start and field separator
            Run fieldCode = (Run) mFieldStart.NextSibling;
            fieldCode.Text = string.Format("HYPERLINK {0}\"{1}\"", ((mIsLocal) ? "\\l " : ""), mTarget);

            // But sometimes the field code can consist of more than one run, delete these runs
            RemoveSameParent(fieldCode.NextSibling, mFieldSeparator);
        }

        /// <summary>
        /// Goes through siblings starting from the start node until it finds a node of the specified type or null.
        /// </summary>
        private static Node FindNextSibling(Node startNode, NodeType nodeType)
        {
            for (Node node = startNode; node != null; node = node.NextSibling)
            {
                if (node.NodeType.Equals(nodeType))
                    return node;
            }

            return null;
        }

        /// <summary>
        /// Retrieves text from start up to but not including the end node.
        /// </summary>
        private static string GetTextSameParent(Node startNode, Node endNode)
        {
            if ((endNode != null) && (startNode.ParentNode != endNode.ParentNode))
                throw new ArgumentException("Start and end nodes are expected to have the same parent.");

            StringBuilder builder = new StringBuilder();
            for (Node child = startNode; !child.Equals(endNode); child = child.NextSibling)
                builder.Append(child.GetText());

            return builder.ToString();
        }

        /// <summary>
        /// Removes nodes from start up to but not including the end node.
        /// Start and end are assumed to have the same parent.
        /// </summary>
        private static void RemoveSameParent(Node startNode, Node endNode)
        {
            if (endNode != null && startNode.ParentNode != endNode.ParentNode)
                throw new ArgumentException("Start and end nodes are expected to have the same parent.");

            Node curChild = startNode;
            while ((curChild != null) && (curChild != endNode))
            {
                Node nextChild = curChild.NextSibling;
                curChild.Remove();
                curChild = nextChild;
            }
        }

        private readonly Node mFieldStart;
        private readonly Node mFieldSeparator;
        private readonly Node mFieldEnd;
        private bool mIsLocal;
        private string mTarget;

        private static readonly Regex gRegex = new Regex(
            "\\S+" + // one or more non spaces HYPERLINK or other word in other languages
            "\\s+" + // one or more spaces
            "(?:\"\"\\s+)?" + // non capturing optional "" and one or more spaces, found in one of the customers files.
            "(\\\\l\\s+)?" + // optional \l flag followed by one or more spaces
            "\"" + // one apostrophe    
            "([^\"]+)" + // one or more chars except apostrophe (hyperlink target)
            "\"" // one closing apostrophe
        );
    }
}