在元素中包含 XML CDATA

Question

UPDATE: Added more detail per request

I am trying to create an xml configuration file for my application. The file contains a list of criteria to search and replace in an html document. The problem is, I need to search for character strings like &nbsp . I do not want my code to read the decoded item, but the text itself.

Admitting to being very new to XML, I did make some attempts at meeting the requirements. I read a load of links here on Stackoverflow regarding CDATA and ATTRIBUTES and so on, but the examples here (and elsewhere) seem to focus on creating one single line in an xml file, not multiple.

Here is one of many attempts I have made to no avail:

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE item [
  <!ELEMENT item (id, replacewith)>
  <!ELEMENT id (#CDATA)>
  <!ELEMENT replacewith (#CDATA)>
  ]>
]>
<item id=" " replacewith="&nbsp;">Non breaking space</item>
<item id="&#8209;" replacewith="-">Non breaking hyphen</item>

This document gives me a number of errors, including:

• In the DOCTYPE, I get errors like <!ELEMENT id (#CDATA)> . In the CDATA area, Visual Studio informs me it is expecting a ',' or '|'.
• ]> gives me an error of invalid token at the root of the document .
• And of course, after the second <item entry, I get an error stating XML document cannot contain multiple root level elements .

How can I write an xml file that includes multiple items and allows me to store and retrieve the text within the element, rather than the interpreted characters?

If it helps any, I am using .Net, C#, and Visual Studio.

EDIT: The purpose of this xml file is to provide my code with a list of things to search and replace in an html file. The xml file simply contains a list of what to search for and what to replace with .

Here is the file I have in place right now:

<?xml version="1.0" encoding="utf-8" ?>
<Items>
  <item id="&#8209;" replacewith="-">Non breaking hyphen</item>
  <item id=" " replacewith="&nbsp;">Non breaking hyphen</item>
</Items>

Using the first as an example, I want to read the text &#8209 but instead when I read this, I get - because that is what the code represents.

Any help or pointers you can give would be helpful.

Answer 1

To elaborate on my comment: XML acts like HTML due to the reserved characters. An ampersand prefixes keywords or character codes to translate into a literal string when read in with any type of parser (browser, XML reader, etc).

The easiest way to escape the values to make sure they are read back in as the literal that you want is to put them in as if you were encoding it for web. For example, to create your XML document, I did this:

     XmlDocument xmlDoc = new XmlDocument();
     XmlElement xmlItem;
     XmlAttribute xmlAttr;
     XmlText xmlText;

     // Declaration
     XmlDeclaration xmlDec = xmlDoc.CreateXmlDeclaration("1.0", "UTF-8", null);
     XmlElement xmlRoot = xmlDoc.DocumentElement;
     xmlDoc.InsertBefore(xmlDec, xmlRoot);

     // Items
     XmlElement xmlItems = xmlDoc.CreateElement(string.Empty, "Items", string.Empty);
     xmlDoc.AppendChild(xmlItems);

     // Item #1
     xmlItem = xmlDoc.CreateElement(string.Empty, "item", string.Empty);
     xmlAttr = xmlDoc.CreateAttribute(string.Empty, "id", string.Empty);
     xmlAttr.Value = "‑";
     xmlItem.Attributes.Append(xmlAttr);
     xmlAttr = xmlDoc.CreateAttribute(string.Empty, "replacewith", string.Empty);
     xmlAttr.Value = "-";
     xmlItem.Attributes.Append(xmlAttr);
     xmlText = xmlDoc.CreateTextNode("Non breaking hyphen");
     xmlItem.AppendChild(xmlText);

     xmlItems.AppendChild(xmlItem);

     // Item #2
     xmlItem = xmlDoc.CreateElement(string.Empty, "item", string.Empty);
     xmlAttr = xmlDoc.CreateAttribute(string.Empty, "id", string.Empty);
     xmlAttr.Value = " ";
     xmlItem.Attributes.Append(xmlAttr);
     xmlAttr = xmlDoc.CreateAttribute(string.Empty, "replacewith", string.Empty);
     xmlAttr.Value = " ";
     xmlItem.Attributes.Append(xmlAttr);
     xmlText = xmlDoc.CreateTextNode("Non breaking hyphen");
     xmlItem.AppendChild(xmlText);

     xmlItems.AppendChild(xmlItem);

     // For formatting
     StringBuilder xmlBuilder = new StringBuilder();
     XmlWriterSettings xmlSettings = new XmlWriterSettings
     {
        Indent = true,
        IndentChars = "  ",
        NewLineChars = "\r\n",
        NewLineHandling = NewLineHandling.Replace
     };
     using (XmlWriter writer = XmlWriter.Create(xmlBuilder, xmlSettings))
     {
        xmlDoc.Save(writer);
     }

     xmlOutput.Text = xmlBuilder.ToString();

Notice that I put in your id values with what you are expecting. Now, look at how it gets encoded:

<?xml version="1.0" encoding="utf-16"?>
<Items>
  <item id="&amp;#8209;" replacewith="-">Non breaking hyphen</item>
  <item id=" " replacewith="&amp;nbsp;">Non breaking hyphen</item>
</Items>

The only difference between yours and this one is that the ampersand was encoded as & and the rest remained as a string literal. This is normal behavior for XML. When you read it back in, it will come back as the literal ‑ and   .