How to diagnose and fix the 2200M invalid_xml_document error code in Postgres.

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The 2200M error code in PostgreSQL indicates an “invalid XML document” issue. This error arises when you try to store, manipulate, or query XML data that is not well-formed according to XML standards. To diagnose and fix this issue, you should check the following:

  1. Well-Formedness:
    Ensure that the XML content is well-formed. This means that it should have a proper opening and closing tags, correctly nested elements, and no syntax errors. For example, <tag>value</wrongtag> is incorrect and should be <tag>value</tag>.
  2. Proper Encoding:
    The XML encoding should match the declared encoding in the XML document. If the XML declaration states <?xml version="1.0" encoding="UTF-8"?>, the content should be in UTF-8 encoding.
  3. Escape Special Characters:
    Special characters like &, <, and > should be escaped as &amp;, &lt;, and &gt; respectively within the XML content.
  4. Valid Characters:
    Ensure that the XML document does not contain invalid characters. Characters like null 0x00 are not allowed in XML 1.0 documents.
  5. Size Limitations:
    PostgreSQL has a limitation on the size of XML documents it can process. If your document is exceptionally large, consider breaking it into smaller parts before processing.
  6. Use XMLPARSE Function:
    PostgreSQL provides the XMLPARSE function to parse a string as XML. This function will raise an error if the string is not well-formed XML.
   SELECT XMLPARSE(DOCUMENT '<tag>content</tag>');
  1. Schema Validation (if applicable):
    If you’re using an XML schema to validate the document’s structure, ensure the document adheres to the schema.

Here are some examples of diagnosing and fixing common XML errors:

  • Example 1: Fixing Mismatched Tags Incorrect XML:
  <root>
    <child>Content</child2>
  </root>

Corrected XML:

  <root>
    <child>Content</child>
  </root>

PostgreSQL code to store corrected XML:

  INSERT INTO your_table(xml_column) VALUES (XMLPARSE(DOCUMENT '<root><child>Content</child></root>'));
  • Example 2: Escaping Special Characters Incorrect XML:
  <root>
    <child>Content with & and <</child>
  </root>

Corrected XML:

  <root>
    <child>Content with &amp; and &lt;</child>
  </root>

PostgreSQL code to store corrected XML:

  INSERT INTO your_table(xml_column) VALUES (XMLPARSE(DOCUMENT '<root><child>Content with &amp; and &lt;</child></root>'));
  • Example 3: Removing Invalid Characters Incorrect XML containing a null character:
  <root>InvalidCharHere</root>

Corrected XML with the null character removed:

  <root>InvalidCharHere</root>

PostgreSQL code to remove invalid characters and store corrected XML:

  INSERT INTO your_table(xml_column) VALUES (XMLPARSE(DOCUMENT REPLACE('<root>InvalidCharHere</root>', E'\u0000', '')));

If you encounter persistent issues with XML content, consider using tools or libraries that can validate and format XML documents before they are processed by PostgreSQL. Always back up your data before performing operations that modify large amounts of data.

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