How to diagnose and fix the 2200L not_an_xml_document error code in Postgres.

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The 2200L error code in PostgreSQL, indicated by not_an_xml_document, suggests that there is an issue with an XML document that you are trying to process. This error typically arises when you attempt to perform an operation that expects a well-formed XML document, but the data provided is not valid XML.

Here are a few examples of how this error might occur and how you could diagnose and fix it:

  1. XML Input Validation:
    Before processing an XML document in PostgreSQL, ensure that the input is a well-formed XML document. You can validate this using tools or libraries outside of PostgreSQL, or by using PostgreSQL’s built-in XML functions.
   SELECT xmlelement(name "root", xmlattributes('value' as "attr"));

If the input is not a well-formed XML document, PostgreSQL will raise the 2200L error.

  1. Checking for Proper XML Format:
    When constructing XML content, make sure that you properly escape special characters and close all tags. An incorrectly formatted XML string can trigger this error. Example of incorrect XML:
   <note>
     <to>You</to>
     <from>Me<from> <!-- Missing '/' in the closing tag -->

Corrected XML:

   <note>
     <to>You</to>
     <from>Me</from>
   </note>
  1. Using PostgreSQL XML Functions:
    PostgreSQL provides functions to work with XML data types. If you’re trying to store or manipulate XML content, ensure you’re using these functions correctly. Example of storing XML data:
   INSERT INTO your_table (xml_column) VALUES (XMLPARSE(DOCUMENT 'your_xml_content'));

If ‘your_xml_content’ is not a well-formed XML, PostgreSQL will raise the 2200L error.

  1. Converting Text to XML:
    If you’re converting text to XML using XMLPARSE, make sure the text is a valid XML document.
   SELECT XMLPARSE(DOCUMENT your_text_column) FROM your_table;

If your_text_column contains invalid XML, this will result in the 2200L error.

To diagnose the issue, inspect the XML content that’s causing the error. Look for common issues such as missing closing tags, improperly escaped characters, and incorrect syntax. Once you identify the problem, correct the XML content and retry the operation.

Unfortunately, the search results provided do not give specific guidance on resolving the 2200L error in PostgreSQL. However, the general steps outlined above should help you diagnose and fix issues related to not well-formed XML documents in PostgreSQL.

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