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Schematron Validation

Last Updated: December 2025 | Version: 1.1.0

Schematron lets you create custom validation rules that go beyond what XSD schemas can check. It's perfect for validating business rules and data relationships.

Overview

While XSD schemas check the structure of your XML (which elements can appear where), Schematron checks the content and relationships:

XSD Checks Schematron Checks
Element names Data values
Element order Field relationships
Required fields Business rules
Data types Conditional requirements

Example Rules

  • "If status is 'approved', an approval date must be present"
  • "The total must equal the sum of all line items"
  • "Each ID must be unique in the document"

Toolbar

Button Shortcut Description
New - Create new Schematron file
Open - Open existing Schematron file
Save Ctrl+S Save current file
Save As Ctrl+Shift+S Save with new name
Add Rule Ctrl+R Add a new rule template
Add Favorite Ctrl+D Add to favorites
Favorites Ctrl+Shift+D Toggle favorites panel
Help F1 Show help

Code Editor

The Code tab provides a full-featured Schematron editor:

Editor Toolbar

Button Description
Load Schematron Open an existing file
New File Create empty Schematron
Save / Save As Save current file
New Rule Insert rule template
New Pattern Insert pattern template
Format Format/prettify the XML
Validate Check Schematron syntax
Test Rules Test against XML files

The sidebar provides helpful tools:

Quick Help

Shows Schematron basics: - <pattern> - Groups related rules together - <rule> - Defines context and conditions - <assert> - Tests a condition (must be true) - <report> - Reports a finding (when condition is true)

Common XPath expressions for Schematron rules.

Document Structure

Shows the structure of your current Schematron schema - patterns, rules, and assertions.

Rule Templates

Pre-built rule templates you can insert: - Required field check - Unique value check - Conditional requirement - Value comparison - Cross-reference validation

XPath Tester

Test XPath expressions against sample XML: 1. Enter an XPath expression 2. Click Test 3. See the result

Creating Schematron Rules

Basic Structure

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://purl.oclc.org/dsdl/schematron">
    <title>My Validation Rules</title>

    <pattern name="Invoice Validation">
        <rule context="invoice">
            <assert test="@date">
                Every invoice must have a date attribute.
            </assert>
            <assert test="customer">
                Every invoice must have a customer element.
            </assert>
        </rule>
    </pattern>
</schema>

Common Rule Patterns

Required Field

<rule context="order">
    <assert test="orderNumber">
        Order number is required.
    </assert>
</rule>

Conditional Requirement

<rule context="order">
    <assert test="not(@status='shipped') or shipDate">
        Shipped orders must have a ship date.
    </assert>
</rule>

Value Comparison

<rule context="order">
    <assert test="endDate >= startDate">
        End date must be after start date.
    </assert>
</rule>

Sum Validation

<rule context="invoice">
    <assert test="sum(item/price) = total">
        Total must equal sum of item prices.
    </assert>
</rule>

Unique Values

<rule context="items">
    <assert test="count(item) = count(distinct-values(item/@id))">
        All item IDs must be unique.
    </assert>
</rule>

Cross-Reference

<rule context="orderLine">
    <assert test="@productId = //product/@id">
        Product ID must reference an existing product.
    </assert>
</rule>

Testing Rules

Test Against XML Files

  1. Click Test Rules in the toolbar
  2. Select one or more XML files
  3. View validation results

Integration with XML Editor

Use Schematron validation directly in the XML Editor:

  1. Open an XML file in the XML Editor
  2. In the validation panel, select your Schematron file
  3. Errors are highlighted in the editor
  4. Click errors to jump to the problem location

Favorites Integration

Save frequently used Schematron files for quick access:

  • Add Favorite (Ctrl+D) - Save current file to favorites
  • Favorites (Ctrl+Shift+D) - Show/hide the favorites panel

XPath Reference

Common XPath expressions for Schematron rules:

Expression Description
. Current node
@attribute Attribute of current node
child::element Child element
parent::element Parent element
//element Any element in document
count(element) Count elements
string-length(.) Length of text content
contains(., 'text') Text contains substring
starts-with(., 'text') Text starts with
normalize-space(.) Normalized whitespace
sum(element) Sum of numeric values
distinct-values(element) Unique values

Supported Formats

Format Support
ISO Schematron (.sch) Full support
XSLT-based Schematron Full support

Keyboard Shortcuts

Shortcut Action
Ctrl+S Save file
Ctrl+Shift+S Save As
Ctrl+R Add new rule
Ctrl+D Add to favorites
Ctrl+Shift+D Toggle favorites
F1 Help

Tips

  • Start simple - Begin with basic rules and add complexity
  • Test both ways - Test with valid and invalid sample files
  • Clear messages - Write helpful error messages for users
  • Use patterns - Group related rules into patterns
  • XPath Tester - Use the sidebar to test expressions

Troubleshooting

Problem Solution
Rule not firing Check the context XPath matches elements
False positives Review your test condition logic
Namespace issues Add namespace declarations to schema
Performance slow Optimize complex XPath expressions
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