Schema Support¶

Version: 2.1.0

FreeXmlToolkit supports different schema formats for validating your XML and JSON files. This page explains what's supported and what isn't.

Overview¶

Schemas define rules for your XML documents - what elements are allowed, what order they should be in, and what values they can contain.

Supported Schema Formats¶

XSD (XML Schema Definition)¶

XSD Support The Validation panel - an XML document checked against its bound XSD schema

Full Support - The main schema format used for XML validation.

Feature	Description
Validation	Check if XML files follow schema rules
Auto-Completion	Get suggestions while typing based on schema
Auto-Detection	Schema is found automatically from XML files
Documentation	Generate readable documentation from schemas
Sample Data	Create test XML files from schema definitions
Visual Display	See schema structure as diagrams

What You Can Define: - Elements and their order - Required and optional fields - Data types (text, numbers, dates) - Allowed values - Documentation

Schematron¶

Schematron Support A Schematron rules file (.sch) open as a normal document in the editor

Business Rules - For validation rules that go beyond structure.

Feature	Description
Custom Rules	Write your own validation logic
Real-time Checking	See errors as you edit
Clear Messages	Define helpful error messages
Flexible Rules	Apply different rules in different situations

Best For: - "If field A is filled, then field B must also be filled" - "The total must equal the sum of all items" - "Each ID must be unique in the document"

JSON Schema¶

Full Support (for JSON documents) - The standard schema format for validating JSON files.

Feature	Description
Validation	Check if JSON files follow schema rules
Auto-Detection	A schema referenced by the document's `$schema` member is bound automatically
Manual Binding	Bind a schema via the status bar indicator, the Validation panel, or drag & drop
Line Numbers	Each problem points to the offending line in your document
Dialects	Draft-07, 2019-09, and 2020-12

JSON Schemas bind and validate the same way XSD schemas do for XML - see the JSON Editor page for details.

XML Catalogs (OASIS)¶

Full Support - Register one or more OASIS catalog.xml files in the Schema Library's Catalogs tab to resolve system, public, uri, rewriteSystem, rewriteURI, nextCatalog and xml:base entries when the toolkit looks up an xs:import/xs:include or a schema reference by system ID. During validation the lookup tries the system identifier, then the public identifier (public entries), then the namespace, so public entries resolve schemas too.

Not Supported¶

DTD (Document Type Definition)¶

Not Supported - This older format is not available in FreeXmlToolkit.

Reason	Alternative
Less flexible than XSD	Convert your DTD to XSD
Limited features	Use XSD for the same rules
No namespace support	XSD handles namespaces

RelaxNG¶

Not Supported - This alternative schema format is not available.

Reason	Alternative
Less widely used	Use XSD instead
Focus on standards	Schematron for business rules

How to Use Schemas¶

Loading a Schema¶

Automatic: Open an XML file that references a schema (xsi:schemaLocation / xsi:noNamespaceSchemaLocation) - it is bound automatically
Manual: Open the Validation panel and click Change on the XSD row - or click the XSD indicator in the status bar and pick an .xsd file
Drag & Drop: Drop an .xsd file onto the Validation panel's XSD row or onto the status bar's XSD indicator

A Schematron rules file binds the same way via the Validation panel's Schematron row. Schematron files themselves (.sch) open as normal documents in the editor.

For JSON documents, a JSON Schema binds the same way: automatically via the document's $schema member, or manually via the status bar's JSON Schema indicator, the Validation panel's JSON Schema row, or drag & drop.

Validation Workflow¶

Open your XML file
Bind (or auto-detect) the schema
Click Run Validation in the Validation panel (or press F8) - or enable Validate while typing to check continuously
Problems appear in the PROBLEMS list, each tagged with its source (XSD, Schematron, Well-formed); click one to jump to the problem location
Fix issues and re-validate

Using Both XSD and Schematron¶

For the best validation coverage: - Use XSD for structure (elements, order, types) - Use Schematron for business rules (relationships, conditions)

Tips¶

Tip	Description
Start with XSD	XSD handles most validation needs
Add Schematron later	For business rules XSD can't express
Use auto-detection	Let the app find your schema automatically
Check error messages	They tell you exactly what's wrong

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