[DIGESTER-173] No way to enable schema validation from DigesterLoader

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 3.2
• Fix Version/s: 3.3
• Assignee: Simone Tripodi
• Reporter: Nick Williams
• Created: 10/Sep/12 15:59
• Updated: 18/Mar/13 07:41
• Resolved: 18/Mar/13 07:41

Description

It's possible that I'm using DigesterLoader with the improper assumptions, but my belief is that it is meant to be a factor of sorts for creating Digesters. If this is the case, the DigesterLoader interface is incomplete (and, for that matter, even if it is not the case, the documentation surrounding the use of Digester and DigesterLoader is seriously lacking).

I originally used the following code to digest my XML files:

this.loader = DigesterLoader.newLoader(module);
this.loader.setNamespaceAware(true);
this.loader.setSchema(schema);
this.loader.setValidating(true);
this.loader.setErrorHandler(new DefaultThrowingErrorHandler());
this.loader.setUseContextClassLoader(false);
this.loader.setClassLoader(Digester.class.getClassLoader());

...

this.loader.newDigester().parse(myFile);

However, I was getting strange errors "Document is invalid: no grammar found" and "must match DOCTYPE root null". Since I wasn't using a DOCTYPE, I had no idea why this was happening. Much Googling of other sources (the documentation did not help me with this) finally made me realize that setValidating() was turning on DTD validating, regardless of the fact that I was actually using schemas.

I finally figured out my code needed to be this:

this.loader = DigesterLoader.newLoader(module);
this.loader.setNamespaceAware(true);
this.loader.setSchema(schema);
this.loader.setErrorHandler(new DefaultThrowingErrorHandler());
this.loader.setUseContextClassLoader(false);
this.loader.setClassLoader(Digester.class.getClassLoader());

...

Digester digester = this.loader.newDigester();
digester.setFeature("http://xml.org/sax/features/validation", true);
digester.setFeature("http://apache.org/xml/features/validation/schema", true);
digester.setFeature("http://apache.org/xml/features/validation/schema-full-checking", true);

As you can see, I have to first get a Digester from the factory and THEN configure the digester further before I can use it. This is contrary to the standard factory pattern.

Proposal 1

• Deprecate setValidating(boolean) in DigesterLoader and Digester and replace them with setDoctypeValidating(boolean).
• Add a setSchemaValidating(boolean) method to DigesterLoader and Digester.
• Add a setFeature() method in DigesterLoader to mirror the one in Digester.

Proposal 2

• Document the setValidating(boolean) DigesterLoader and Digester methods better to indicate that it is for DOCTYPE validation and should not be used when using schemas.
• Add a setFeature() method in DigesterLoader to mirror the one in Digester.